烧结温度对La_(1.2)Sr_(1.8)Mn_2O_7结构和磁性的影响

Effect of Sintering Temperature on the Phase Stability and Magnetic Properties of La_(1.2)Sr_(1.8)Mn_2O_7

采用溶胶-凝胶法在不同的烧结温度下制备了La1.2Sr1.8Mn2O7多晶样品.磁性测量表明,1 200℃热处理的样品存在3个磁转变温度,且在116 K～365 K温区范围内磁化强度显著高于1 400℃热处理的样品;同时,1 400℃热处理的样品,在整个温区只存在2个磁有序转变温度,并且呈现出类自旋玻璃态.结合这2个样品的结构分析发现,较高温度处理更有利于双层钙钛矿结构的形成.

La1.2Sr1.8Mn2O7 bluk samples are prepared under various anneal temperatures by sol-gel reaction.Magnetic properties measurements show that three magnetic transition temperatures are found in the sample annealed at 1 200℃,and the magnetization much higher at 116-365 K temperature range than the sample annealed at 1 400℃.For the sample annealed at 1 400℃,the magnetization exhibits the cluster-spin-glass behavior,and only two magnetic transition temperatures are found from high temperature to low temperature.With the structure analysis of the two samples,we consider that higher anneal temperatures are propitious to the form of layered manganites.