Electrical conductivity and defect structure of the Th xLu 2−2xO 3−x solid solutions

Abstract

Th x Lu 2−2 x O 3− x solid solutions containing 1, 3, 5 and 7 mol %ThO 2 were synthesized with spectroscopically pure Lu 2O 3 and ThO 2 into polycrystallinc powders. X-Ray spectroscopy revealed that all the synthesized specimens have the rare earth-type cubic structure, and that the lattice parameter of Lu 2O 3 increases with increasing doping level. Electrical conductivities were measured as a function of temperature from 600 to 1100°C and of p o2, from 10 −6 to 2 × 10 −1 atm. The defect structure and the electrical conduction mechanisms were deduced from the results. The 1/ n values in σ ∞ P 1 n o 2 are 1 n = 1 6 and 1 n = 0 at P o 2 s higher and lower than 10 −4 atm, respectively. From the variation of the 1 n values from 1 n − 0 to 1 n = 1 6 , ionic and electronic conduction mechanisms are suggested in the low- and high-oxygen partial pressure regions, respectively, with two possible defect models.