【摘要】 用Ｓｏｌ－Ｇｅｌ法合成了ＬａＭＯ＿３（Ｍ＝Ｆｅ，Ｃｒ，Ｍｎ，Ｃｏ）超微粉末．Ｘ射线衍射分析表明，不同焙烧温度下所合成的化合物均为单相．ＳＥＭ分析表明，粒子呈球形，室温电阻率测量表明，电阻率随粒度的变化呈两种类型：ＬａＦｅＯ＿３，ＬａＣｒＯ＿３随粒度的增大，电阻率增加；而ＬａＭｎＯ＿３，ＬａＣｏＯ＿３随粒度的增大，电阻率减小．更多还原

【Abstract】 LaMO₃（M = Fe,Cr,Mn,Co）ultrafine powders were prepared with sol-gel method.XRD showed that thecompounds prepared are single phase. SEM indicated that the particles are spherical in shape. It was foundthat the change of the resistivities with particle sizes has two types at room temperature. For LaMO₃（M=Fe,Cr）,the resistivities increase with the increase of particle sizes;while for LaMO₃（M=Mn,Co）,the resistivi-ties decrease with the increase of particle sizes.更多还原