The properties of Pb
5Ge
3O
11: Cu
2+ crystals near the temperature of the ferroelectric phase transition are discussed in terms of a phenomenological approach.
Assuming a quadratic interaction with the order parameter, the effect of Cu
2+ is considered a result of static distortions, which result from the off-center position of the copper impurity ions in the
lead germanate structure. In this approximation, Cu
2+ jumps between off-center positions do not affect the dynamic properties of the crystal matrix near
T
C.
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Translated from Fizika Tverdogo Tela, Vol. 42, No. 12, 2000, pp. 2187–2189.
Original Russian Text Copyright © 2000 by Trubitsyn, Pozdeev.