Table of contents

The field and frequency dependences of the magnetic permeability in soft magnetic electroplated FeNiMo/Cu microwires were studied by means of their magneto impedance response. We analysed the influence of electroplating parameters such as current density, electrolyte composition and the presence of a magnetic field. It was found that the introduction of Mo as a third non-magnetic component causes large changes in the film permeability, which are associated with compositional and morphological effects. The electrodeposition under an external magnetic field induces a unidirectional anisotropy with the appearance of a large Barkhausen effect.

A magnetic field-assisted ball milling has been employed for the preparation of SmCo₅ + 10 wt% Fe nanocomposite powders in the presence of oleic acid as surfactant. Milling experiments were also carried out without using surfactant and the nanocomposite powders so obtained, with and without surfactant, were investigated for their structural and magnetic properties using SEM, XRD, VSM and Mössbauer spectrometry. The field-milled SmCo₅/Fe nanopowders in the presence of surfactant display a possible grain orientation and possess relatively high coercivity as compared with that of SmCo₅/Fe powders obtained with field-milling or conventional milling. Mössbauer studies revealed that the formation of α-Fe(Co) (soft magnetic phase) is more pronounced for the powders milled without surfactant.

The existing magnetic recording read head technologies use one of the well-known magneto-resistance effects (i.e. anisotropic magneto-resistance, giant magneto-resistance or tunnelling magneto-resistance (TMR)) to read back the data from the magnetic recording medium. These are usually sophisticated devices that require a dc test current flowing through the sensor stack in order to measure its change in resistance (i.e. amplitude response signal) as a function of the fringing magnetic flux of the recorded bits, when the reader moves along the recorded track. In this paper, we propose the design of a new kind of highly sensitive read sensor for magnetic recording heads, which directly produces a voltage response without the need for a test current. This new design is based on the magneto-electric effect in laminated multiferroic materials. Such a magnetic read head is much simplified in terms of sensor construction (i.e. number of layers involved and horizontal biasing requirements) and has a range of potential advantages including similar sensitivity to that of the TMR heads, reduced power consumption, better thermal performances, excellent high frequency operation and reduced cost of production.

We compare the performance of ruthenium-dye-sensitized, heterojunction solar cells formed from the p-type organic semiconductor poly (3-hexylthiophene), P3HT, and sintered nanocrystalline-titanium dioxide (nc-TiO₂) films prepared from different batches of sol–gel material. Atomic force microscopy shows that the RMS roughness of the nc-TiO₂ layers from these different batches ranged from 12.7 to 20.5 nm with the corresponding mean particle height ranging from 60 to 90 nm. Scanning electron microscopy reveals that these different topographies are linked to differences in the morphology of the sintered nc-TiO₂ layers.

Thermogravimetric analysis suggests that these structural differences may arise from differences in the solvent concentration in the nominally identical sol–gel solutions used for preparing the nc-TiO₂ layer. The best solar cell performance, achieved with films showing the highest RMS roughness and a 'columnar' morphology, displayed the highest external quantum efficiencies (EQEs) reported for this combination of materials: 11%<EQE<16% for the wavelength range 580–380 nm. However, the lower turn-on voltage for the dark, forward current in these devices leads to a reduction of ∼0.2 V in open-circuit voltage compared with the smoother films of nc-TiO₂.

Temperature-dependent photoluminescence (PL) properties of ZnO/Zn_0.9Mg_0.1O multi-quantum wells (MQWs) grown on Si (1 1 1) substrates by pulsed laser deposition have been investigated. For MQWs with well widths of 14 and 3 nm, the predominant excitonic emission in the whole temperature range (8–300 K) is attributed to bound excitons and localized excitons, respectively. The effect of quantum confinement on enhancing the intensity of the excitonic emission is clearly observed in the MQWs with well width of 3 nm, while the effect on blue-shifting the emission energy is not distinct, most probably due to the quantum confined Stark effect. The PL peak from the barrier layers shows an 'S'-shaped shift with increasing temperature due to localization of carriers in the potential minima induced by composition and interface fluctuations. The depth of the potential well is determined to be ∼15 meV.

The structure of porous Si samples prepared by conventional photoexcited electrochemical etching in hydrofluoric acid solution is presented. Strain enhanced cracking was evidenced at the surface of the sample, which was synthesized at higher incidence angle of light. Combined modes of carbon-fluorine and/or oxygen related impurities, and silicon-oxides are revealed from Fourier transform infrared investigation. A resonant feature at ∼467 nm, originating from a strong coupling of localized excitons at the Si/SiO₂ interfacial states and Si–O vibrational modes, is examined during photoluminescence measurements for an excitation wavelength of 320 nm. Furthermore, the appearance of luminescence bands in the range 378–412 nm is discussed in the light of a quantum confinement assisted radiative recombination of electrons and holes at impurity related defects or at the vacancies of neutral oxygen.

Surface morphology of green InGaN/GaN multi-quantum wells (MQWs) on a sapphire substrate with various high temperature grown GaN barriers has been evaluated. Keeping the InGaN well growth temperature constant at 740 °C, a series of MQWs were grown with GaN barrier temperatures varied up to 910 °C. GaN barriers grown below 800 °C lead to the generation of a high density of V-defects and inclusions embedded within V-defects as observed by atomic force microscopy. Scanning electron microscopy and cathodoluminescence (CL) studies revealed that the embedded inclusions are of two kinds: one of them appears as bright spots in CL mapping while the other appears as the surrounding region. Temperature ramping and subsequent interruption for GaN barrier growth suppresses both kinds of inclusion defects and also significantly reduces the V-defect density. An inclusion-free smooth surface is obtained for green emitting InGaN/GaN MQWs with the GaN barrier grown at 910 °C.

The luminescence properties of Tb³⁺-doped fluoride crystals under excitation with ionizing irradiation have been studied in order to assess the feasibility of using them as crystal detectors for in vivo radiotherapy dosimetry. In particular, it has been found that the radioluminescence intensity from both CsY₂F₇ and CsGd₂F₇ doped with 15 at% Tb³⁺ is almost six times that from the commercial Al₂O₃ : C detector. The spectral composition of emitted light has been analysed in order to determine the function of the Tb³⁺ activator ion during ionizing radiation-induced luminescence. The thermally stimulated luminescence of the crystals has also been investigated.

