Ab Initio Thermodynamics Study for Phase Separation of Ce_0.75Zr_0.25O₂ Solid Solution

Since CeO₂ shows high oxygen storage/release capacity and this capacity can be further improved by adding ZrO₂, Ce_0.75Zr_0.25O₂ (CZO) has been studied for catalyst support of vehicles’ catalytic converter and fuel electrode of solid oxide fuel cells. Phase separation, however, of CZO under reducing atmosphere at elevated temperatures has been observed experimentally. TEM with EDS shows oxygen-poor and pyro-like phases as intermediates before being completely separated to almost pure CeO₂ and ZrO₂; CeO₂ and ZrO₂ contain less than 1 % Zr and Ce, respectively. Ab-initio thermodynamics with density functional theory is employed to analyse the phase separation behavior of CZO.