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 sinter ability of La0.9Sr0.1-yCrO3 increased with increasing alkaline earth (AE) c ontent, 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 (gre ater 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 t o fully sinter 10 mol% Sr-doped lanthanum chromites with 2 mol% sintering a ids. After heating at 1600 degrees C in air, the relationship between the i onic field strength of the sintering aids and the relative density for La0. 9Sr0.1CrO3 with 2 mol% sintering aid was clarified, With increasing ionic f ield strength, that is with decreasing basicity, the relative density of th e doped La0.9Sr0.1CrO3 perovskites decreased. (C) 1999 Elsevier Science B.V . All rights reserved.