Phase change nonvolatile memory devices composed of SeSbTe chalcogenide semiconductor thin film were fabricated. The resistivity of the SeSbTe system was investigated to apply to multi-level data storage. The chalcogenide semiconductor acts as a programmable resistor that has a large dynamic range. The resistance of the chalcogenide semiconductor can be set to intermediate resistances between the amorphous and crystalline states using electric pulses of a specified power, and it can be controlled by repetition of the electric pulses. The size of the memory cell used in this work is 200 nm thick with a contact area of 1 µm diameter. The resistance of the chalcogenide semiconductor gradually varies from 41 kΩ to 840 Ω within octal steps. The resistance of the chalcogenide semiconductor decreases with increasing number of applied pulses. The step-down characteristic of the resistance can be explained as the crystalline region of the active phase change region increases with increasing number of applied pulses. The extent of crystallization was also estimated by the overall resistivity of the active region of the memory cell.

We have further improved our procedure for the optimization of multilayer semiconductor nanostructures, based upon diluted magnetic semiconductors, developed previously with the goal of maximizing their spin-filtering properties. The new optimization scheme relies on the application of a modern class of evolutionary algorithms for global optimization, specifically the genetic algorithm. Its fitness function is set to select the best possible spin-polarization properties within the chosen range of bias voltages and with a fixed value of external magnetic field. Numerical calculations are presented for the ZnSe/Zn_1−xMn_xSe based semiconductor system, and the obtained results predict an enhanced spin-diode performance over the existing designs.

We report the liquid phase epitaxial growth of Zn₃As₂ on InAs (1 1 0) substrates using 100% In solvent. The zinc concentration in the layers was varied by changing the zinc mole fraction in the growth melt from 3 × 10⁻³ to 15 × 10⁻³, keeping all other growth parameters constant. Layers grown with 3 × 10⁻³, 5 × 10⁻³ and 8 × 10⁻³ mole fractions of zinc seem to be polycrystalline, while layers grown with more than 8 × 10⁻³ mole fraction of zinc resulted in highly oriented and single crystalline material. Composition of the epilayers was confirmed by energy dispersive x-ray microanalysis. Scanning electron microscopy was used to determine the thickness of the epilayers and the growth rate was calculated. Furthermore it was found that a linear dependence exists between the growth rate and the zinc mole fraction in the growth melt. Atomic force microscopy results reveal that the smoothness of the epilayers improve when the zinc concentration in the epilayer approaches the stoichiometric value of Zn₃ As₂. Room temperature Hall measurements showed that the grown epilayers were unintentionally doped p-type with an increase in the carrier mobility and a decrease in the carrier concentration with respect to the increase in the zinc mole fraction in the growth melt.

Oxide heterojunctions composed of manganite films of different tolerance factors and SrTiO₃ : Nb are fabricated and their rectifying properties are experimentally studied. The current–voltage characteristics of the junctions are found to be dominated by diffusion current at high temperatures and by tunnelling current at low temperatures. Further analyses on the rectifying behaviours of the junctions indicate the occurrence of a built-in voltage independent of manganites, despite the great resistivity change of the manganites and the metal-to-insulator transition above 350 K (for La_0.67Sr_0.33MnO₃) and ∼87 K (for La_0.29Pr_0.38Ca_0.33MnO₃). In contrast, the increase in the Nb content causes a reduction of the built-in voltage by ∼0.2 eV. The presence of the depletion layer insensitive to the phase transition of the manganites is believed to be responsible for the present observations.

Vertically aligned ZnO films were deposited on n-InP by metalorganic chemical vapour deposition. X-ray diffraction, field emission scanning electron microscopy and photoluminescence measurements demonstrated that the ZnO films had good quality. By evaporating AuZn electrodes on both ZnO and InP surfaces, a ZnO-based light emitting device was fabricated. Under forward voltage, weak green emissions can be observed in darkness.

Spectra of perturbations of steady-state current transfer to cathodes of high-pressure argon arcs are computed in the framework of the model of nonlinear surface heating. The following pattern of stability has been established for a current-controlled arc on a cylindrical cathode on the basis of the numerical results and trends derived previously by means of an approximate analytical treatment: the diffuse mode is stable beyond the first bifurcation point and unstable at lower currents; steady-state modes with more than one spot are unstable; the axially symmetric mode with a spot at the centre of the front surface of the cathode is unstable; the 3D steady-state mode with a spot at the edge is unstable between the bifurcation point and the turning point and stable beyond the turning point; the transition between the latter mode and the diffuse mode is non-stationary and accompanied by hysteresis. Theoretical results are in agreement with trends observed in the experiment.

A confocal Fabry–Perot interferometer was utilized to study Ar–Ti, Ar–Cu and Ar–Cr dc magnetron discharges during sputtering of the corresponding metallic targets. Doppler broadening of Ar and Ti emission lines was measured in the wide range of Ar pressures and at different powers applied to the discharge. Spatial characterization of Ar and Ti line broadening through the discharge volume was also performed. Corresponding temperatures of Ar and thermalized Ti atoms were determined by Doppler broadening of the corresponding emission lines. Results show that the Ar temperature depends mainly on the working pressure in the reactor and it was found to be on average in the range 700–1300 K for the working pressure range 2–240 mTorr. The temperature of Ti was found to be about 600–800 K; it slightly increases with increasing applied power and does not depend on the working pressure in the reactor. Ar temperature measurements were verified by adding nitrogen in the discharge and by the measuring of the N₂(C, v' = 0 − B, v'' = 2) vibrational band shape.

An experimental investigation has been conducted to study the net flow direction induced by electrohydrodynamic forces in a wire-non-parallel plate electrode corona discharge. The experiments were conducted at two different locations of corona wire electrode for negative and positive applied voltage from 0 to 14 kV at atmospheric pressure and room temperature, where air was used as the working fluid. It was experimentally revealed that the net flow direction of electrohydrodynamically induced gas flow in a wire-non-parallel plate electrode system was changed depending on the location of the corona wire electrode relative to the grounded electrode position.

Spatially resolved optical emission spectroscopy and Langmuir probe measurement are used to investigate the characteristics of a cylindrical inductively coupled plasma in both E and H modes for Ar/N₂ discharges. Axial profiles of optical emission intensities are obtained and the results indicate that the electron density becomes non-uniform in the discharge region when the operating mode is changed from the E to the H mode. In the downstream region, electron density in the H mode is lower than that in the E mode, signifying a more lossy nature for the charged species in the E mode than in the H mode. The emission intensities of three argon lines show different behaviours during E to H transition in the downstream region. It is believed that they are due to the difference in contribution to the emission intensity by the metastables in the downstream region in these two modes.

