Table of contents

Recent research activities on the linear magnetoelectric (ME) effect—induction of magnetization by an electric field or of polarization by a magnetic field—are reviewed. Beginning with a brief summary of the history of the ME effect since its prediction in 1894, the paper focuses on the present revival of the effect. Two major sources for 'large' ME effects are identified. (i) In composite materials the ME effect is generated as a product property of a magnetostrictive and a piezoelectric compound. A linear ME polarization is induced by a weak ac magnetic field oscillating in the presence of a strong dc bias field. The ME effect is large if the ME coefficient coupling the magnetic and electric fields is large. Experiments on sintered granular composites and on laminated layers of the constituents as well as theories on the interaction between the constituents are described. In the vicinity of electromechanical resonances a ME voltage coefficient of up to 90 V cm⁻¹ Oe⁻¹ is achieved, which exceeds the ME response of single-phase compounds by 3–5 orders of magnitude. Microwave devices, sensors, transducers and heterogeneous read/write devices are among the suggested technical implementations of the composite ME effect. (ii) In multiferroics the internal magnetic and/or electric fields are enhanced by the presence of multiple long-range ordering. The ME effect is strong enough to trigger magnetic or electrical phase transitions. ME effects in multiferroics are thus 'large' if the corresponding contribution to the free energy is large. Clamped ME switching of electrical and magnetic domains, ferroelectric reorientation induced by applied magnetic fields and induction of ferromagnetic ordering in applied electric fields were observed. Mechanisms favouring multiferroicity are summarized, and multiferroics in reduced dimensions are discussed. In addition to composites and multiferroics, novel and exotic manifestations of ME behaviour are investigated. This includes (i) optical second harmonic generation as a tool to study magnetic, electrical and ME properties in one setup and with access to domain structures; (ii) ME effects in colossal magnetoresistive manganites, superconductors and phosphates of the LiMPO₄ type; (iii) the concept of the toroidal moment as manifestation of a ME dipole moment; (iv) pronounced ME effects in photonic crystals with a possibility of electromagnetic unidirectionality. The review concludes with a summary and an outlook to the future development of magnetoelectrics research.

The frequency and temperature dependences of the hysteresis loops in Pb[(Zr_0.52Ti_0.48)_0.95(Mn_1/3Nb_2/3)_0.05]O₃ ceramics have been investigated. The polarization-field hysteresis curves show 'pinched' shapes at room temperature and higher frequencies, whereas they display normal square-like loops at 200°C and frequencies lower than 10 mHz. Critical ferroelectric features such as the coercive field, polarization and internal bias field show a strong frequency or temperature dependence. The close relations between the P–E loops and the applied frequency and temperature indicate that the defect dipolar moment may change its magnitude with variation of the frequency or temperature. Comparing with the intrinsic depinning procedure induced by the changes in the distribution of defect dipoles, we provide new evidence for an extrinsic depinning mechanism of the defect dipoles in the bulk ceramics.

While most recent studies of the spin-transfer torque effect mainly deal with magnetic structures with in-plane anisotropies and magnetizations, we theoretically investigate the magnetization behaviour driven by spin-currents in a trilayer structure with perpendicular anisotropy and magnetization using a modified Landau–Lifshitz–Gilbert equation. This study is particularly conducted for hysteresis loop measurements under spin-currents and current–voltage measurements in the presence of external magnetic fields, by which the unique magnetization rotations and reversals associated with the spin-transfer torque in the magnetic configuration can be captured.

The properties of photonic defect modes in a chiral photonic structure were investigated using the finite element method. By stacking two cholesteric liquid crystal (ChLC) films, the defect mode due to the introduction of a twist defect was considered in both cases of chiral structures with constant pitch and spatially varying pitch. Two types of linear pitch gradients for achieving a broadband reflection were analysed, and the number of chiral pitches required for establishing the stop band was simulated. The effect of a finite sample thickness on the energy density distribution of the defect mode and on the required polarization of the incident light to excite the defect mode was studied. In both cases of constant pitch and spatially varying pitch, an unusual crossover behaviour in reflection at the defect resonance wavelength of a single circularly polarized mode appears when the structure thickness increases beyond a specific value. The energy distribution inside the sample also reveals the unusual distribution. Two different resonance wavelengths can be created by a twist defect in the ChLC composite film with linearly varying pitch, while only one resonance wavelength can be created in the identical film with constant pitch.

