Phase separation and direct magnetocaloric effect in La0.5Ca0.5MnO3 manganite
Phase separation and direct magnetocaloric effect in La0.5Ca0.5MnO3 manganite
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DOI：
10.1063/1.4794179
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发表时间：
2013-03
影响因子：
3.2
通讯作者：
P. Amirzadeh;H. Ahmadvand;P. Kameli;B. Aslibeiki;H. Salamati;A. Gamzatov;A. Aliev;I. Kamilov
中科院分区：
文献类型：
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作者：
P. Amirzadeh;H. Ahmadvand;P. Kameli;B. Aslibeiki;H. Salamati;A. Gamzatov;A. Aliev;I. Kamilov
通过交流磁化率、直接磁热效应（ΔT）和热容测量，研究了一系列不同晶粒尺寸的La 0. 5Ca 0. 5MnO3相分离锰氧化物样品。交流磁化率表明，铁磁和反铁磁相的分数，从而相分离状态可以通过烧结温度控制。较低的烧结温度导致铁磁状态，而较高的烧结温度增加反铁磁相分数，导致相分离状态。在分相样品中，ΔT在TC附近出现一个常规的正峰，在TN附近出现一个反常的低温正峰。在高磁场下出现反常的正峰，并伴有热滞。认为异常磁热行为是由相分离和一级磁结构相变引起的。这项研究表明，直接磁热效应是一种有用的技术。
A series of phase separated La0.5Ca0.5MnO3 manganite samples with different grain sizes were studied by ac susceptibility, direct magnetocaloric effect (ΔT), and heat capacity measurements. The ac susceptibility shows that fractions of ferromagnetic and antiferromagnetic phases and consequently the phase separated state can be controlled by means of sintering temperature. Lower sintering temperature leads to a ferromagnetic state, while higher sintering temperature increases antiferromagnetic phase fraction, resulting in a phase separated state. In the phase separated samples, ΔT shows a conventional positive peak near TC and an anomalous positive peak at lower temperature near TN. The anomalous positive peak appears at higher magnetic field and is accompanied with thermal hysteresis. It is suggested that the anomalous magnetocaloric behaviors result from phase separation and first order magnetostructural phase transition. This study shows that direct magnetocaloric effect is a useful technique for the st...