The evolution of a high-density helicon discharge in argon and argon–helium mixtures was studied by spectroscopic methods as well as standard diagnostics. Applying optical emission spectroscopy, the electron temperature was deduced from the ratio of different emission lines. The spectral data were evaluated using collisional-radiative (CR) models taking account of secondary processes like the transitions between excited levels and excitation from metastable niveaus. In addition, time-resolved laser absorption spectroscopy was applied to determine the temperature and the density of the Ar*(³P₀) metastable atoms from the absorption profile of the 772.42 nm argon line. Due to strong coupling by electron collisions, the temperature of the metastable atoms up to 1000 K reflects the gas temperature of the ground state atoms. The gas temperature and the gas density, which is readily obtained from the temperature, are needed as input parameters for the CR models. The spectroscopic results were compared with Langmuir probe measurements which partially utilized passive compensation. The main issue of this study is electron heating due to helicon wave absorption. Applying a double radio-frequency (rf) pulse technique with variable rf power in the second pulse, the growth of the electron temperature was measured as a function of rf power. To clarify whether or not fast electrons are generated in the helicon wave due to resonant electron heating, phase-sensitive emission measurements of the Ar II (480 nm) line with a short lifetime (τ ≈ 7 ns) were performed on the rf time-scale (period 73.7 ns). However, no modulation of the Ar II emission synchronous with the helicon phase was observed. Rather, the temporal growth of the electron temperature reveals the electrons to be predominantly heated in the bulk of the energy distribution function.

There are numerous electromagnetic accelerator concepts which require plasma expansion through a magnetic nozzle. If the inlet flow is slower than one or all of the outgoing characteristics, namely, the Alfven, slow and fast magnetosonic speeds, then the number of inlet conditions which could be arbitrarily specified are reduced by the number of outgoing characteristics (up to three). We derive the axisymmetric compatibility equations using the method of projected characteristics for the inlet conditions in the z-plane to assure the boundary conditions being consistent with flow properties. We make simplifications to the equations assuming that the inlet Alfven speed is much faster than the sonic and slow magnetosonic speeds. We compare results for various inlet boundary conditions, including a modified Lax–Wendroff implementation of the compatibility equations, first order extrapolation and arbitrarily specifying the inlet conditions, in order to assess the stability and accuracy of various approaches.

Increasingly, NF₃-based plasmas are being used in semiconductor manufacturing to clean chemical vapour deposition (CVD) chambers. With advantages such as faster clean times, substantially lower emissions of gases having high global warming potentials, and reduced chamber damage, NF₃ plasmas are now favoured over fluorocarbon-based processes. Typically, a remote plasma source (RPS) is used to dissociate the NF₃ gas and produce atomic fluorine that etches the CVD residues from the chamber surfaces. However, it is important to efficiently transport F atoms from the plasma source into the process chamber. The current work is aimed at understanding and improving the key processes involved in the production and transport of atomic fluorine atoms. A zero-dimensional model of NF₃ dissociation and F production chemistry in the RPS is developed based on various known and derived plasma parameters. Additionally, a model describing the transport of atomic fluorine is proposed that includes both physical (diffusion, adsorption and desorption) and chemical processes (surface and three-body volume recombination). The kinetic model provides an understanding of the impact of chamber geometry, gas flow rates, pressure and temperature on fluorine recombination. The plasma-kinetic model is validated by comparing model predictions (percentage F atom density) with experimental results (etch rates).

The effects of the longitudinal pulse width were studied in Raman backward amplification (RBA) of laser pulses in plasmas. In RBA systems, which utilize Raman backscatter in plasmas, it is generally required that a long pump laser pulse, whose longitudinal pulse duration is typically tens of picoseconds, propagates more than a few millimetres of gas jet or capillary plasmas. However, from the experimental point of view, a short propagation distance of the pump pulse is more desirable to avoid various technical difficulties and physical instabilities. In this paper, the change in the characteristics of RBA systems for varying widths of the pump pulse is studied by fluid and kinetic simulations. The effects of the initial width of the seed pulse are also addressed.

Conduction currents and streamer initiation in cyclohexane with various additives have been investigated with fast impulses applied to a point-to-plane gap. The studied additives are perfluoro-n-hexane, N,N-dimethylaniline, 1-methylnaphthalene, di-n-propylether, 1,1-difluorocyclopentane and 1,4-benzoquinone, representing molecules with different electrochemical properties. We have used shadowgraphic imaging and a differential charge-measurement technique with a sensitivity of 0.1 pC to integrate currents induced to the point electrode, below and in the same voltage range where streamers first appeared. Effects on streamer initiation are found only for point anode streamers with the additive 1-methylnaphthalene, requiring higher voltages for initiation. We have observed transient conduction currents of measurable magnitudes in the nano to microampere range for voltages around initiation in all samples with a point anode and in 10 out of 21 samples with a point cathode. For a point anode, the more easily ionizable additives N,N-dimethylaniline and 1-methylnaphthalene induced somewhat larger currents. The results may be considered to support a hypothesis of electron avalanche induced streamer initiation, in that transient currents are induced by the ions left behind by the avalanches that are not sufficiently developed to initiate streamers.

We construct a collisional–radiative model for atomic H produced in H₂ gas at units and tens of mTorr pressures by a monoenergetic electron beam at units of keV energies. Unlike similar work in regimes of higher pressure and lower electron energies, we calculate the electron energy dependence of the two strongest Balmer lines (H_α and H_β). A key result is that the intensity ratios do not uniquely specify the electron energy, and so we propose a new method for measurement of the spatial energy profile using the absolute and relative intensities in tandem. The model shows qualitative agreement with semi-empirical distributions of absolute and relative intensities versus electron energy for beams emerging from a biconical hollow cathode.

