Oxygen nonstoichiometry and the thermodynamic properties of manganites Ca_(1-x-y)Sr_xLa_yMnO_(3-δ)

摘要

The content of oxygen in Ca_(0.6-y)Sr_(0.4)La yMnO_(3-δ), where y = 0 and 0.05, was determined by coulometric titration over the temperature range 650-950°C at oxygen partial pressure in the gas phase varied from 10~(-4) to 1 atm. The results were used to calculate the partial molar enthalpy, δi/_O(δ), and entropy, δS_O(δ), of oxygen in manganites. Changes in the δH_O(5) and δS_O(δ) dependences caused by the introduction of lanthanum are evidence of the formation of local clusters of the double perovskite type in the Ca_(0.6)Sr _(0.4)MnO_(3-δ) matrix.