Crystalline boron nitride nanotubes (BNNTs) with an average outer diameter of about 40 nm and several micrometres in length were synthesized by chemical vapour deposition from boron and magnesium oxide. Rietveld refinement and ¹¹B solid-state nuclear magnetic resonance (NMR) spectroscopy were employed to quantitatively determine the phase of synthesized BNNTs. The structural parameters for the BNNTs were determined by Rietveld refinement against powder x-ray diffraction data with a model based on the results of NMR analysis. The final weighted R-factor, R_wp, was 6.08% and the goodness-of-fit indicator, S (= R_wp/R_e), was 1.52. The BNNTs consisted of hexagonal BN, rhombohedral BN and MgO with refined weight fractions of 76.3%, 21.2% and 2.5%, respectively.

The quasi-four-probe resistivity measurement on the microcrystal of 1,4-bis[(4-heptyloxyphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-3) is carried out under variable pressure and temperature conditions using a diamond anvil cell (DAC). Sample resistivity is calculated with a finite element analysis method. The temperature and pressure dependences of the resistivity of OXD-3 microcrystal are measured up to 150°C and 15 GPa, and the resistivity of OXD-3 decreases with increasing temperature, indicating that OXD-3 exhibits organic semiconductor transport property in the region of experimental pressure. With an increase of pressure, the resistivity of OXD-3 first increases and reaches a maximum at about 8 GPa, and then begins to decrease at high pressures. From the x-ray diffraction data in DAC under pressure, we can conclude that the anomaly of resistivity variation at 8 GPa results from the pressure-induced amorphism of OXD-3.

A bright white electroluminescence (EL) emission can be achieved using a minimum doping technique, that is, the concentration of the dopant DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljuloli-dyl-9-enyl)- 4H-pyran) was controlled to be 0.5 wt% of the host BAlq (bis(2-methyl-8-quinolinolato)(para-phenylphenolato)aluminium(III)). The white EL device structure is ITO/copper phthalocyanine (CuPc) (5 nm)/N, N'-bis(naphthyl)-N, N'-diphenyl-1,1'- biphenyl-4,4'-diamine(NPB)(50 nm)/BAlq : DCJTB(0.5 wt%, 30 nm)/tris(8-hydroxyquinolinato) aluminium(III)(Alq₃)(20 nm)/LiF(0.5 nm)/Al(100 nm). The white emission is composed of a red band from DCJTB and a blue emission from BAlq. A maximum luminance of 21 000 cd m⁻² at the direct current driving voltage of 15 V, with a power efficiency of 1.10 lm W⁻¹ at 11 V is achieved. The Commission Internationale de L'Eclairage coordinates of the white emission are well within the white zone which moves from (0.32, 0.34) to (0.30, 0.32) when the applied voltage is varied from 8 to 11 V.

Thin {111} GaAs substrates were deformed by a Vickers indenter at 350°C–370°C under loads ranging between 0.4 and 1.9 N. Optical microscopy and interferometry were used to observe the indented and opposite faces of the thin foils and hence to investigate the plastic flow through the samples. Attention was paid to the polarity (A or B) of the specimen surface, as GaAs is known to show a large difference between α and β dislocations mobilities. A model considering the influence of polarity is proposed to describe the material flow throughout thin samples.

Organic field-effect transistors using pentacene have been fabricated employing polyimide gate dielectric layers. The root-mean square surface roughness of polyimide films is 9 Å. Devices with thin polyimide films as gate achieved a mobility of 0.16 cm² V⁻¹ s⁻¹, threshold voltage −6.4 V, on–off ratio ∼ 10⁴ and subthreshold slope 7.5 dec⁻¹ with the gate voltage span between 0 and −30 V. The upper limit of interface trap density has been estimated to be 3.9 × 10¹² cm⁻² eV⁻¹. The mobility is found to be gate bias dependent.

Aligned TiO₂ nanowire arrays were fabricated onto Si wafers by a simple thermal deposition (PVD) method. Scanning electron microscopy and high-resolution transmission electron microscopy observations confirm that the as-prepared TiO₂ nanowires are single-crystalline and of high purity. Field emission measurements showed that the TiO₂ nanowire arrays could provide stable, high-current electron emission at a low voltage. The emission current monitored over a period of 24 h fluctuated gently but did not show degradation. The cathode-luminescence (CL) images captured by a CCD camera were very bright and their CL intensity was homogeneous. This remarkable performance reveals that TiO₂ nanowire arrays are well suited for commercial use in electron devices, particularly flat panel displays.

