Ca掺杂EuMnO3体系的磁性和磁卡效应研究

Magnetic and magnetic card effect of Ca-dopedEuMnO3 system

采用传统的高温固相反应法制备了钙钛矿氧化物Eu1-xCaxMnO3(x=0,0.1,0.2,0.3,0.4,0.5)多晶体系样品。通过样品的XRD谱线、磁化强度随温度、外加磁场的变化曲线(M-T、M-H)等数据研究了Ca不同掺杂量对钙钛矿氧化物EuMnO3系列多晶样品的居里温度、磁熵变、磁相变等的影响。结果表明,Eu1-xCaxMnO3(x=0,0.1,0.2,0.3,0.4,0.5)系列陶瓷样品呈现良好的单相性,空间点群为Pnma。低浓度掺杂的样品存在一个TC,高浓度掺杂的样品出现两个磁转变点,且由于双交换相互作用,随着Ca的掺杂,TC逐渐增大,当掺杂量达到0.4时,低温下的TC却明显减小。根据-ΔSM和RCP值可知,Eu0.7Ca0.3MnO3是该组样品中比较适合做磁制冷的材料。通过对Loop曲线的分析可知该组样品经历了由一级相变向二级相变转变的过程。

The perovskite oxide Eu1-xCaxMnO3(x=0,0.1,0.2,0.3,0.4,0.5)polycrystalline system samples were prepared by traditional high temperature solid phase reaction.The effects of different Ca doping amount on Curie temperature,magnetic entropy change and magnetic phase transition of the perovskite oxide EuMnO3 series polycrystalline samples were studied by XRD lines,magnetization curves with temperature and applied magnetic field(M-T,M-H).The results show that Eu1-xCaxMnO3(x=0,0.1,0.2,0.3,0.4,0.5)ceramic samples exhibited good single-phase properties,and the spatial point group was Pnma.There was one TC in the doped sample with low concentration,but two magnetic transition points appeared in the doped sample with high concentration.Due to the double exchange interaction,the TC gradually increased with the doping of Ca.When the doping amount reached 0.4,the TC at low temperatures was significantly reduced.According to theΔSM and RCP values,Eu0.7Ca0.3MnO3 was a material suitable for magnetic refrigeration in this group of samples.Through the analysis of the Loop curve,it was known that the sample of the group underwent a transition from a first-order phase transition to a second-order phase transition.