Effect of calcination temperature on B-site vacancy content of La0.75Sr0.25Mn0.92△0.08O3-δ perovskite
来源期刊：Journal of Rare Earths2018年第3期
论文作者：Denghui Ji Shuling Wang Xingze Ge Xinju Xiao Liwei Wang Zhiwei Zeng Congmin Zhang
文章页码：287 - 297
摘 要：Lanthanum manganite with cation vacancies from nominal La0.75Sr0.25Mn0.92△0.08O3-δ nanocrystalline powder was successfully prepared at different calcination temperatures using the sol-gel method. X-ray diffraction shows that as the calcination temperature(TCal) increases, the crystal particle diameter increases, but the B-site vacancy content decreases. According to a powder diffraction profile fitting technique and transmission electron microscopy results, the vacancy content can be estimated as 0.08,0.01, and 0.005 for TCal = 1073,1273, and 1473 K, respectively. Magnetization versus temperature curves show that the magnetic transition temperatures, including the Curie temperature, are influenced by both B-site vacancies and double-exchange interaction between Mn3+ and Mn4+ cations. A core-shell model is proposed for vacancies located on the surfaces of the crystal particles. As an application, the magnetic moment angle θij between Mn3+ and Mn4+ cations on the surface, which decreases with decreasing vacancy content, can be obtained.
Denghui Ji1,2，Shuling Wang3，Xingze Ge4，Xinju Xiao1,2，Liwei Wang1,2，Zhiwei Zeng1,2，Congmin Zhang1,2
1. School of Electrical Engineering,Liupanshui Normal University3. School of Science of Hebei University of Engineering,Hebei University of Engineering4. Ceramic Science Institute,China Building Materials of Academy
摘 要：Lanthanum manganite with cation vacancies from nominal La0.75Sr0.25Mn0.92△0.08O3-δ nanocrystalline powder was successfully prepared at different calcination temperatures using the sol-gel method. X-ray diffraction shows that as the calcination temperature(TCal) increases, the crystal particle diameter increases, but the B-site vacancy content decreases. According to a powder diffraction profile fitting technique and transmission electron microscopy results, the vacancy content can be estimated as 0.08,0.01, and 0.005 for TCal = 1073,1273, and 1473 K, respectively. Magnetization versus temperature curves show that the magnetic transition temperatures, including the Curie temperature, are influenced by both B-site vacancies and double-exchange interaction between Mn3+ and Mn4+ cations. A core-shell model is proposed for vacancies located on the surfaces of the crystal particles. As an application, the magnetic moment angle θij between Mn3+ and Mn4+ cations on the surface, which decreases with decreasing vacancy content, can be obtained.
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