The electron energy distribution function (EEDF) was determined from the second derivative of the I–V Langmuir probe characteristics and, thereafter, theoretically calculated by solving the plasma kinetic equation, using the black wall (BW) approximation, in the positive column of a neon glow discharge. The pressure has been varied from 0.5 to 4 Torr and the current from 10 to 30 mA.

The measured electron temperature, density and electric field strength were used as input data for solving the kinetic equation.

Comparisons were made between the EEDFs obtained from experiment, the BW approach, the Maxwellian distribution and the Rutcher solution of the kinetic equation in the elastic energy range. The best conditions for the BW approach are found to be under the discharge conditions: current density j_d = 4.45 mA cm⁻² and normalized electric field strength E/p = 1.88 V cm⁻¹ Torr⁻¹.

An investigation of ion beam emission from a low energy plasma focus (PF) device operating with methane is reported. Graphite collectors, operating in the bias ion collector mode, are used to estimate the energy spectrum and ion flux along the PF axis, using the time-of-flight technique. The ion beam signals are time correlated with the emission of soft x-ray pulses from the pinched focus plasma. The correlation of ion beam intensity with filling gas pressure indicates that the beam emission is maximized at the optimum pressure for focus formation at peak current. Ion beam energy correlations for operation in methane indicate that the dominant charge states in carbon ions are C⁺⁴ and C⁺⁵. The estimated maximum ion energy for H⁺, C⁺⁴ and C⁺⁵ are in the range of 200–400 keV, 400–600 keV and 900–1100 keV, respectively, whereas their densities are maximum for the energy range 60–100 keV, 150–250 keV and 350–450 keV, respectively. These results suggest that the ion beams are emitted from a high density, high temperature, short lived focus plasma, at a time which appears to precede the emission of soft x-ray pulses. The properties of the carbon ion beams are discussed in the context of potential applications in materials science.

Results of spectral and photometric measurements are presented for pulsed power operated high intensity discharges (HIDs). This investigation is related to the application of a pulsed power supply for pile driving of HID lamps. Specifically, we are interested in controlling the spectral response radiation of visible and ultraviolet (UV) lines for tertiary treatment of water using UV radiation. Simulations based on a physical model of the lamps were conducted. These results relate to the radial temperature, line intensity and electrical properties (voltage, power and conductivity). Good agreement has been found between the results of the simulations and the experimental findings.

Electron paramagnetic resonance was conducted on aluminium oxide films deposited by atomic layer deposition on (100)Si. Multiplet spectra are observed, which can be consistently decomposed assuming the presence of only P_b0 and P_b1 centres, which are well known in Si/SiO₂ structures. Al₂O₃ films deposited on HF-treated (100)Si exhibit unpassivated P_b0 and P_b1 centres, with concentrations of (7.7 ± 1.0) × 10¹¹ cm⁻² and (8 ± 3) × 10¹⁰ cm⁻², respectively. Rapid thermal annealing of the substrate in NH₃ prior to film deposition reduces the unpassivated P_b0 concentration to (4.5 ± 0.7) × 10¹¹ cm⁻². Forming gas annealing at temperatures in the range 400–550°C causes no further reduction in defect density; this may be related to a spread in passivation activation energy, associated with low-temperature deposition.

In this study, the digital atomic force microscope (AFM) Moiré method with phase-shifting technology is established to measure the in-plane displacement and strain fields. The Moiré pattern is generated by the interference between the specimen grating and the virtual reference grating formed by digital image processes. The overlapped image is filtered by two-dimensional wavelet transformation to obtain the clear interference Moiré patterns. The four-step phase-shifting method is realized by translating the phase of the virtual reference grating from 0 to 2π. The principle of the digital AFM Moiré method and the phase-shifting technology are described in detail. Experimental results show that this method is convenient to use and efficient in realizing the microscale measurement.

