A_2(MoO_4)_3(A=Al,Cr,Fe)结构与相变的Raman光谱研究(英文)

Raman spectroscopic study on the structure and phase transition of A_2(MoO_4)_3(A=Al,Cr,Fe)

用XRD、Raman光谱和DSC研究了Al2(MoO4)3、Cr2(MoO4)3和Fe2(MoO4)3的结构与相变。Al2(MoO4)3、Cr2(MoO4)3和Fe2(MoO4)3在室温下为单斜相,分别在483 K、673 K和783 K附近转变为正交相。发现MO4四面体的对称和反对称伸缩振动模的频率和相对强度明显受到A3+离子的影响。这些模的软化程度受A3+离子的影响依次为Fe>Cr>Al,与A3+离子半径和电负性对MO4四面体的键强和灵活性的影响密切相关。

The structures and phase transition of Al2（MoO4）3,Cr2（MoO4）3and Fe2（MoO4）3 materials have been studied by XRD,Raman spectroscopy and DSC.It is shown that Al2（MoO4）3,Cr2（MoO4）3and Fe2（MoO4）3 crystallize in monoclinic structure at room temperature and transform to orthorhombic phase at about 483 K,673 Kand 783 K,respectively.It is found that frequencies and relative intensities of the symmetric and asymmetric stretching vibrations of the MO4 tetraheda are obviously affected by A3 ＋cat-ions.They exhibit obvious soft eningin the order of Fe3 ＋〉Cr3 ＋〉 Al3 ＋.This is attribu-ted to the size and electronegativity effects of the A3 ＋cation onthe bond strength and flex-ibility of the MO4 tetrahedra.