嵌入化合物Fe_(0.95)PS_3(MV)_(0.11)的合成与磁性能研究  

Synthesis and magnetism of the intercalation compound Fe_(0.95)PS_3(MV)_(0.11)

作　　者：戴耀东[1,2] 何云[1] 黄红波[1] 邵挺[1] 夏元复[1] 

机构地区：[1]南京大学物理系 [2]南京航空航天大学材料科学与技术学院,南京210016

出　　处：《物理学报》2003年第12期3020-3026,共7页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :1983 5 0 5 0 )资助的课题~~

摘　　要：利用嵌入反应合成了有机 无机嵌入化合物Fe0 95PS3(MV) 0 1 1 (MV为 1,1′ 二甲基 4 ,4′ 联吡啶阳离子 ) ,对其结构和磁性进行了研究 .x射线衍射数据表明 ,此嵌入化合物的晶体结构仍为单斜晶系 ,空间群为C2 m ,晶胞参数a=0 879nm ,b=0 94 4nm ,c=1 0 70nm ,β =114 76°.相对于纯FePS3,层间距离增大 0 33nm .磁化率研究表明 ,从室温降到 4 2K过程中 ,此化合物经历了两级磁相变 .在居里温度TC =84K以下发生铁磁相变 ,奈尔温度TN =2 6K以下为反铁磁相变 .12— 30 0K变温M ssbauer谱研究证实 ,此化合物存在三个高自旋二价铁的位置 ,表明在嵌入反应过程中有电荷从客体分子转移到主体晶格中Fe—S的e g 反键轨道上 ,并有部分铁离子从晶格中脱出 ,从而在主体晶格中产生金属阳离子空位 .铁磁性是由于自旋倾斜所致 ,而极低温度下自旋倾斜消失 ,又表现为反铁磁性 .The intercalation compound Fe0.95PS3 (MV)(0.11) (MV is the methylviologen cation) has been prepared. Its crystal structure and magnetism have been investigated by x-ray diffraction (XRD), susceptibility measurements and Mossbauer experiments. Its XRD pattern can be indexed in a monoclinic unit cell with a=0.879 nm, b=0.944 nm, c=1.070 nm, beta=114.76degrees. The distance between layers of this intercalation compound is increased by 0.33 nm compared with that of FePS3. The data of susceptibility show that second-order magnetic phase transitions have occurred when the temperature changed from 300 K down to 4.2 K. A ferromagnetic phase transition occurred below T-C=84 K. An antiferromagnetic phase transition occurred below T-N=26 K. The results of Mossbauer spectra taken in the temperature range of 12 to 300 K indicate that there are three kinds of divalent ions with their high spin states, which imply a charge transfer from guest to the Fe-S e*(g) antibonding orbitals of the FePS3 host lattice, and some ions have been released from the FePS3 host lattice and then some vacancies have been formed. The ferromagnetism originates from a canting of the spins of Fe2+, whereas the antiferromagnetism occurred when the canting of the spins of Fe2+ have been modified at the lowest temperatures.

关 键 词：嵌入化合物 X射线衍射 晶体结构 铁磁相变 奈尔温度 分子磁体 分子磁学 MOSSBAUER谱 

分 类 号：O614[理学—无机化学]