Microwave plasma sources distributed on a planar matrix configuration can produce uniform bi-dimensional plasmas free from magnetic field in the 100 Pa pressure range. In argon, such uniform sheets of plasma have been obtained with ion densities in the range of 10¹² to 10¹³ cm⁻³ with microwave power ranging from 0.4 to 2 kW. The electrical characterization of the plasma has been investigated using a cylindrical Langmuir probe. A first feature concerns the plasma potential that exhibits quite high values due to the large increase in the electron temperature towards the source plane where the microwave electric field is applied. Secondly, the decrease in the electron temperature observed when increasing the microwave power can be justified by the apparition of multi-step ionization mechanisms via metastable and higher excited states of Ar atom. The concentration and temperature of Ar(³P₂) metastables have been measured by laser diode absorption spectroscopy. The results indicate that the presence of Ar(³P₂) metastables is significant at 2 cm from the source plane with concentration and temperature values varying from 10¹⁰ to 10¹¹ cm⁻³ and from 500 K to 1300 K, respectively, as functions of argon pressure and microwave power. An analytical model using a few simplifying assumptions provides a plasma picture in good agreement with the experimental results.

Plasma assisted catalytic technology, which uses synergetic technologies between the catalyst and plasma, has attracted much attention over the past several years. Theoretically, permittivity of a dielectric barrier influences the transferred charge of a microdischarge; thus high permittivity can improve the plasma reaction in a dielectric barrier discharge (DBD) plasma reactor. Despite the increased interest in the chemical processes, very little has been reported concerning the influence of materials of a dielectric barrier on DBD plasma reactions, since a high permittivity barrier generally exhibits low fracture strength and low dielectric strength making it break down under strong current pulses. In the present study, Ca_1−xSr_xTiO₃ (0.1 ≤ x ≤ 0.4) which possesses a high permittivity and a high fracture strength was prepared by liquid phase sintering and was used as a dielectric barrier for the destruction of carbon dioxide by a DBD plasma reaction. The permittivity of Ca_1−xSr_xTiO₃ (0.1 ≤ x ≤ 0.4) increased with increasing SrTiO₃ content; however, the observed CO₂ conversion became greatest using Ca_0.8Sr_0.2TiO₃ and then decreased with increasing SrTiO₃ content. These results imply that the reactivity of CO₂ destruction does not monotonously increase with increased permittivity of the Ca_1−xSr_xTiO₃ barriers. Both amplitude and density of the current pulses ignited by Ca_0.8Sr_0.2TiO₃ were much greater than that of Ca_0.6Sr_0.4TiO₃. Further, it was confirmed that a plasma reaction uniformly proceeded using the Ca_0.8Sr_0.2TiO₃ barrier, but proceeded non-uniformly using the Ca_0.6Sr_0.4TiO₃ barrier by observing the carbon deposition profiles on the surfaces of the barriers.

It was previously shown that plasma transport is enhanced by neutral gas depletion when the plasma pressure is not negligible compared with the neutral gas pressure. Consequently, the plasma flux leaving the discharge is not a linear function of the central plasma density. The latest theoretical treatments of this problem have assumed isothermal fluids in pressure balance, discarding neutral gas heating. We present a model that incorporates the effects of neutral gas heating on the plasma transport enhancement. This model shows that (i) neutral gas depletion is more pronounced than previously calculated due to gas heating and (ii) as a consequence the plasma transport is further enhanced and the non-linearity of the plasma flux leaving the discharge is more pronounced.

A high voltage (HV) pulse generator based on Blumlein technology was used to implant nitrogen ions into silicon substrates by immersion in a plasma generated by the HV pulse itself. Working pressures, applied HVs and treatment times were varied. Elemental depth profiles determined by Auger electron spectroscopy showed deeper penetration for higher voltages and broader profiles for increased treatment times indicating higher diffusion, as expected. Penetration depths, however, were about half of the values calculated by the SRIM code, probably due to the short duration of the HV pulse. The high-resolution x-ray diffraction ω/2θ scans measured around the (0 0 4) Si Bragg reflection of implanted samples had shoulders in the lower ω side, indicating a lattice expansion in the direction normal to the surface. Dynamical diffraction theory of Takagi–Taupin was used to fit the measured spectra, thus finding the strain profiles in the implanted samples. Both maximum strain values and integrated strains increased for samples implanted with higher voltages and treatment times and were almost independent of pressure.

The simple collisional–radiative model is investigated in low-pressure discharges containing argon and oxygen. Using this model, one can obtain a simple relationship between the electron density and the intensity ratio of two argon emission lines without knowing electron temperature. It is found that the relationship is valid in these discharges regardless of oxygen concentration, if argon np levels with zero total angle momentum quantum numbers are selected. This is because that the kinetics of these levels is not significantly affected by the metastables under low-pressure conditions. The application and validity of this model in other kinds of low-pressure plasmas, such as discharges contain CF₄, are also discussed.

The magnetization, resistivity ρ, thermoelectric power S, thermal conductivity κ and specific heat C_p in the layered cobalt oxide Nd_1−xSr_1+xCoO₄ (x = 0.25 and 0.33) have been investigated systematically. Based on the temperature dependence of susceptibility χ_m(T) and Seebeck coefficient S(T), a combination of the low-spin state for Co⁴⁺ and the intermediate-spin (IS) state for Co³⁺ can be suggested. The very large magnitude of S is suggested to originate from the configurational entropy of charge carriers enhanced by their spin and orbital degeneracy between Co³⁺ and Co⁴⁺ sites. In addition, based on the analysis of the temperature dependence of S(T) and ρ(T), the high temperature small polaron conduction and the low temperature variable range hopping conduction are suggested, respectively. As to thermal conduction κ(T), the decrease in κ with increasing Sr-doping is suggested to come from the combined effect of the scattering of the Co³⁺O₆ Jahn–Teller distortion with the IS state and the disorder to the phonon. Meanwhile, in the specific heat C_p(T) curves, the samples containing magnetic rare-earth Nd³⁺ ions reveal an obvious Schottky-type anomaly due to the crystal-field effects.

Titanium silicide (TiSi₂) is well known for application as a local interconnect material in complementary metal-oxide semiconductor technology. This paper reports on a comprehensive analysis of titanium silicide thin films by a variety of spectroscopy, diffraction and microscopy techniques. The composition and uniformity of the thin films and the oxygen contamination in the thin films is studied using Auger electron spectroscopy and secondary ion mass spectrometry; these have highlighted the existence of a thin film of uniform and desired composition, with a layer of oxide on the surface. Atomic force microscopy is used to study the surface morphology of the thin films. Microanalysis of the titanium silicide thin films was carried out using cross-sectional transmission electron microscopy; and a silicide–silicon interface which is abrupt and free of amorphous oxide is evident. X-ray diffraction (Bragg-Brentano and glancing angle), reflection high-energy electron diffraction and selected-area electron diffraction have been used to analyse the orientation of the thin films, and verify the presence of the desired C54 phase. The stress of the thin films is qualitatively studied by forming micro-beams of titanium silicide by bulk-micromachining of silicon, and the curvature of the micro-beams formed confirms tensile stress at the silicide–silicon interface. The thin films are also characterized using ellipsometry and thin film resistivity measurements.

