LaCrO_3－NiMn_2O_4复合陶瓷的结构分析

STRUCTURAL ANALYSIS OF LaCrO_3-NiMO_2O_4 COMPOSITE CERAMICS

将尖晶石型ＮｉＭｎ＿２Ｏ＿４及钙钛矿型ＬａＣｒＣ＿３这二者电阻个较高的半导体陶瓷热敏材料复合并经高温烧结后，其复合体电阻率大幅度降低。应用ＸＲＤ，ＸＰＳ，ＴＥＭ和ＳＥＭ对复合体结构进行较为系统的研究，结果表明：ＮｉＭｎ＿２Ｏ＿４与ＬａＣｒＯ＿３按一定比例复合后，在烧结过程中两者之间有离子迁移发生，离子迁移的结果使钙钛矿结构的ＬａＣｒＯ＿３转变为高导电相的Ｌａ［Ｃｒ＿（１－ｘ－ｙ）Ｎｉ＿ｘＭＮ＿ｙ］Ｏ＿３（０＜ｙ＜０，０＜ｘ＋ｙ＜０），它使复合体电阻率大幅度降低。

NiMn_2O_4 spinel and LaCrO_3 perovskite are semiconductive ceramic materials which have highresistivity,but the resistivity of the composite ceramics composed of NiMn_2O_4 and LaCrO_3 and sintered at hightemperature reduces significantly. By means of XRD, XPS, TEM and SEM,the microstructure of compositeceramics is studied,it is shown that ion migration exists in the composite ceramics. By ion migration,LaCrO_3perovskite structure changes into(0<x<1, 0<y<1, 0<x+y<1).which is high con-ductive crystal phase,and reduces the resistivity of composite ceramics.