Unveiling Local Structures and Correlations in Rare-Earth Zirconates

Rare-earth A2Zr2O7 zirconates have traditionally been classified as either long-range ordered pyrochlore structures or disordered defect-fluorite structures. However, recent studies indicate that the so-called defect-fluorite phase exhibits a lower symmetry local structure. Our recent neutron pair-distribution function (nPDF) analysis suggests a continuous structural evolution across the series, with local symmetry resembling the rhombohedral structure of the Lu2Zr2O7 end-member (Fig. 1). The proposed experiment aims to investigate the evolution of the local crystal structure in two solid-solution series, capturing structural transitions from the ordered pyrochlore phase (Er2Ti2O7, Lu2Ti2O7) through the defect-fluorite region (Er2Zr2O7) to the rhombohedral structure of Lu2Zr2O7.

稀土A₂Zr₂O₇型锆酸盐传统上被归类为长程有序烧绿石结构或无序缺陷萤石结构。然而近期研究表明，所谓的缺陷萤石相实则具备更低对称性的局域结构。我们近期开展的中子对分布函数（neutron pair-distribution function，nPDF）分析显示，该系列材料存在连续的结构演变过程，其局域对称性与Lu₂Zr₂O₇端元的菱面体结构（图1）相似。本拟开展的实验旨在探究两种固溶体系列的局域晶体结构演变，完整捕捉从有序烧绿石相（Er₂Ti₂O₇、Lu₂Ti₂O₇）经缺陷萤石相区（Er₂Zr₂O₇）直至Lu₂Zr₂O₇菱面体结构的结构转变过程。