1273 K条件下铈铁砷的交互作用研究

Study on the Interaction of Cerium,Iron and Arsenic at 1 273 K

为了进一步认识铈铁砷的交互作用及其产物,本文首先通过Miedema与离子熵模型计算了Fe2As化合物的生成热、生成熵,随后计算了Fe2As与铈铁砷三元化合物的自由能,然后将稀土铈和砷按铈砷原子比为1∶3封入自制H08钢缸体中加热至1 273 K下恒温30 h,采用光学显微镜、XRD、扫描电镜和EDS能谱微区等现代分析手段,对该条件下所得试样中铈铁砷系的交互作用及产物进行分析。结果表明:二元化合物Fe2As标准自由能计算结果为ΔG=-37 282.63-9. 54T J/mol(Fe为+3价,低自旋离子半径);当Fe2As与CeAs形成Ce12Fe57.5As41满足理想固溶体条件时,其吉布斯自由能为ΔG=-435 212.63-157.21T J/mol(Fe为+3价,低自旋离子半径);1273 K条件下铈铁砷交互作用的主要产物为CeAs、Fe2As和三元化合物Ce12Fe57.5As41,其二元化合物CeAs和Fe2As的形成是铈铁砷系三元化合物Ce12Fe57.5As41形成的基础。

To further study the interaction ofcerium,iron and arsenic,and their products,we calculated the Fe2 As compounds heat of formation,entropy of formation by Miedema and ion entropy model. Furthermore,the free energies of Fe2 As and Ce-Fe-As ternary compounds were then calculated. Then the rare earth cerium and arsenic were sealed into the H08 steel cylinder block at a ratio of 1 ∶3 and heated to a constant temperature of 30 h at 1 273 K. The interaction products of cerium,iron and arsenic in the samples obtained were analyzed by means of modern analysis methods such as metalloscope,XRD,SEM and EDS microzone. The results show that the calculated Gibbs free energy of the compound Fe2 As is ΔG =-37 282.63-9.54 T J/mol( Fe is +3 valence,low spin ion radius). When the ternary compound Ce12Fe57.5As41 formed by Fe2 As and CeAs mix the ideal solid solution condition,When the Fe is +3 valence,low spin ion radius,the Gibbs free energy ΔG =-435 212.63-157.21 T J/mol. CeAs,Fe2 As and ternary compound Ce12Fe57.5As41 are the main products for the interaction of cerium,iron and arsenic at 1 273 K,and the formation of binary compound CeAs and Fe2 As is the basis of the formation of Ce12Fe57.5As41.