Synthesis, characterization and lattice thermal expansion of some compounds in the system Gd 2Ce xZr 2−xO 7

Abstract

Synthesis, characterization and lattice thermal expansion studies of compounds formed in the Gd 2O 3–CeO 2–ZrO 2 system with general stoichiometry Gd 2Ce x Zr 2− x O 7 is being reported. The products obtained were characterized by powder XRD for phase purity and the unit cell parameters determination. It was observed that only 5 mol% of Ce 4+ is soluble in the lattice of Gd 2Zr 2O 7. Further addition of Ce 4+ leads to the formation of fluorite-type phase over a wide range of compositions, i.e. from Gd 2Ce 0.2Zr 1.8O 7 to Gd 2Ce 1.7Zr 0.3O 7. The further extreme Ce 4+ rich compositions show the formation of C-type cubic phase. The lattice thermal expansion studies for the end members of the series and Gd 2Ce 0.1Zr 1.9O 7 were carried out by HT-XRD in the temperature range 20–1200 °C. The coefficients of lattice thermal expansion are 11.6(5) × 10 −6 C −1 for Gd 2Zr 2O 7, 11.4(5) × 10 −6 C −1 for Gd 2Ce 0.1Zr 1.9O 7 and 13.8(5) × 10 −6 C −1 for Gd 2Ce 2O 7.