Coprecipitation synthesis and sintering property of (Yb _x Sm _1-x ) ₂ Zr ₂ O ₇ ceramic powders

(YbxSm1-x)2Zr2O7 (0<x<1·0) 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 (YbxSm1-x)2Zr2O7 powders was studied by pressureless sintering method at 1550-1700°C for 10 h in air. The relative densities of (YbxSm1-x)2Zr2O7 ceramics increase with increasing sintering temperature, and reach above 95% when sintered at 1700°C for 10 h in air. Sm2Zr2O7 and (Yb0·1Sm0·9)2Zr2O7 ceramics have a pyrochlore structure; however, (YbxSm1-x)2Zr2O7 (0·3<x<1·0) ceramics exhibit a defective fluorite type structure.