Preparation and microstructural characterization of (Nd1−xGdx)2(Ce1−xZrx)2O7 solid solutions

(Nd1−xGdx)2(Ce1−xZrx)2O7 (0 ≤ x ≤ 1.0) powders with an average particle size of 100 nm were synthesized with chemical-coprecipitation and calcination method, and were characterized by X-ray diffractometry and scanning electron microscopy. The sintering behaviour of (Nd1−xGdx)2(Ce1−xZrx)2O7 powders was studied by pressureless sintering at 1600–1700 °C for 10 h in air. The relative densities of (Nd1−xGdx)2(Ce1−xZrx)2O7 solid solutions increase with increasing the sintering temperature, and gradually decrease with increasing the content of neodymium and cerium at identical temperature levels. (Nd1−xGdx)2(Ce1−xZrx)2O7 solid solutions have a single phase of defect fluorite-type structure among all the composition combinations studied. The lattice parameters of (Nd1−xGdx)2(Ce1−xZrx)2O7 solid solutions agree well with the Vegard's rule.