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 less than or equal to x less than or equal to 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 less than or equal to x less than or equal to 0.6 whereas cubic fluorite phase is stable for 1 less than or equal to x less than or equal to 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. (C) 1998 Elsevier Science S.A. All rights reserved