Thermal and X-ray studies on mixed metal oxalates - (NH4)LnIIIUIV(C2O4)4·8H2O (Ln = La, Ce, Pr, Nd Tb)
作者:K.D.Singh Mudher、K. Krishnan、A.K. Chadha、V. Venugopal
DOI:10.1016/s0040-6031(97)00068-3
日期:1997.8
Abstract Five mixed metal oxalates of lanthanides and uranium of the formula (NH4)LnIIIUIV(C2O4)4·8H2O were prepared and characterised by chemical, infrared spectroscopy, X-ray diffraction and thermal methods. The X-ray powder diffraction data of all the compounds were indexed on an orthorhombic unit cell. Thermal decomposition of the compounds proceeded with the loss of water molecules below 475 K
摘要 制备了式(NH4)LnIIIUIV(C2O4)4·8H2O 的五种镧系元素和铀的混合金属草酸盐,并采用化学、红外光谱、X 射线衍射和热法表征。所有化合物的 X 射线粉末衍射数据均以正交晶胞为索引。化合物的热分解在 475 K 以下失去水分子,然后在 625 至 655 K 的温度范围内分解,得到 Ln2O2CO3 和 UO2+x 作为中间产物。中间产物在 975 K 以上反应形成具有萤石结构的混合氧化物的固溶体。为镧和铽化合物的脱水推导出活化能值。通过在空气中加热化合物形成的混合氧化物的萤石相的晶格参数,