Deuteron Magnetic Resonance in KD₃(SeO₃)₂

Abstract

Quadrupole coupling constant and the direction of the principal axes of EFG tensor of deuterons in KD₃(SeO₃)₂ are obtained from 40 to −106°C. It is confirmed that there exist two symmetrically inequivalent deuterons D(1) and D(2), and D(1) is ordered in the disordered phase. Deuterons D(2) are found to be dynamically disordered in the disordered phase. In the ordered phase, D(1) sites are divided into two inequivalent groups while the number of D(2) sites remains unchanged. The splitting of the resonance line of D(1) in the ordered phase depends on temperature as (T_tr−T)^β, where T_tr is 24.9°C and β is about 0.52±0.08 in the temperature from 24.4 to 22°C and 0.46±0.01 from 22 to 3°C. The relation between the splitting and the order parameter is discussed.