ZnO, SnO₂ and zinc stannate thin films were deposited on commercial microscope glass and UV fused silica substrates using filtered vacuum arc deposition system. During the deposition, the substrate temperature was at room temperature (RT) or at 400 °C. The film structure and composition were determined using x-ray diffraction and x-ray photoelectron spectroscopy, respectively. The transmission of the films in the VIS was 85% to 90%. The thermal stability of the film electrical resistance was determined in air as a function of the temperature in the range 28 °C (RT) to 200 °C. The resistance of ZnO increased from ∼ 5000 to 10⁵ Ω when heated to 200 °C, that of SnO₂ films increased from 500 to 3900 Ω, whereas that of zinc stannate thin films increased only from 370 to 470 Ω. During sample cooling to RT, the resistance of ZnO and SnO₂ thin films continued to rise considerably; however, the increase in the zinc stannate thin film resistance was significantly lower. After cooling to RT, ZnO and SnO₂ thin films became practically insulators, while the resistance of zinc stannate was 680 Ω. The chemical stability of the films was determined by immersing in acidic and basic solutions up to 27 h. The SnO₂ thin films were more stable in the HCl solution than the ZnO and the zinc stannate thin films; however, SnO₂ and zinc stannate thin films that were immersed in the NaOH solution did not dissolve after 27 h.

Electrical activation of arsenic implanted in silicon on insulator (SOI) was studied. Two SOI structures with different Si overlayers and buried oxide thicknesses were used in this work. The As⁺ implantations were performed with a single energy of 20 keV to doses of 5 × 10¹⁴ cm⁻² or 2 × 10¹⁵ cm⁻² in both substrates. A plateau-like profile was achieved in an additional set of SOI samples by triple energy implantation. Rapid thermal and conventional furnace annealing were applied for dopant activation. Rutherford backscattering and Hall effect electrical measurements were done as well. The results are discussed, concerning electrical activation of As, considering the amorphization depth reached by dopant implantation and the crystal recovery process via thermal treatment. The completely amorphized samples presented higher values of sheet resistance and lower electrical activation percentage compared with the samples that did not have the complete top Si film amorphized. These results clearly show the need for avoiding total amorphization of the Si film during ion implantation in SOI, so that it is possible to achieve good crystal and electrical characteristics after thermal processing.

TiO₂ thin films were deposited by dc magnetron sputtering from sub-stoichiometric TiO_2−x targets. The as deposited films were XRD amorphous and their microstructure was varied by changing the Ar-pressure and the applied dc power during sputtering. An anneal treatment at 673 K/1 h in air resulted in the crystallization of a preferentially oriented anatase phase, the degree of which depended on the deposition conditions. The microstructure, optical and photocatalytic properties of the thin films were investigated using SEM, UV–VIS spectroscopy and a custom made photocatalytic test reactor, respectively. The thin film density was estimated from their refractive index. Density and crystallinity were the most important factors determining the photocatalytic activity of the thin films.

Structural evolutions of tungsten oxide(WO₃) samples on different substrates are studied using Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction and x-ray photoelectron spectroscopy. The WO₃ samples are prepared using hot-filament CVD techniques. The focus of the study is on the evolutions of nano structures at different stages following deposition time. The experimental measurements reveal evolutions of the surface structures from uniform film to fractal-like structures, and eventually to nano particles, and crystalline structures from mono (0 1 0) crystalline thin film to polycrystalline thick film developments. The effect of high temperature on the nanostructured WO₃ is also investigated. Well-aligned nanoscale WO₃ rod arrays are obtained at a substrate temperature of up to 1400 °C. Further increasing the substrate temperature yields microscale crystalline WO₃ particles.

Titanium dioxide (TiO₂) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (λ = 266 nm, τ_FWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO₂ thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters.

The strain evolution of a GaN layer grown on a high-temperature AlN interlayer with varying AlN thickness by metalorganic chemical vapour deposition is investigated. In the growth process, the growth strain changes from compression to tension in the top GaN layer, and the thickness at which the compressive-to-tensile strain transition takes place is strongly influenced by the thickness of the AlN interlayer. It is confirmed from the x-ray diffraction results that the AlN interlayer has a remarkable effect on introducing relative compressive strain to the top GaN layer. The strain transition process during the growth of the top GaN layer can be explained by the threading dislocation inclination in the top GaN layer. Adjusting the AlN interlayer thickness could change the density of the threading dislocations in the top GaN layer and then change the stress evolution during the top GaN layer's growth.

Thin films of hafnium oxide (HfO₂) have been grown by high pressure reactive sputtering on transparent quartz substrates (UV-grade silica) and silicon wafers. Deposition conditions were adjusted to obtain polycrystalline as well as amorphous films. Optical properties of the films deposited on the silica substrates were investigated by transmittance and reflectance spectroscopy in the ultraviolet, visible and near infrared range. A numerical analysis method that takes into account the different surface roughness of the polycrystalline and amorphous films was applied to calculate the optical constants (refractive index and absorption coefficient). Amorphous films were found to have a higher refractive index and a lower transparency than polycrystalline films. This is attributed to a higher density of the amorphous samples, which was confirmed by atomic density measurements performed by heavy-ion elastic recoil detection analysis. The absorption coefficient gave an excellent fit to the Tauc law (indirect gap), which allowed a band gap value of 5.54 eV to be obtained. The structure of the films (amorphous or polycrystalline) was found to have no significant influence on the nature of the band gap. The Tauc plots also give information about the structure of the films, because the slope of the plot (the Tauc parameter) is related to the degree of order in the bond network. The amorphous samples had a larger value of the Tauc parameter, i.e. more order than the polycrystalline samples. This is indicative of a uniform bond network with percolation of the bond chains, in contrast to the randomly oriented polycrystalline grains separated by grain boundaries.

