摘要
研究了具有庞磁电阻(CMR)效应的锰基钙钛矿氧化物La0.7Ca0.3MnO3(LCMO)与Al复合体系的电磁输运性质.根据X射线衍射分析及电阻率与温度的关系可知,在(1-x)LCMO+xAl(x代表物质的量)复合样品中,发现了新相Al2O3,且LCMO晶格常数和晶胞体积随Al掺量的增加而减小,同时在复合样品中出现了除对应LCMO本征金属-绝缘体转变峰TP1之外,在较低温度区域出现了另外一个转变峰TP2的现象,且复合样品转变峰TP2比LCMO本征金属-绝缘体转变峰TP1处于较宽的温度区域.经研究认为,在合成复合样品的实验过程中,既有Al被氧化为Al3+替代Mn3+的替代反应,也有Al经过高温与空气发生反应生成Al2O3,进而填隙在LCMO晶界处影响母体的电磁输运性质.本系列复合物中较宽温度区域CMR的发现为今后同类问题的研究提供了很好的实验基础.
The electrical-magnetic transport properties of manganese peroveskite oxides La0.7.Ca0.3MnO3 （LCMO） and Al composites have been investigated . According to the results of X-ray diffraction （XRD） and temperature dependence of the resistivity, and in （LCMO）1-xAlx composites （x represents the volume fraction）, we find a new phase Al2O3, the unit-cell volume and the relevant structural parameters in peroveskite structure decrease with the increasing of Al content. The samples show that another I/M transition TP2 besides the one TP1 corresponding to LCMO＇s intrinsic I/M transition. The new I/M transitions are at a lower temperature area and have a wider temperature region than the latter ones. Some Mn^3＋ substituted by Al^3＋ together with the new phase A1203 segregated at the grain boundaries of LCMO are the reason for above phenomena. The observation of CMR in wide temperature region offers a foundation for similar experimental research.
出处
《河南理工大学学报（自然科学版）》
CAS
2007年第1期99-103,共5页
Journal of Henan Polytechnic University（Natural Science）
基金
国家自然科学基金资助项目(40572025)
