"114"型氧化物SrAZn_(2)GaAlO_(7)(A=Ba^(2+),Sr^(2+))的晶体结构研究

Crystal structures of "114"-type oxides SrAZn_(2)GaAlO_(7)(A=Ba^(2+),Sr^(2+))

"114"型氧化物由于其独特的晶体结构与有趣的物理性质而受到了人们的广泛关注.为研究"114"化合物中A位离子的大小对结构对称性及原子占位的影响,设计合成了两个A位离子大小不同的"114"型新化合物SrAZn_(2)GaAlO_(7)(A=Ba^(2+),Sr^(2+)).粉末X射线衍射(powder X-ray diffraction,PXRD)分析结果表明,随着A位离子半径的减小,SrAZn_(2)GaAlO_(7)的结构对称性由P31c(A=Ba^(2+))降低到Pna2_(1)(A=Sr^(2+)).基于PXRD数据的Rietveld精修结果表明,SrAZn_(2)GaAlO_(7)中离子半径较小的Al3+倾向于占据三角层中的四面体间隙,而较大的Zn^(2+)/Ga^(3+)则倾向于占据Kagomé层中的四面体间隙.

The“114”-type oxides have gained extensive attention due to their unique crystal structures and intriguing physical properties.In this paper,two new“114”-type oxides,SrAZn_(2)GaAlO_(7)(A=Ba^(2+),Sr^(2+)),were designed and synthesized to investigate the influence of A-site cationic size on structural symmetry and atomic occupations.Powder X-ray diffraction(PXRD)results indicated that the structural symmetry of SrAZn_(2)GaAlO_(7)(A=Ba^(2+),Sr^(2+))descended from P31c(A=Ba^(2+))to Pna2_(1)upon decreasing the ionic radius of the A-site cations.Rietveld refinements of PXRD data revealed that Al3+ions with a smaller ionic radius prefered to occupy the tetrahedral cavities within the triangular layer while the larger Zn^(2+)/Ga^(3+)ions in favour of the tetrahedral cavities within the Kagomélayer.