Three series of silica thin films with thicknesses in the 300 nm range were deposited by spin coating on Si substrates using different compositions of the sol precursors. Film samples were thermally treated in static air at temperatures ranging from 300 to 900 °C. The effect of sol precursors and thermal treatment temperature on the film porosity was analysed by Fourier transform infrared (FTIR) spectroscopy, depth profiling with positron annihilation spectroscopy (DP-PAS) and the analysis of the capacitance–voltage (C–V) characteristic. The maximum of the total porosity was found to occur at a temperature of 600 °C when removal of porogen and OH groups was completed. Film densification due to the collapsing of the pores was observed after drying at 900 °C. DP-PAS provides evidence that the increase in the total porosity is related to a progressive increase in the pore size. The increase in the pore size never gives rise to the onset of connected porosity. In the silica film samples prepared using a low acidity sol precursor, the pore size is always lower than 1 nm. By increasing the acid catalyst ratio in the sol, larger pores are formed. Pores with size larger than 2.3 nm can be obtained by adding porogen to the sol.

In each series of silica film samples the shift of the antisymmetric Si–O–Si transversal optical (TO₃) mode upon thermal treatment correlates with a change of the pore size as evidenced by DP-PAS analysis. The pore microstructure of the three series of silica films is different at all the examined treatment temperatures and depends on the composition of the precursor sol.

Nanocrystalline ZnS films have been grown on glass substrates by close spaced evaporation at various deposition rates, with a constant substrate temperature of 300 °C. The x-ray photoelectron spectroscopy studies revealed that nearly stoichiometric ZnS layers were grown at deposition rates in the range 20–30 Å s⁻¹. The x-ray diffraction data confirmed the cubic structure of ZnS films for all the deposition rates. The surface morphological studies were made using an atomic force microscope, which indicated a rough surface and that the roughness increases with the deposition rate. The optical analysis showed that the layers grown at a deposition rate of 30 Å s⁻¹ exhibited the highest optical transmittance of 82%. The optical band gap of the films varied in the range 3.63–3.54 eV with the change in the deposition rate. The effect of the rate of deposition on the photoluminescence characteristics was also studied, which showed an increase in luminescence intensity with the decrease in the particle size. The electrical properties of the layers were highly influenced by the deposition rate. The temperature dependence of electrical conductivity was measured and the activation energies were also evaluated.

In this work we present the results of selective chemical etching of amorphous vanadium pentoxide films after their modification by ultraviolet (UV) radiation. V₂O₅ resist can be either positive or negative, depending on the developer composition. It was shown that UV-exposed V₂O₅ films after development and vacuum annealing can be transformed into VO₂ structures which exhibit an electrically induced resistance switching effect. The proposed method demonstrates the feasibility of using V₂O₅ as an effective inorganic resist material for ambient condition UV photomicrolithography. Also, this material has a great potential for fabrication of vanadium oxide-based devices.

Quasialigned ZnO/hexagonal ZnMgO/cubic ZnMgO nanopagoda heterostructures have been synthesized by a simple thermal evaporation method using Zn and Mg metals as raw materials. The structural, compositional and optical properties were investigated by field emission scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction, high-resolution transmission electron microscopy and room-temperature photoluminescence. The cubic ZnMgO structure was grown on the hexagonal ZnMgO interlayer and the ZnO nucleating layer. The nanopagodas are about 600 nm at the bottom and 70 nm at the top in diameter. The molar ratio of Zn-to-Mg decreases in the nanopagodas along the direction of the tip, while the average is 0.41 : 0.59. With Mg incorporation in the hexagonal ZnMgO interlayer, the ultraviolet near-band-edge emission shows a clear blueshift of 260 meV.

This work reports on the effect of diamond burs with coarse, medium and fine grit sizes and nickel or chromium coatings on in vitro dental resurfacing of a restorative porcelain. Process parameters such as tangential and normal forces, surface roughness, surface damage and morphology were studied as a function of removal rate using the different burs. At the lower removal rate, the differences for both the tangential and the normal forces were not significant among the coarse, medium and fine burs. However, when the porcelain was removed at the higher removal rate, both the tangential and the normal forces were markedly higher using the fine bur than those using the medium and coarse burs. Surface roughness values in terms of arithmetic mean and maximum roughness decreased significantly with a decrease in diamond grit size. The scale of surface damage in the form of brittle fracture decreased, and more transitions from brittle removal to ductile flow were observed when using finer grit diamond burs. In a comparison of the diamond bur topographies before and after dental finishing, it was found that minimal wear occurred on the nickel-coated coarse diamond bur, while minor abrasive wear occurred on the nickel-coated medium and chromium-coated fine burs.

Synchrotron radiation and a CCD detector were employed to map the full width at half maximum (FWHM) of rocking curves for a synthetic (0 0 1) oriented type Ib diamond plate. The plate was sawed from a diamond grown in the high-pressure–high-temperature (HPHT) process. Maps for broadening relative to a reference point on the diamond for the (2 2 4) reflection at 12 keV are reported before and after chemical etching. Significant rocking curve narrowing over most of the diamond was found, and we conclude that the diffraction performance of (0 0 1) oriented type Ib diamonds can be significantly improved over a large area by chemical etching. Stripes in the map before etching corresponded to grooves formed in the process of sawing the plate out of the as-grown stone. The FWHM map did not correlate with the surface height profile measured after ∼10 µm were removed from the surface by etching.

Compositional and temperature dependent thermoelectric power measurements have been performed on the polycrystalline manganite perovskite system: La_1−xCa_xMnO_3+δ (x = 0.00, 0.25, 0.33, 0.50 and 1.00), in the paramagnetic state (T > T_c) (300–673 K). The Seebeck coefficient (α) has been used to calculate the Fermi energy, the activation energy (E_α), the Mn⁴⁺-ion concentration and the oxygen content (δ), for different compositions. The observed decrease in E_α with increase in Ca-concentration and a large value of E_α as compared with a relatively high temperature sintered material of the same compositions have been explained in the light of the decrease in the interatomic distances and grain growth with Ca-substitution. It is shown that [Mn⁴⁺][Mn³⁺] ion concentration is not the only factor that governs conduction in the manganite perovskites. The significantly small values of α (−22 µV K⁻¹) at high temperature can be explained on the basis of (Mn³⁺–Mn³⁺) charge disproportionation into stable Mn²⁺–Mn⁴⁺pairs in the system rather than on the basis of nominal Mn^3+/4+ valence arguments. Finally, nearly temperature independent variation of α, charge-carrier concentration at high temperature and low value of mobility are hallmarks of small polaron hopping.

