Preparation of pseudotetragonal ZrO0.75S and its electric responses on temperature and frequency related to microstructural relaxation

Abstract

Pseudotetragonal ZrO0.75S whose space group is P212121 was synthesized and the cell dimensions were a=5.110(2) Å, b=5.110(7) Å, and c=5.198(8) Å. The space group P212121 seems to be resulted from lowering the symmetry of cubic ZrOS structure with P213 space group by lattice distortion due to the oxygen defects. In the distorted structure, bond shortening between metal-nonmetal by reduction of cell volume and alternation of Zr-Zr distance were observed. Dielectric constant and loss data of the bulk material in temperature range -170 to 20 °C and frequency range 50 Hz to 1 MHz showed that there was dielectric transition at around -70 °C originated from the relaxation of Zr-S segment. Comparing with ZrO2 exhibited the dielectirc constants, 9.0 at room temperature, ZrO0.75S showed high dielectric constant, k = 200.2 at 100 kHz. The activation energy of relaxation time due to dielectric relaxation of Zr-S was 0.47 eV (11.3 kcal/mole). According to the impedance spectra, ZrO0.75S showed more parallel circuit character between the resistance and capacitance components at the temperature (-70 °C) that the Zr-S dielectric relaxation was observed.