Study on the Temperature Dependence of 87Rb Electric Field Gradients in RbDSO4 by NMR

The second order quadrupole shifts of 87 Rb nuclear magnetic resonance in single crystals of RbDSO 4 are measured from 18°C to -100°C and are analysed by Volkoff method. In paraelectric phase there are two inequivalent electric field gradients (EFG), one of which hardly shows the temperature dependence and the other increases slightly with decreasing temperature. In ferroelectric phase ( T c =-22°C) each component of the EFG tensors splits into two components. Their splittings change as ( T c - T ) β , where β for each component of the EFG tensor takes the value in the range from 0.28 to 0.39. The orientations of the principal axes of EFG in ferroelectric phase are found to change with temperature. The principal coordinate system which shows almost no temperature dependence in magnitude of the quadrupole coupling constant rotates about the principal z axis by the angle of 75° over the temperature range studied.