Sintering behavior and mechanism of Sr-doped lanthanum chromites with A site excess composition in air

Sintering characteristics and mechanisms of lanthanum strontium chromites, (La1-xSrx)(1+y)CrO3 (0 less than or equal to x less than or equal to 0.3, 0 less than or equal to y less than or equal to 0.02), in air are discussed in comparison with the results for Ca-doped lanthanum chromites. The sinterability of La0.9Sr0.1-yCrO3 increased with increasing alkaline earth (AE) content, but was much lower than that of La0.9Ca0.1+yCrO3. It was found that the ratios of AE to Cr formed a second phase in the sample in the region 0.5 < x < 3 for Ca/Cr and in the range 10 < x < 15 for Sr/Cr. The ratios of Ca to Cr entered in the composition range, forming a low melting point (greater than or equal to 1050 degrees C) system. On the other hand, the second phase formed by the Sr/Cr ratios might be in the composition range of the solid state st firing temperatures of 1600 degrees C, An attempt was made to fully sinter 10 mol% Sr-doped lanthanum chromites with 2 mol% sintering aids. After heating at 1600 degrees C in air, the relationship between the ionic field strength of the sintering aids and the relative density for La0.9Sr0.1CrO3 with 2 mol% sintering aid was clarified, With increasing ionic field strength, that is with decreasing basicity, the relative density of the doped La0.9Sr0.1CrO3 perovskites decreased. (C) 1999 Elsevier Science B.V. All rights reserved.