我们利用固相反应法制备了粉末状La0.8Ca0．2MnO3样品，其空间群为pnma，样品中存在超顺磁性粒子，其截止态和超顺磁态的转变温度为185K，从dσ/dT的负峰得到铁磁一顺磁相变居里温度为210K，在顺磁领域线性拟合而得到顺磁居里温度为216．4K，分子式有效磁矩为6．25μB，低温领域磁化曲线服从布洛赫T^3/2定律，其自旋波劲度系数为49．2meVA^2．
The La0. 8Ca0.2MnOa powder specimen prepared by solid state reaction method, which has pnma space group. Superparamagnetic particles were found in the specimen, the transition temperature TB from blocking state to superparamagnetic state is 185K and ferromagnetic-paramagnetic phase transition Curie temperature,Tc , is 210K obtained from negative peak temperature of dσ/dT. The paramagnetic Curie temperature 216.4K was given by linear fitting in paramagnetic regime. The molecular effective magnetic moment is 6. 25μB and at the low temperature range the magnetization curve is observed to obey the Bloch law, spin wave stiffness constant were obtained to be 49.2 meVA^2.
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