The Electric Field Gradients at the Sites of ^<23>Na in Ferroelectric AgNa(NO_2)_2

概要

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Electric field gradients (EFG) at Na sites in ferroelctric AgNa(NO_2)_2 have been calculated on the basis of a point charge model. The electric charge distribution in N and O atoms in NO_2 molecules was calculated by assuming perfect ionicity of AgNa(NO_2)_2 crystal. Crystallographic positions for A and B sites of the EFG in the ferroelectric phase have been assigned by a lattice sum. By representing the charge of NO_2- ion by a point charge -e at the middle point of O-O line, the largest component of the EFG tensor of fictitious perfectly ordered state (Φ^O_<xx>(T)) and that of the fictitious disordered state (Φ^D_<xx>(T)) have been calculated as functions of temperature. The observed EFG is represented fairly well by the relation Φ^<ob>_<xx>(T)=Φ^d_<xx>(T)+(Φ^O_<xx>(T))S(T).
社団法人日本物理学会の論文
1974-08-15