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·K), is obtained near its Curie temperature (277 K) under the field of 1 T for La0.67-xCa0.33MnO3 (x=0.02) sample.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2004年第3期332-336,共5页
Chinese Journal of Materials Research
关键词
无机非金属材料
锰钙钛矿
磁致冷
磁热效应
磁熵变
Magnetic field effects
Magnetization
Manganese compounds
Perovskite
Polycrystalline materials
Sol
gels
Transmission electron microscopy
X ray diffraction analysis
