EPR and Dielectric Properties of Pb₅Ge₃O₁₁ Crystals
with Off-center Cu²⁺ Ions

M. P. Trubitsyn*, S. Waplak**, and A. S. Ermakov*

* Dnepropetrovsk State University, pr. Gagarina 72, Dnepropetrovsk 10, 320625 Ukraine

e-mail: elf@ff.dsu.dp.ua

** Institute of Molecular Physics, Poznan, Poland

Received December 28, 1999

Abstract—The electron paramagnetic resonance (EPR) and dielectric properties of Pb₅Ge₃O₁₁ crystals acti-
vated by copper ion are investigated. It is shown that Cu²⁺ ions replace Pb²⁺ in trigonal symmetry positions and
occupy three off-center positions displaced from a crystal lattice site in a plane perpendicular to the polar axis
C. The temperature variation of EPR spectra and dielectric properties indicates the presence of thermally acti-
vated jumps of Cu²⁺ ions between off-center positions. The EPR and dielectric data are used to determine the
activation energy W = 0.24 eV and the eigenfrequency ~ 10¹² Hz of local dynamics of Cu²⁺ ions. © 2000
MAIK “Nauka/Interperiodica”.

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