Experimentally and Theoretically Revealing the Co-Doping Effects of Ce-Sr in Gd 2 Zr 2 O 7 .

To safely dispose radioactive waste (including, e.g., thorium and radiostrontium), Ce 4+ and Sr 2+ were chosen as simulated surrogates of α and β waste and were introduced into the Gd 3+ site in Gd 2 Zr 2 O 7 to maintain the average cationic radius and to compensate for charge. A series of Gd 2- x Sr x /2 Ce x /2 Zr 2 O 7 (0.00 ≤ x ≤ 0.25) compounds were examined by experimental and theoretical calculations to investigate the co-doping effects of α and β waste in a Gd 2 Zr 2 O 7 -based matrix. The effects of Ce 4+ and Sr 2+ content on the phase, unit cell parameters, active modes, mechanical property, and microstructure were studied systematically. Moreover, the limit of incorporation of Ce 4+ and Sr 2+ in Gd 2 Zr 2 O 7 pyrochlore and the lattice parameters were also calculated through virtual crystal approximation theory, and the results were found to well agree with experimental results.