Superconducting thin films of Nd_1−xY_xBa₂Cu₃O_7−δ (x = 0.053, 0.106 and 0.159) have been grown on single crystal SrTiO₃ substrates by pulsed laser deposition. The orientation of the films was investigated by x-ray diffraction. The surface morphology of the films was examined by atomic force microscopy and scanning tunnelling microscopy. Qualitative and quantitative elemental analyses of the films were carried out by using electron probe microanalysis. Micro-Raman spectroscopy was used to study the oxygen sublattice vibrations of the films. The effects of annealing were also investigated after patterning device structures in the films.

We have simulated the structural and vibrational properties of NdMn₈T₄ compounds (T = Fe, Co, Ni), using the inverted pair potentials Φ_Mn–Mn(r), Φ_Nd–Mn(r), Φ_Nd–R(r), Φ_Nd–T(r), Φ_Mn–T(r), and Φ_T–T(r). The calculated site preference of the third element, T, is found to be the 8f site. The difference in the lattice parameters between the calculated and the experimental values is less than 3.0%. These results are in agreement with experiments. Moreover, the total and partial phonon densities of states are first evaluated for the NdMn₈T₄ compounds. A qualitative analysis is carried out with the relevant potentials for the vibrational modes, which makes it possible to predict some properties related to lattice vibration.

The π-electron states of a graphite/porous-graphite quantum wire are calculated in the effective-mass theory. The wire-width dependence of sub-band levels is well reproduced for lower sub-bands of wider quantum wires. The effective-mass along a quantum wire is proportional to the sub-band level and exhibits a drastic change as a function of the wire width.

The adhesive contact between an elliptical rigid flat-ended punch and an elastic half space was analysed in this study. Non-self-similar growth in the contact area was obtained. The separation was found to initiate at the edges of the major axis, which would lead the elliptical contact to a circular contact. The pull-off force for the initiation of separation increases from the slim elliptical contact to the circular contact and is proportional to the square root of the interfacial energy and shear modulus of the elastic material. A relation between the pull-off force and the corresponding punch displacement was obtained, which is independent of the elastic properties of elastic materials.

Reflective, pinhole-free Fe/Fe₃O₄ and Fe_3−δO₄/Fe₂O₃ nanocomposite films were obtained by reacting iron pentacarbonyl, Fe(CO)₅, in an inductively-coupled radio frequency glow discharge reactor. The conductivity of the Fe_x/(Fe₃O₄)_1−x (x > 7%) composite films exhibits metallic characteristics and the conductivity decreases as the α-Fe content decreases. The metal-to-insulator transition temperature of the Fe_x/(Fe₃O₄)_1−x (x ∼0.07) films shifts to a higher temperature as compared with Fe_3−δO₄ due to the increased conductivity from α-Fe. The magnetization versus temperature (M–T) curves show the transition temperature ranging from 95 to 136 K, corresponding to the Verwey temperature, which is dependent on the film composition. The Fe_3−δO₄ film exhibits a negative magnetoresistance of about 4% and 8% at room temperature and 80 K, respectively.

The influence of the waveform on the surface charging of a spacer stressed by impulse voltages is investigated in this paper. The experimental study was carried out using a simplified spacer with an adhering conducting particle under homogeneous conditions in SF₆ gas. A capacitive probe was specially designed to yield the surface charge data through potential measurement. The results show that the impulse waveform has a significant influence on charge accumulation on the spacer surface. Also, the measurements of the optical signal occurring in the predischarge process can give an explanation for the mechanism of charge accumulation on the spacer surface in the presence of impulse.

A numerical simulation is used to investigate the effect of rod dimensions on lightning attachment to the lightning rod. The effect is studied by considering a sequence of discharge processes, from a corona ignited in a slowly rising thundercloud electric field to the development of an upward leader in the electric field of an approaching downward leader. It is concluded that the efficacy of a lightning rod is almost independent of the rod radius in the range 0.05–5 cm. This is in agreement with measurements of the breakdown voltage in long laboratory rod-to-plane air gaps for various rod tip radii but is at variance with the conclusions reached by Moore et al (2000a Geophys. Res. Lett.27 1487, 2000b J. Appl. Meteorol.39 593, 2003 J. Appl. Meteorol.42 984) from their observations under thunderstorm conditions.

