LaMnO3の焼結におよぼす酸化物添加の影響

概要

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The effects of oxide additives on the sintering of LaMnO3 have been discussed on the basis of the isothermal shrinkage, bulk density and grain size at 1300-1450°C for 0.25-70 hr in air. The lattice constants of LaMnO3 with various oxide additives were measured by X-ray diffraction analysis with the internal standard of 99.99% Si. The results were summarized as follows; (1) It was shown that sintering was markedly promoted by the addition of ZrO2, ZnO and BaO, while it was not promoted by the addition of Fe2O3 and TiO2 in low temperature range. (2) The results of shrinkage measurement of pure LaMnO3 and modified LaMnO3 with various oxide additives indicated that a constant value of m obtained in the initial stage was about 0.50. (3) The rate of grain growth was found to be followed by the equation Dn-D0n=kt; the values of time exponent n for pure LaMnO3 with TiO2 and CaO additives of 5 mol% were about 2.5, 2.3 and 2.6, and the values of the activation energy were estimated to be 76, 63 and 78 kcal/mol, respectively. (4) LaMnO3 and LaMnO3 with oxide (ZrO2, ZnO and BaO) additives were determined to be perovskite type with orthorhombic unit cell by X-ray diffraction analysis. It was recognized that lattice constants of LaMnO3 were varied by oxide additives up to 10 mol%.
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