Zr1−xLnxW2O8−x/2 (Ln=Eu, Er, Yb): Solid solutions of negative thermal expansion-synthesis, characterization and limited solid solubility

Zr1−xLnxW2O8−x/2 solid solutions (Ln=Eu, Er, Yb) of different substitution fractions x have been synthesized. Their X-ray diffraction (XRD) patterns have been indexed and lattice parameters calculated based on the α-ZrW2O8 structure. The coefficients of thermal expansion (CTEs) of these solid solutions were estimated to be −10.3×10−6 K−1 in temperature range of 30–100 °C. The solubility of lanthanide ions in these solid solutions decreases linearly with the increase in the radius of substituted lanthanide ions. Based on the concentration dependence of phase transition temperatures, a novel method for determination of solubility of the lanthanide ions in Zr1−xLnxW2O8−x/2 solid solutions has been developed. This method seems to be more sensitive as compared with that based on XRD technique.

The graphic displays the lattice parameters of saturated solid solutions and solubility of Zr1−xLnxW2O8−y as a function of the radius of substituted Ln3+ ions. A more sensitive method is developed to measure the low solubility of the solid solutions. This correlation demonstrates the increase in limited solid solubility follows the lanthanide contraction trend in a way that is opposite to that observed for lattice parameters.Figure optionsDownload as PowerPoint slide