Electrical properties of non-irradiated and X-irradiated LiH and LiD

Abstract

Various electrical properties of LiH have been experimentally studied by means of the following techniques: (1)d.c. conductivity, (2)dielectric loss and (3)ionic thermocurrents (ITC).

1) The study of d.c. conductivity has been extended up to the corresponding melting points of LiH and LiD. The migration enthalpies of the cation vacancy motion and the formation enthalpies per Schottky defect have been determined.

2) The dielectric loss spectrum of O₂ X-irradiated LiD crystal doped with Mg⁺² is studied and compared with the spectrum of the non-irradiated crystal. It is found that the X-irradiation produces a decrease of the d.c. conductivity but it does not affect the dipolar contribution to the imaginary part of the dielectric constant. The results are discussed in the frame of various centers that are possibly formed upon irradiation.

3) The ITC-spectra of LiH doped with Ca⁺² and LiD doped with Mg⁺² were measured from liquid nitrogen to room temperature. A computer analysis of the depolarization current leads to the values of the migration enthalpies for the bound defect motion. The preexponential frequencies are found to be three to four orders of magnitude smaller than the Debye frequency.