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采用溶胶-凝胶(sol-gel)法制备了名义组分为La0.67Sr0.20Cu0.10□0.03MnO3(□代表阳离子空位)的多晶样品母体粉体材料,在400℃下氢气环境中对母体材料进行还原处理。在不同温度下于空气中烧结不同时间得到系列块体样品。研究了热加工条件对粉体以及块体样品居里温度的影响。结果表明,发现粉体样品和块体样品的居里温度相差不多,但是随着温度的降低,块体样品的比磁化强度迅速增大,粉体样品的比磁化强度却增加缓慢;与块体样品相比,粉体样品的比磁化强度随温度降低而增加缓慢的主要原因是粉体样品晶粒小,晶粒表面原子占原子总数的比例大,而表面原子的结合较弱。
A polycrystalline sample precursor powder material with the nominal composition of La0.67Sr0.20Cu0.10 □ 0.03MnO3 (□ represents the cationic vacancy) was prepared by the sol-gel method under hydrogen atmosphere at 400 ° C The parent material is reduced. At different temperatures in the air sintering at different times to obtain a series of bulk samples. The effect of thermal processing conditions on the Curie temperature of powder and bulk samples was investigated. The results show that the Curie temperature of the powder sample and the bulk sample are similar, but the specific magnetization of the bulk sample increases rapidly with the decrease of temperature, but the specific magnetization of the sample increases slowly; The main reason that the specific magnetization decreases with temperature is that the grain size of the sample powder is small, the proportion of atoms on the surface of the grains to the total number of atoms is large, and the binding of the surface atoms is weak.