Physicochemical properties of R1-xBaxMnO3 +/-delta (R = rare earth) solid solutions

Nd1-xBaxMnO3 +/- delta (0.1 less than or equal to x less than or equal to 0 .5) and R0.7Ba0.3MnO3 +/- (delta) (R = La, Pr, Sm, Eu) solid solutions were prepared from nitrate mixtures by solid-state reactions in air and were ch aracterized by x-ray diffraction and thermogravimetry. The oxygen content o f the solid solutions was determined by iodometric titration. The materials were found to have a nearly perfect oxygen stoichiometry (delta similar or equal to 0). As shown by pH measurements, the solid solutions have a high water resistance (extent of water degradation no larger than 0. 1 %). The d issociation of the Nd1-xBaxMnO3 +/- delta (0.2 less than or equal to x less than or equal to 0.4) solid solutions was studied as a function of tempera ture and oxygen partial pressure (-10 less than or equal to log(p(O2) /Pa) less than or equal to 1.4) by a special TG technique.