Polycrystalline ingots of Pb_xSn_1−xTe_0.5Se_0.5 (x = 0.4, 0.6, 0.8 and 1.0) were synthesized. Thin films of Pb_xSn_1−xTe_0.5Se_0.5 were prepared by conventional thermal evaporation of the prereacted materials. The chemical composition of the starting materials as well as thin films revealed that they are nearly stoichiomeric. The crystal structure and the unit cell lattice parameters of the starting materials were determined from x-ray diffraction studies. It was revealed that the as-deposited and annealed films are polycrystalline with the single phase of the rock salt (NaCl) structure as that of the bulk material with a (2 0 0) predominant reflecting plane. The optical absorption of the annealed films at 473 K was determined from the optical transmittance data in the spectral range 2.5–10 µm. The analysis of the optical absorption spectra of the investigated films revealed direct energy gaps. However, the band gaps showed linear variation with the value of x.

The morphology and optical properties of Si samples implanted by low-energy Fe⁺ ions with different fluences (1 × 10¹⁵–1.8 × 10¹⁷ cm⁻²) and further subjected to pulsed ion-beam treatment (PIBT) have been studied by atomic force microscopy and optical reflectance spectroscopy. It was proved that iron disilicide (β-FeSi₂) crystallites were formed on the surface of the Si substrate as a result of ion implantation and PIBT. The method of ultrahigh vacuum and low-temperature (T = 850 °C) cleaning of Fe⁺-implanted Si samples has been applied for the first time. It was found that it is possible to form smooth epitaxial Si films with both a thickness of up to 1.7 µm and a reconstructed surface by molecular beam epitaxy on the surface of Si samples implanted with a fluence of up to 1 × 10¹⁶ cm⁻². Further increase in the implantation fluence results in the disruption of epitaxial Si growth and to a strong increase in surface relief roughness due to 3D silicon growth mechanism. Preservation of β-FeSi₂ precipitates inside the Si matrix after the formation of a cap epitaxial Si layer has been confirmed by optical spectroscopy data. Low temperature photoluminescence measurements in the range 1400–1700 nm showed that light emission of the formed Si/β-FeSi₂/Si heterostructures is due to contributions from β-FeSi₂ precipitates and dislocations.

Using a large pressure-jump apparatus and Bridgman anvils, the Grüneisen parameters of iron and copper were measured under high pressures of 4.58–7.49 GPa and 4.40–6.25 GPa, respectively. Substitution of ΔT/ΔP for ∂T/∂P at median pressure is strictly justified and the Grüneisen parameter at the median pressure was determined by a modified thermodynamic relationship γ (P_m) = [K_s(P_m)/T(P_m)](ΔT/ΔP), where P_m indicates the median pressure, and adiabatic correction of the temperature change was completed through analysing the experimental data. The new γ values obtained are reconcilable with previous reports, and their tendency with pressure is also in good agreement with the previous work. The results suggest that the improved method is reliable for measurements of the Grüneisen parameter at high pressure, and is promising for such measurements to the higher pressure range.

The aim of this study is to investigate the electromagnetic properties of nanoparticle colloids in the frequency range 1 MHz–20 GHz, with focus on the electromagnetic absorption mechanisms at microwave frequencies. A broad range of magnetic and dielectric properties are investigated and a number of mechanisms are highlighted for tailoring the electromagnetic performance. Results from the Co_xNi_1−x series, with particle sizes ranging from 25 to 200 nm, show particle size-related dielectric and magnetic properties, which aid the optimization of the resulting properties, in addition to conventional mechanisms, which are also demonstrated in colloidal form. A further reduction in particle size to below 20 nm leads to single magnetic domain particles, which also exhibit enhanced electromagnetic properties, as demonstrated with broadband magnetic performance achieved for Co ferrofluid with an average particle size of 5 nm.

In pursuit of reproducible, vacuum-compatible, long-lived cathodes for use in high power microwave devices, we have examined the microstructure changes of cathode surfaces after electron emission during high-voltage pulsed operation of explosive emission cathodes. Measurements of the surface damage for stainless steel and velvet cathodes demonstrated that the smoothing of the cathode surface microstructure obviously occurred on the surface of cathodes subjected to the electron emission. Carbon fibre cathodes after electron emission were found to show surface erosion on the top and side surfaces of carbon fibre. The experimental results from the carbon fibre cathodes suggest that explosive electron emission and surface flashover together occurred in the process of cathode electron emission. There was a decrease in the number of emitters on the cathode surfaces of stainless steel and velvet cathodes after electron emission. However, the number of emitters did not decrease but increased in the case of the carbon fibre cathode after emission. These results show that carbon fibre cathodes have an outstanding advantage over the other cathodes on the cathode lifetime.

Lead-free (Bi_0.5Na_0.5)_{1−x−y−x}Ba_x Sr_yCa_zTiO₃ piezoelectric ceramics have been prepared by a conventional mixed oxide method, and their structural and electrical properties have been studied. The results of x-ray diffraction reveal that Ba²⁺, Sr²⁺ and Ca²⁺ diffuse into the Bi_0.5Na_0.5TiO₃ lattices to form a solid solution with a single-phase perovskite structure, and a morphotropic phase boundary (MPB) exists at x = 0.04–0.08, y = 0.015, z = 0.01. After the substitutions of Ba²⁺, Sr²⁺ and Ca²⁺, the ceramics exhibit a lower coercive field E_c and a larger remanent polarization P_r, which facilitates the poling and leads to an improvement in the piezoelectric coefficient d₃₃ and the planar electromechanical coupling factor k_P. Also, the depolarization temperature T_d decreases, showing a strong dependence on the substitution level of Ba²⁺. For the ceramics with the compositions near the MPB, P_r = 44 µC cm⁻², d₃₃ = 173 pC N⁻¹, k_P = 34% and T_d = 120 °C. In addition, the ceramics exhibit a relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The results of the ferroelectric and dielectric properties at high temperatures suggest that the ceramics may contain both the polar and non-polar regions at temperatures above T_d.

