La掺杂Ca 2FeMo 6双钙钛矿材料制备与研究.docx

田航 田航 兰州大学硕士论文 Abstract There has bccn a great deal of interest and studies in double perovskite A2B B’06(A=divalent cati0璐；B’=transition metals；B”=non-magnetic cation，such as Mo，W Rc ctc．)，due to thehhigll Curie temperature，and the low field magnctoresistancc at room temperature，and their potential applications．In recent ycars，the researches mainly focus two aspects：(1)properties of double perovskite with different cations at A or B sites；(2)doping effects in A or B sites． When one trivalent cation substitute the divalent cation at A site，there will he a redundant electron at B site．Where the electron occupied affects the exchange interaction between the cations of B’and B’。and the hyperfine p甜amete砖of B’， thus it affects the properties of the material．Therefore，it is essential to research the cation of A site replaced by other metallic ions in double perovskite materials．In this paper，we research the effect of La ions replacing Ca ions on properties of double perovskite material．A few main results are listed as folloWS： 1．The sol—gel method Was used to prepare pure double perovskite Ca2FeM006 samples under different reaction conditions and to prepare Ca2．xLaxFeM006(x=0～0．8)．The x-ray refinements shows that the crystal structure of samples still maintain the monocline with the space group of P21／n． But the cell parameters and the anti—site defcct is increasing with x． 2．The magnetic properties measurement indicates that Ms decreases with the increasing of x due to the increasing of anti-site defect and the magnetic moments of MO． Keywords：double perovskite，Ca2FeM006，magnetism，anti-site defect，Half metals Ⅱ 原创性声明本人郑重声明：本人所呈交的学位论文，是在导师的指导下 原创性声明 本人郑重声明：本人所呈交的学位论文，是在导师的指导下 独立进行研究所取得的成果。学位论文中凡引用他人已经发表 或未发表的成果、数据、观点等，均已明确注明出处。除文 中已经注明引用的内容外，不包含任何其他个人或集体已经发表 或撰写过的科研成果。对本文的研究成果做出重要贡献的个人和 集体，均已在文中以明确方式标明。 本声明的法律责任由本人承担。 论文作者签名．＼旦墨型 E1 关于学位论文使用授权的声明本人在导师指导下所完成的论文及相关的职务作品，知识产 关于学位论文使用授权的声明 本人在导师指导下所完成的论文及相关的职务作品，知识产 权归属兰州大学。本人完全了解兰州大学有关保存、使用学位论 文的规定，同意学校保存或向国家有关部门或机构送交论文的纸