FACTORS AFFECTING THE SINTERING AND THE ELECTRICAL-PROPERTIES OF SR-DOPED LACRO3

Sr-doped samples of lanthanum chromite have been synthesized by addition (LaSr(x)CrO3) and by substitution (La1-xSr(x)CrO3) up to x = 0.2. The influence of sintering temperatures up to 1600-degrees-C, of sintering time, of atmosphere and of particle size on the densification and on the electrical conductivity of both series was investigated. High relative densities (0.95) and high electrical conductivities (>1 OMEGA-1 cm-1) can be obtained at T < 1600-degrees-C and in oxidizing atmosphere provided that: (i) x > 0.1, (ii) the La+Sr/Cr ratio is greater than 1, (iii) the LaCrO3 particles are submicronic. Emphasis is placed on the effect of alumina introduced in the samples by vibratory milling. The subsequent alteration of the electrical properties in the La1-xSr(x)CrO3 samples is explained on the basis f of a careful microanalysis of the chromite and secondary phases by SEM and EDAX.