We have analysed the effect of silver content on the optical properties of Ag-photodoped amorphous Ge_xSb_40−xS₆₀ (with x = 10, 20 and 30 at.%) chalcogenide thin films; the chalcogenide host layers were prepared by vacuum thermal evaporation. Films of composition Ag_y(Ge_xSb_40−xS₆₀)_100−y, with y ≲ 10 at.%, were prepared by successively photodissolving about 10 nm thick layers of silver. The film thickness and optical constants have been accurately determined by a refined envelope method, based upon the two envelope curves of the optical-transmission spectrum, obtained at normal incidence. The dispersion of the linear refractive index of the Ag-photodoped chalcogenide films is analysed in terms of the Wemple–DiDomenico single-effective-oscillator model. We have found that the maximum change in the index of refraction, between the Ag-photodoped and the undoped material, is about 0.08, when the Ag-concentration reaches the level of saturation of around 10 at.%. On the other hand, the Tauc gap, , decreases notably, with increasing Ag-content: for instance, in the particular case of x = 10 at.%, the smallest Ge-content, decreases from 1.97 down to 1.67 eV.

The shock response of a two-dimensional glass-fibre–epoxy composite has been investigated in terms of orientation of the fibres to the loading axis. Results show that when shocked in the through thickness orientation (fibres normal to the loading axis), the resultant shock pulses are similar to many other monolithic materials, and the shock velocity–particle velocity is linear. Examination of the spall response as a function of specimen thickness and the release velocities has also led us to suggest that the shock pulse generates damage behind it, which accumulates as a function of pulse duration. In contrast, when shocked along a fibre direction, the shock pulses have a strongly ramped nature, which steepens to a shock at higher stress amplitudes. Analysis of the wave velocity–particle velocity behaviour has led us to suggest that a low amplitude stress pulse is transmitted along the fibres, with the higher amplitude remainder being transmitted in the 'matrix'—i.e. the epoxy binder and fibres normal to the loading axis between them. Such a response has been observed in other fibre-based composites, and it is believed that this is due to the structural configuration of such materials.

Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its electrical properties. Besides experimental measurements, material theoretical models can be useful to investigate its behaviour with respect to frequency, moisture content or other factors. These models can be used in electromagnetic compatibility (EMC) to predict the shielding effectiveness of a concrete structure against external electromagnetic waves. This paper presents the development of a dispersive material model for concrete out of experimental measurement data to take account of the frequency dependence of concrete's electrical properties. The model is implemented into a numerical simulator and compared with the classical transmission-line approach in shielding effectiveness calculations of simple concrete walls of different moisture content. The comparative results show good agreement in all cases; a possible relation between shielding effectiveness and the electrical properties of concrete and the limits of the proposed model are discussed.

The asymmetric fatigue behaviour of electric-pulse-induced resistance switching, that is, only switching from a low to a high resistance state, exhibits obvious fatigue behaviour and has been investigated in Ag–La_0.7Ca_0.3MnO₃–Pt heterostructures. This asymmetric fatigue is strongly dependent on the applied electric-pulse voltage and can be refreshed by applying a voltage sweep in vacuum condition (<100 Pa). The fatigue and its refreshment are related to the increase and decrease in threshold voltage in the resistance switching, respectively. The results indicate that fatigue endurance in resistance switching of Ag–La_0.7 Ca_0.3MnO₃–Pt heterostructures can be improved through the operation of environmental oxygen pressure.

A self-similarity model applying the Sierpinski carpet approximation for the effective dielectric constant of nanoporous low-k dielectrics is proposed based on the statistically self-similar characteristics of pore size distributions in the medium and on the 'mixture rule' technique. The proposed model for the dielectric constant is expressed as a function of porosity (related to stage n of Sierpinski carpet) and the dielectric coefficient of components of the medium. The model predictions are compared with the existing experimental data and with other model predictions, and good agreement is obtained between the present model predictions and the experimental data. The proposed technique may have the potential of analysing other properties such as thermal conductivity and Young's modulus.

Carbon-coated Fe [Fe(C)] nanocapsules were synthesized by a modified arc-discharge method, and their microstructure and electromagnetic (EM) properties (2–18 GHz) were investigated by means of transmission electron microscopy, Raman spectroscopy and a network analyser. The reflection loss R of less than −20 dB was obtained in the frequency range 3.2–18 GHz. A minimum reflection loss of −43.5 dB was reached at 9.6 GHz with an absorber thickness of 3.1 mm. The in-depth study of relative complex permittivity and permeability reveals that the excellent microwave absorption properties are a consequence of a proper EM match in microstructure, a strong natural resonance, as well as multi-polarization mechanisms, etc.

Camera observations of the full penetration keyhole laser welding process show that the keyhole shape is elongated under certain welding conditions. Under these unfavourable circumstances, the welding process is susceptible to holes in the weld bead. Existing models of the pressure balance at the keyhole wall cannot explain this keyhole elongation. In this paper a new model is presented, accounting for the doubly curved shape of the keyhole wall. In this model, the surface tension pressure has one term that tends to close the keyhole and another term that tries to open it. Model calculations show that when the keyhole diameter is of the same order as the sheet thickness, the latter part can become dominant, causing the keyhole to elongate. Experiments on thin aluminium (AA5182) and mild steel (DC04) sheets verify these model calculations. As the keyhole radius depends on the radius of the focused laser spot, it was found for both materials that the ratio of the spot radius and the sheet thickness must be above a critical value to prevent keyhole elongation. These critical radii are 0.25 for AA5182 and 0.4 for DC04, respectively. Furthermore, differences in appearance of the weld bead between the circular and the elongated keyhole welds could be explained by this model.

Experimental evidence for the generation of intrinsic localized modes (ILMs) in a nonlinear electrical transmission line is presented both via modulational instability of the uniform mode and via driving the lattice locally. The spatial profiles of these modes localized on the order of the lattice spacing can be directly measured in this macroscopic lattice, in contrast to most other systems where ILMs have so far been detected.

In the second last paragraph of section 4 on page 716 of the paper, the descriptions (labelled (1) and (2)) that map ϕ provides for the two limiting behaviours for a viscoelastic solid are stated incorrectly and should be revised to:

(1) For the contact of an elastic solid (for which D is constant and τ → ∞) with another, ϕ(p, t) ≈ 1 − exp[−(pD)^c] for 0 ≤ t. because A(p,0) = A(p,∞), since an elastic solid deforms at the instant of loading (t = 0) but not after that. Thus, at a given p > 0, the contact area quickly settles to some constant value. The contact area for the pair increases monotonically with the applied load but never exceeds its upper bound A_∞.

(2) When a viscous liquid (for which D is large and τ → 0⁺) is pressed against a solid to some high enough p > 0, ϕ(p, t) ≈ 1 − exp[−(pD)^c] → 1^- for 0 < t. Thus, the contact area for the pair approaches its upper bound A_∞ at relatively short dwell times.