Structure and oxygen stoichiometry of phases in La–Pr–O system

Citrate gel method has been employed to produce homogeneous mixed rare-earth oxides in La2−xPrxO3+y (0≤x≤2) system. The phases obtained at 1473 K in static air have been characterised for the entire range of compositions for their crystal structure. Hexagonal structure is stable for 0≤x≤0.6 whereas cubic fluorite phase is stable for 1≤x≤2. The unit cell parameters are reported for the range of single phase compositions. Wet-chemical analysis reveals that the compositions adopting hexagonal structure are stoichiometric (y=0) whereas the compositions crystallising in the fluorite structure have the y increasing from 0.33 to 0.66 as x is varied from 1 to 2.