ON THE STRUCTURE AND DYNAMICS OF HETEROVALENTLY DOPED BETA-PBF2

Heterovalent isomorphous replacement is one of the main methods to inc rease the ionic conductivity of solid electrolytes. Understanding the nature of these impurity defects and their relaxation can help in esta blishing the connection between the electrophysical properties and cry stallochemical peculiarities of doped superionic conductors. EPR spect ra of Gd3+ in PbF2 show a well resolved fine structure as well as spin forbidden transitions with Delta M(s)> 1. The angular dependence in b oth cases indicates that Gd3+ occupies a purely cubic symmetric site. This stands in contrast to earlier results and is indicative of the im portance of the history of a sample, especially its thermal and pressu re treatment, as shown by X-ray analysis and conductivity data. A meth od of investigating dipole defects and polarizing phenomena is propose d, whereby RE-F-i dipole defects are fixed and their relaxation is stu died by means of EPR-spectroscopy.