Ceramic materials for gas separation and oxygen storage

A method of preparing oxygen, comprising separating oxygen from a mixture of gases containing the oxygen, by conducting the oxygen through a manganese oxide, or absorbing and releasing the oxygen from the manganese oxide,

• wherein the manganese oxide comprises M1, M2, Mn and O, and
• wherein:
• M1 is selected from the group consisting of In, Sc, Y, Dy, Ho, Er, Tm, Yb and Lu,
• M2 is different from M1, and M2 is selected from the group consisting of Bi, In, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,
• M1 and M2 are present in an atomic ratio of x:1−x, and x =0.1 to 0.9,
• Mn and O are present in an atomic ratio of 1:z, and z >3, and
• the separating is carried out at a temperature of at most 400° C.

A method of preparing oxygen, comprising:

• separating oxygen from a mixture of gases containing the oxygen, by conducting the oxygen through an oxygen conducting membrane,
• wherein the oxygen conducting membrane comprises
• (1) a rare earth manganese oxide, and
• (2) a support material,
• the membrane has first and second opposing surfaces,
• the membrane is not permeable to nitrogen gas,
• the rare earth manganese oxide forms a contiguous structure exposed on both the first and second opposing surfaces, and
• the rare earth manganese oxide has an average temperature of maximum oxygen absorption upon heating and cooling, TmaxA, of at most 400° C., and a temperature of maximum oxygen desorption, TmaxD, of at most 400° C.