Crystal structures and thermal expansion of Yb2Si2O7–Gd2Si2O7 solid solutions

Abstract

Solid solutions within the Yb2Si2O7–Gd2Si2O7 system were synthesized by a solid state reaction route and characterized for their structural and thermal properties. Incorporation of Gd2Si2O7 into Yb2Si2O7 resulted in multiple phase transformations, with the solid solutions exhibiting the monoclinic β-RE2Si2O7, monoclinic γ-RE2Si2O7, and orthorhombic δ-RE2Si2O7 crystal structures. The stability of crystal structures with additions of Gd2Si2O7 are attributed to space filling and minimization of molar volume. The thermal expansion coefficients (CTE) of the β and γ structures were largely unchanged by the addition of Gd2Si2O7 to the lattice, although the orthorhombic Yb2Si2O7–Gd2Si2O7 solid solution exhibited slightly less anisotropy in CTE of the lattice directions (25°C–1500°C) than undoped orthorhombic δ-Gd2Si2O7.