(1. 南昌大學 材料科學與工程學院，南昌330031；2. 華中科技大學 材料科學與工程學院，武漢 430074；3. 南京大學 固體微結(jié)構(gòu)國家重點實驗室，南京210093)
摘 要: 采用固相反應法制備La(1−x)2/3Ca1/3MnO3(x=0.0，0.04)和(La0.7Y0.3)2/3Ca1/3MnO3系列樣品，測量不同溫度下的磁化強度—磁場曲線，計算樣品的磁熵變，研究La空位摻雜和Y3+離子摻雜對磁熱效應的影響。結(jié)果表明，La空位摻雜(x=0.04)的樣品在居里溫度附近磁熵變最大值為6.22 J/(kg∙K)，這比La2/3Ca1/3MnO3磁熵變最大值(6.26 J/(kg∙K))稍有降低；而Y3+離子摻雜的樣品在溫度60 K時和磁場強度2 T下，其磁熵變最大值為0.568 J/(kg∙K)，并且磁熵變隨溫度變化有繼續(xù)增大的趨勢。這表明(La0.7Y0.3)2/3Ca1/3MnO3可以作為一定溫區(qū)的磁致冷材料。
關(guān)鍵字: (La(1−x−y)Yy)2/3Ca1/3MnO3化合物；固相反應；磁熱效應；磁熵變；空位摻雜
（1. School of Materials Science and Engineering, Nanchang University,Nanchang 330031, China;2. School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;3. State Key Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China）
Abstract:A series of polycrystal samples of La(1−x)2/3Ca1/3MnO3(x=0.0, 0.04) and (La0.7Y0.3)2/3Ca1/3MnO3 were prepared by standard solid-state reaction method. The curves of magnetic-field dependence on magnetization were measured at various temperatures and the entropy changes of the samples were calculated. The influences of La vacancy doping and Y3+ doping on magnetocaloric effect were investigated. The results show that the maximum value of magnetic entropy change for La vacancy doping sample (x=0.04) is 6.22 J/(kg∙K) near Curie temperature Tc, which is a little smaller than that of La2/3Ca1/3MnO3 sample. The maximum value of magnetic entropy change for Y3+ doping sample is 0.568 J/(kg∙K) at temperature of 60 K and in magnetic field of 2 T, and the magnetic entropy change increases with the increase of temperature, which indicates that the perovskite manganites are suitable candidates as working substances in magnetic refrigeration technology.
Key words: (La(1−x−y)Yy)2/3Ca1/3MnO3 compounds; solid-state reaction; magnetocaloric effect; magnetic entropy change; vacancy doping
