INFLUENCE OF \gamma-RADIATION ON THE DIELECTRIC CHARACTERISTICS IN Rb₂ZnCl₄ SINGLE CRYSTALS AT INCOMMENSURATE-COMMENSURATE PHASE TRANSITION

In this paper the influence of \gamma-radiation on the dielectric constants of Rb₂ZnCl₄ crystal at incommensurate-commensurate phase transition (hereafter abbreviated as INC-C transition) are studied. The thermal hysteresis occurs upon both cooling and heating runs, irrespective of whether the samples have been treated with \gamma-radiation or not. For the \gamma-irradiated sample, its transition point, T_c, between the INC and C phases is not changed, but the peak value of the dielectric constant at T_c increases abruptly, compared with that before \gamma-irradiation, When this sample is annealed at 40℃, the peak value restores to the incipient value for the sample free from \gamma-irradiation. The origin of the phenomenon of the thermal hysteresis of the dielectric constant may be due to the pinning effect of dejects or impurities in the samples.