Table of contents

Introduction 453 1. The Dynamic Approach to the Problem of Ferroelectricity 454 1.1. Lattice Dynamics and Stability of Non-piezoelectric Crystals 455 a) General Vibration Equations and the Condition of Structural Stability 455 b) Dielectric Properties of Crystals and Their Relation to the Characteristic Frequencies 458 c) The Physical Mechanism of the Ferroelectric Transition in Cubic Crystals 458 1.2. Application of the Theory to Crystals Having Piezoelectric Properties 451 2. The Role of Anharmonic Effects and Fluctuations and Their Manifestation in Raman Spectra 452 3. Types of Normal Vibrations of Perovskite-type Crystal Structures 463 4. Features of the Experimental Study of the Dynamics of Ferroelectric Crystals 466 4.1. Methods of Infrared Spectroscopy and Raman Scattering 466 4.2. Methods Based on Inelastic Scattering of Slow Neutrons 467 5. Results of Experimental Study of Crystal Lattice Dynamics of Ferroelectric Substances 469 5.1. Infrared Spectra 469 5.2. Raman Spectra 475 5.3. Slow-neutron Inelastic-scattering Spectra 477 5.4. On the Possibility of Studying the Dynamics of Ferroelectric Substances by Using the Mossbauer Effect 481 Conclusion 481 Bibliography 482

1. Introduction 559 2. Nuclear Fission Concepts 559 3. Spontaneous Fission of Nuclei 561 4. Cross Section for Induced Nuclear Fission 562 5. Mass Distribution of Fragments 569 6. Charge Distribution of Fragments 575 7. Angular Distribution of Nuclear Fission Fragments 578 8. Kinetic Energy of Fission Fragments 583 9. Neutrons, Gamma Quanta, and Charged Particles Emitted in Nuclear Fission 586 Bibliography 592