Using a realistic model for the electric field build-up that takes into account detrapping processes in insulating materials irradiated by electrons, a Monte Carlo approach has been applied to ground-coated binary oxides such as Al₂O₃ and Nb₂O₅. Changes entailed by the internal electric field build-up on the generation of the characteristic x-ray quanta and also on backscattered electron emission are investigated. The results clearly show that the depth distribution of characteristic x-ray production is modified and the Φ(ρz) function for both metal and oxygen K_α lines is compressed towards the surface while the backscattering electron emission is roughly unchanged. The change of the x-ray intensities as a function of the electric field is clearly established. The outcome is checked experimentally by measuring simultaneously the trapped charge and the emitted x-ray spectra during electron irradiation.

Boron carbides fabricated via plasma enhanced chemical vapour deposition from different isomeric source compounds with the same C₂B₁₀H₁₂ closo-icosahedral structure result in materials with very different direct (optical) band gaps. This provides compelling evidence for the existence of multiple polytypes of C₂B₁₀ boron carbide and is consistent with electron diffraction results.

Dielectric properties of perovskite solid solutions in the (1 − x)PbMg_1/3Nb_2/3O₃–xPbAl_1/2Nb_1/2O₃ system synthesized under high pressure and high temperature were studied. It has been found that the dielectric response of the high-pressure ceramics with x < 0.2 changes from two-phase behaviour to a solely relaxor one when annealing at elevated temperatures. The dielectric response of the ceramics and its evolution are considered in terms of an ordering action of the high-pressure synthesis and the opposite effect of the annealing process. The peculiarities of dielectric characteristics indicate the morphotropic phase boundary in the system at about x = 0.2. The local symmetry of the polar regions at the ranges above and below the boundary is discussed.

Single edge notched beams of two nuclear graphites were oxidized in CO₂ at 900°C up to 49% burn-off for IM1-24 graphite and up to 12% burn-off for PGA graphite, and fracture properties K_Ic, γ_wof and G_Ic were measured as a function of oxidation. Property decrements as a function of burn-off were fitted to an exponential decay curve (the Knudsen equation) characterized by a decay parameter, b. For both graphites oxidized to the same extent, the decrements in γ_wof and G_Ic are less than for the stress-based parameter K_Ic. The more severe decrements for K_Ic are probably because critical flaws of high aspect ratio influence this toughness parameter, whereas the energy-based toughness parameters are influenced by a spectrum of pores of different sizes and shapes. For IM1-24 graphite, crack propagation makes an increasing contribution to the total work of fracture upon oxidation due to growth in the process zone size ahead of the crack tip. The anisotropy of PGA graphite is reflected in the values of Q₀ for the three properties parallel and perpendicular to the extrusion direction, but there is no clear evidence for anisotropy in the exponential decay parameter, b. This may indicate that processes that occur in the more isotropic binder phase rather than the anisotropic filler particles dominate fracture.

Theoretical starting points and methods leading to the creation of a consistent database of thermodynamic properties of individual substances are given. The database is easy to modify and update. An exact definition of the concept consistent is given after all the relations and connections have been given. The proposed general methods are realized using computer programs and the species file, in which the thermodynamic properties of 326 gaseous and 34 condensed substances are stored that were prepared from a set of elements . Together with other files and programs the species file forms the database system TheCoufal, which is described in detail below, and stored as from the date of publication of this paper at the address http://www.feec.vutbr.cz/~coufal/.

A photoemission electron microscope activated by a 100 ps Nd : YAG laser was used to observe the spatial distribution of photoemitted electrons from Pb(111) by linear photoemission, using pulses with λ = 266 nm, and nonlinear photoemission with λ = 1064 nm. For excitation with λ = 1064 nm, the images show localized enhanced photoemission forming the previously observed hot spots, which are attributed to structural defects on the surface. Considerable enhancement of nonlinear photoemission was observed near the laser melting threshold of Pb producing intense bright regions. These bright regions increase rapidly in size and intensity as the melting threshold is approached and are interpreted as areas of local surface melting.

In a recent paper (Santillán et al2001 J. Phys. D: Appl. Phys.34 2068–72) the local stability of a Curzon–Ahlborn–Novikov (CAN) engine with equal conductances in the coupling with thermal baths was analysed. In this work, we present a local stability analysis of an endoreversible engine operating at maximum power output, for common heat transfer laws, and for different heat conductances α and β, in the isothermal couplings of the working substance with the thermal sources T₁ and T₂ (T₁ > T₂). We find that the relaxation times, in the cases analysed here, are a function of α, β, the heat capacity C, T₁ and T₂. Besides, the eigendirections in a phase portrait are also functions of τ = T₁/T₂ and the ratio β/α. From these findings, phase portraits for the trajectories after a small perturbation over the steady-state values of internal temperatures are presented, for some significant situations. Finally, we discuss the local stability and energetic properties of the endoreversible CAN heat engine.

