La_(0.67-x)Ca_(0.33)MnO_3系列样品的磁热效应  

Magnetocaloric effect of La_(0.67-x)Ca_(0.33)MnO_3

作　　者：侯登录[1] 白云[2] 徐静[2] 唐贵德[2] 

机构地区：[1]河北师范大学物理学院,教授石家庄市050016 [2]河北师范大学

出　　处：《材料研究学报》2004年第3期332-336,共5页Chinese Journal of Materials Research

摘　　要：用溶胶-凝胶法制备了不同空位浓度掺杂的La0.67-xCa0.33MnO3系列样品(x=0.00,0.02,0.06,0.10),用扫描电子显微镜(SEM)观察了样品的形态和颗粒大小,X射线衍射实验结果显示样品为单相钙钛矿结构,用振动样品磁强计(VSM)测量了样品的磁化强度随温度变化的M-T曲线和起始磁化M-H曲线.研究了空位浓度对样品的居里温度Tc和磁熵变的影响.结果表明,空位浓度的掺杂将样品的居里温度Tc提高至室温附近,磁熵变得到增强.对于经历了一级相变的样品La0.67-xCa0.33MnO3(x=0.02),在居里温度Tc(277 K)附近和1 T外磁场下,最大磁熵变达到了2.78 J/(kg·K).Polycrystalline samples of La0.67-xCa0.33MnO3 (x=0.00, 0.02, 0.06, and 0.10) with different vacancies in La3+-site were prepared by sol-gel method. The grain sizes of samples were observed by SEM. XRD results show that the samples are single phase of perovskite-type oxides. The Curie temperatures and the magnetic entropy change of the samples were studied by VSM. The influence of the vacancy concentration in La3+-site on their magnetocaloric properties has been investigated. The higher Curie temperatures close to room temperature and the larger magnetic entropy changes have been observed. The maximum magnetic entropy change, 2.78 J/(kg&middotK), is obtained near its Curie temperature (277 K) under the field of 1 T for La0.67-xCa0.33MnO3 (x=0.02) sample.

关 键 词：无机非金属材料 锰钙钛矿 磁致冷 磁热效应 磁熵变 

分 类 号：TB64[一般工业技术—制冷工程]