La0.70Ca0.30–xSrxMnO3薄膜的制备及磁卡效应

Preparation and Magnetocaloric Effect of La_(0.70)Ca_(0.30–x)Sr_xMnO_3 Thin Films

采用溶胶–凝胶旋涂法在Si基片上生长La0.70Ca0.30–x Srx MnO3(x=0,0.05,0.10,0.15)薄膜材料。利用X射线衍射仪、原子力显微镜、场发射扫描电子显微镜和振动样品磁强计对薄膜的结构、形貌、膜厚、Curie温度和磁卡效应进行了研究。分析了Sr含量对薄膜磁性能和磁卡效应的影响。结果表明,薄膜为单相正交钙钛矿结构,薄膜表面平整致密,均方根粗糙度约为2.3 nm,薄膜厚度约为260 nm。在室温条件下,随Sr含量增加,薄膜的磁性由顺磁性转变为铁磁性,Curie温度和最大磁熵变均向高温移动。当x=0.15时,薄膜在299 K时的最大磁熵变达到16.04 mJ/(cm3 K),有较好的室温应用前景。

Thin films of La0.70Ca0.30-xSrxMnO3 （x=0, 0.05, 0.10, 0.15） were grown on silicon substrate by a sol-gel spin-coating method. The structure, morphology, film thickness, Curie temperature and magnetocaloric effect of the thin films were investigated using X-ray diffractometry atomic force microscopy, field emission scanning electron microscopy and vibrating sample magnetome-try, respectively. The influence of Sr content on the magnetic properties and magnetocaloric effect of the thin films were analyzed. The results show that this material is a single-phase structure of orthorhombic perovskite. The surface of the thin films appears smooth and dense. The root mean square roughness of the thin films is 2.3 nm. The film thickness measured is 260 nm. The magnetic property at room temperature exhibits a transition from ferromagnetic to paramagnetic, and the Curie temperature and the maximum magnetic entropy change of thin films both shift to higher temperature when the Sr content increases. The magnetic entropy change of La0.70Ca0.30-xSrxMnO3 with x=0.15 reaches 16.04 mJ/（cm3·K） at 299 K as a maximum value, which has the promising application at room temperature.