Coprecipitation synthesis and sintering property of (Yb_xSm _1-x)₂Zr₂O₇ ceramic powders

(Yb_xSm_1-x)₂Zr₂O₇ (Ln=5lanthanide) ceramic powders were synthesised with chemical coprecipitation and calcination method. Thermal decomposition behaviour of precipitates was studied by differential scanning calorimetry-thermogravimetry. The powders were characterised by X-ray diffractometry, scanning electron microscopy and transmission electron microscopy with energy dispersive spectroscopy. The synthesised powders have a particle size of about 100 nm, and exhibit to a certain extent agglomeration. The sintering behaviour of (Yb_xSm _1-x)₂Zr₂O₇ powders was studied by pressureless sintering method at 1550-1700°C for 10 h in air. The relative densities of (Yb_xSm_1-x)₂Zr₂O ₇ ceramics increase with increasing sintering temperature, and reach above 95% when sintered at 1700°C for 10 h in air. Sm₂Zr ₂O₇ and Yb_0·1Sm_0·9) ₂Zr₂O₇ ceramics have a pyrochlore structure; however, (Yb_xSm_1-x)₂Zr₂O₇ (0.3≤x≤1.0) ceramics exhibit a defective fluorite type structure.