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.
出处
《内蒙古师范大学学报（自然科学汉文版）》
CAS
北大核心
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)
关键词
钙钛矿锰氧化物
磁性
电性
磁有序转变温度
perovskite-type manganites
magnetic property
electrical property
magnetic order tran-sition temperature
