Thermal expansion in solid solution Er2−xSmxW3O12

The crystal structural and thermal expansion properties of solid solution Er2−xSmxW3O12 (0 ≦ x ≦ 2.0) have been investigated by X-ray powder diffraction. The XRD patterns indicate that pure phases can form in the composition range of 0.0 ≦ x ≦ 0.5 with orthorhombic structure and 0.6 ≦ x ≦ 2.0 with monoclinic one. The cell parameters and unit cell volumes increase almost linearly with increasing Sm content. Investigations on the thermal properties show that compounds with 0.0 ≦ x ≦ 0.5 exhibit negative thermal expansion in the 200-800 °C temperature range and samples with 0.6 ≦ x ≦ 2.0 possess normal thermal expansion (25-800 °C). It is also found that high samarium content leads to more negative thermal expansion coefficient of Er2−xSmxW3O12 (0.0 ≦ x ≦ 0.5).