The decomposition of volatile organic compounds (VOCs)—six aromatic compounds of benzene derivatives and formic acid—was investigated using a plasma-driven catalysis (PDC) system at atmospheric pressure. In the PDC reactor, the decomposition efficiency of VOCs was mostly determined by the specific input energy (SIE) and insensitivity to the gas hourly space velocity from 11 000 to 55 000 h⁻¹. Formic acid (HCOOH) was formed as a common intermediate from the decomposition of the tested aromatic compounds. Formic acid was also found to be an important intermediate for CO₂ formation. Except for styrene, all the tested VOCs indicated zero-order kinetics, which confirm the dominant role of the catalytic reaction in the decomposition of VOCs using the PDC reactor. A simple kinetic model represents well the observed zero-order kinetics with respect to the SIE. Unlike conventional plasma reactors, no correlation between the ionization potential and the decomposition was found with the PDC reactor. Continuous operation tests indicated stable performance without deterioration of catalytic activity over 150 h.

A numerical model has been developed to predict the shape and size of the raceway zone (a void space) created by the force of the blast air injected through the tuyeres in the packed coke bed of a blast furnace. The model is based on the solution of conservation equations of both gas and solid phases as interpenetrating continua on a Eulerian–Eulerian frame. A modified k–ε model has been adopted for gas phase turbulence. The solid phase constitutive equation is characterized by the solid pressure, bulk viscosity and shear viscosity, which are evaluated from the kinetic theory of random motions of granular materials in a fluid flow. The influences of the air blast velocity, initial porosity of the coke bed and the bed height on the shape and size of the raceway zone have been predicted.

Low temperature silicon-to-silicon wafer bonding has been successfully performed using a sol–gel intermediate layer, with bond strengths of up to 35 MPa at a bonding temperature of 100°C, which is near the fractured strength of the bulk silicon. The bonding mechanism for this low temperature sol–gel intermediate layer wafer bonding is found to be related to the surface smoothness, porous intermediate layer and high density of OH groups, and the small amount of absorbed water on the sol–gel coating prior to bonding.

The use of a device consisting of alternating layers of high and low refractive index porous silicon, arranged as a Fabry–Perot cavity, as an inexpensive and miniature refractometer is investigated. The position of the reflectance minimum depends on the pore structure as well as on the material filling the pores. We show that the presence of an interfacial layer at the internal silicon surfaces plays a crucial role in determining the quantitative relationship between the position of the reflectance minimum (i.e. the optical output of the device) and the refractive index of the medium filling the pores (i.e. the material whose presence is being sensed). The intended application of the device is in chemical and possibly biological sensing rather than in the accurate absolute determination of refractive indices.

In this paper, nanocrystalline Ni–Co alloys with continuously graded composition and structure were produced by the electrodeposition method. The internal stress of the graded Ni–Co nanocrystalline alloys generated during the electrocrystallization and the tribological properties were investigated and compared with Ni–Co alloys with a uniform structure. The results show that with continuous changes in composition and structure, the internal stress generated during the electrodeposition process was decreased to approximately the minimum level. Additionally, the graded Ni–Co nanocrystalline alloys exhibited a remarkably improved wear resistance and a much lower friction coefficient compared with the Ni–Co alloys with a uniform structure under the dry sliding wear conditions. And the graded Ni–Co nanocrystalline alloys retain perfect friction and wear properties as the annealing temperature increases up to 400°C.

The influence of the dielectric properties of spheres on the field-induced interspherical force is reported. We found that a higher dielectric constant gives rise to stronger interaction forces between dielectric spheres in a pair of barium titanate spheres at the Curie temperature where the abnormal dielectric property exists. The experiment indicates that, at the Curie temperature, there is an obvious peak in the interaction force due solely to the changes in the dielectric constant. In addition to the sphere's dielectric property, the dielectric property of the surrounding medium is a critical parameter associated with the interaction force between dielectric spheres. In addition, the interaction force is dependent on the frequency of the electric field.