Tb_3Fe_(29-x)Cr_x的穆斯堡尔谱研究及其中Cr的优先占位问题的讨论

A Systematic Investigation on Mossbauer Spectrum and Preferential Occupation Fe Site by Cr in the Novel Compounds Tb_3Fe_( 29-x)Cr_x

本文系统研究了在新型化合物Tb3 Fe2 9 xCrx(x =1 0 ,1 2 ,2 0 ,3 0 )中各晶位在不同温度下的同质异能移、四极分裂、超精细场及Cr原子的优先战位问题 .我们的研究方法是先用ATOM程序绘制了Tb3 Fe2 6 0 Cr3 0 的晶位结构图和各晶位近邻配置图 ,计算出近邻原子间的键长 ,在仔细研究了Tb3 Fe2 6 0 Cr3 0 晶体结构的基础上 ,制定了穆斯堡尔谱拟谱方案研究结果表明Tb3 Fe2 9 xCrx 中Cr原子的含量x =1 0 ,1 5时Cr优先替代 4i晶位的铁 ,当Cr的含量x =2 0 ,3 0时Cr优先替代 8j晶位的铁 .Tb3 Fe2 9 xCrx 超精细场随x由 1 0增加到 3

A systematic investigation on Is.,Qs.,Hf.and the preferential occupation Fe site by Cr at different temperatures of the novel compounds Tb 3Fe 29-xCr x(x=1 0,1 5,2 0,3 0) has been performed.A illustration of crystallographic structure and the nearest neighour configuration of Fe sites for Tb-3Fe 26.0Cr 3.0 were given by ATOM program,and the bond length among the nearest neighours atoms are obtained.A scheme for fitting Mossbauer spectrum is made on the basis of the crystallographic structure and its nearest neighbour Configuration of the Tb 3Fe 29-xCr x.Mossbauer spectrum of these samples are carried out.The hyperfine field of Tb 3Fe 29-xCr x decreases gradually from x=1 0 to 3 0.The preferential occupation Fe site by Cr in Tb 3Fe 29-xCr x is investigated by means of Mosssbauer spectrum method,the results indicate that the Cr atom preferentially replaces Fe on 4i site.When the Cr content,x,is less than or equal to 1 5 the Cr atom does on 8j site for Fe when the Cr content is larger than 1 5.