稀土掺杂钙钛矿锰氧化物(La_(0.975)Gd_(0.025))_(4/3)Sr_(5/3)Mn_2O_7的磁性和电性研究  

Magnetic and Electric Properties of Perovskite Manganites(La_(0.975)Gd_(0.025))_(4/3)Sr_(5/3)Mn_2O_7

作　　者：王文清[1] 王志国[1] 周敏[1] 郑琳[1] 金香[1] 张雪峰[2] 赵建军[1] 

机构地区：[1]包头师范学院物理科学与技术学院,内蒙古包头014030 [2]内蒙古科技大学内蒙古自治区白云鄂博矿多金属资源综合利用重点实验室,内蒙古包头014010

出　　处：《内蒙古师范大学学报（自然科学汉文版）》2015年第1期39-43,共5页Journal of Inner Mongolia Normal University(Natural Science Edition)

基　　金：国家自然科学基金资助项目(11164019);内蒙古自治区高等学校科学研究项目(NJZZ11166;NJZY12202);包头市科学技术局产学研合作项目(2014X1014-01);包头师范学院青年科技基金项目(BSYKJ2013-23;BSYKJ2014-22;BSYKJ2014-23)

摘　　要：采用传统的高温固相反应法,制备了钙钛矿锰氧化物(La0.975Gd0.025)4/3Sr5/3Mn2O7多晶样品,利用X射线衍射(XRD)仪、物性测量系统(PPMS)和超导量子磁强计(SQUID)研究了样品的结构、磁性和电性,结果表明:该多晶样品为Sr3Ti2O7型四方结构,空间群为I4/mmm;样品的三维铁磁有序转变温度T3 DC和二维铁磁有序转变温度T2 DC分别为110K和240K,在居里温度(T3 DC)附近出现明显的磁熵变,当外磁场为2.5T时,其磁熵变值为3.1J/kg·K;电性测量结果显示,T3 DC也是样品经历金属性到绝缘性转变的温度,当T3 DC<T<300K时,样品遵循三维变程跳跃的导电方式,说明样品中载流子的输运过程是由磁不均匀性决定的.（La0.9 7 5 Gd0.02 5 ）4/3 Sr5/3 Mn2 O 7 polycrystalline sample was prepared by traditional solid state reaction method and structure,magnetic and electrical properties were investigated by measuring the M-T curve,M-H curve and R -T curve.Experimental results suggest the sample structure is Sr3 Ti2 O 7-type and its space group was I4/mmm.It transform from the two-dimensional short-range ferromagnetic order at T 2 D C to the three-dimensional long-range ferromagnetic state T 3 D C .In addition,the magnetic entropy change under 2.5 T magnetic field is up to 3.1 J/（kg＆#183;K）,which occurred near the Curie temperature.It can be seen from the fitted R-T curves that the electron conducting mechanism in the temperature range of 1 10 K＆lt;T ＆lt;300 K is in accordance with three dimensional variable range hopping conduction.

关 键 词：钙钛矿锰氧化物 磁性 电性 磁有序转变温度 

分 类 号：O482.52[理学—固体物理] O614.33[理学—物理]