UNSPECIFIED. (1999) Structure, oxygen stoichiometry and electrical conductivity of LnPrO(3+y) (Ln = Y and Lanthanide) oxides. MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY, 58 (3). pp. 215-220. ISSN 0921-5107

Abstract

The crystal structure and d.c. electrical conductivity of a series of homogeneous mixed rare-earth oxides in LnPrO(3+y) (Ln = Y and lanthanide ion) system are reported. It is found that the ionic size of Ln determines the crystal structure of the oxides in this series. LaPrO3+y and CePrO3+y crystallise in the fluorite structure(fcc), whereas the remaining oxides adopt the C-type rare-earth oxide structure. The electrical conductivity measurements show that conductivity is structure type dependent with the fluorites (wherein Ln = La) having a lower conductivity than the C-type mixed oxides (wherein Ln = Gd, Sm, Ho, Er and Y). The conductivity of the mixed oxides at 1020 K, is of the order of 10(-2) Ohm(-1) cm(-1) which is about five orders of magnitude higher compared to their room temperature conductivity. Oxygen excess in these compositions has been determined from wet-chemical analysis and temperature programmed oxygen evolution studies. The mixed oxides evolve oxygen in two distinct stages and the conductivity-temperature plot shows discontinuities corresponding to the onset of oxygen evolution. (C) 1999 Elsevier Science S.A. All rights reserved.

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