ABO3 and ABX3 Crystals

摘要: In this chapter the phonon data of all measured perovskitic crystals are collected together with other which belong to chemical brutto formula ABX3 (X = O,H,F). This, unavoidably, includes so-called molecular like NaNO3 but may be justified from a technical point view. Since these show many different types phase transitions complex dielectric and anharmonic behavior it is not surprising that lattice dynamics them very complicated offers unsolved problems. An exception cubic perovskites where pioneering work COWLEY [14.12] STIRLING [14.11] led basic understanding interatomic forces in substances. A recent microscopic model [14.7, 8] emphasized importance oxygen polarizability for ferroelectric transition ABO3 perovskites.