The effects of oxide additives on the sintering of LaMnO
3 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 LaMnO
3 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 ZrO
2, ZnO and BaO, while it was not promoted by the addition of Fe
2O
3 and TiO
2 in low temperature range. (2) The results of shrinkage measurement of pure LaMnO
3 and modified LaMnO
3 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 LaMnO
3 with TiO
2 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) LaMnO
3 and LaMnO
3 with oxide (ZrO
2, 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 LaMnO
3 were varied by oxide additives up to 10 mol%.
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