Characterization and phase stability of pyrochlore (Nd1−xCex)2Zr2O7+y (x = 0-1)

Powders of (Nd1−xCex)2Zr2O7+y (x = 0-1) with pyrochlore structure were prepared by sol-spray pyrolysis and subsequent graphite reduction at 1200 °C. The effects of cerium content on crystal structure, phase stability and microstructure of the (Nd1−xCex)2Zr2O7+y (x = 0-1) inert matrix materials were studied. XRD and Raman results presented that all samples were in a single pyrochlore phase. XPS results indicated the cerium was in a single oxidation state of +4. After sintering at 1500 °C for 24 h in air, the sample of x = 1 underwent a phase segregation to Zr1−xCexO2 solid solutions of tetragonal, metastable tetragonal and cubic phases, the sample of x = 0.9 contained a few tetragonal phase in addition to fluorite phase, the samples of x = 0.5-0.8 had a single phase fluorite structure, the samples of x = 0-0.4 maintained the pyrochlore structure.