TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation: No preparation method is given. Preferred Components: In (I): the M1 and M2 are present at atomic ratio of x:1-x; and the M1 and manganese are present at atomic ratio of 1:y. (I), (II) and (III) have an average temperature of maximum oxygen absorption upon heating and cooling T(maxA) of at most 400 degrees C, preferably at most 250 degrees C and a temperature of maximum oxygen desorption T(maxD) of at most 400 degrees C, preferably at most 300 degrees C. In (III) the at least one element is yttrium, holmium or dysprosium or yttrium and a member comprising lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium or dysprosium (preferred). The formal oxidation state of manganese is preferably 3.3-3.8. The carbon-containing fuel is coal or natural gas.x = 0.1-1, preferably 0.3-1; andy = 0 to less than or equal to 10.Preferred Process: In the process of preparing oxygen, the step of separating is carried out at at most 400 degrees C, preferably at most 250 degrees C. The process is thermal swing absorption or ceramic autothermal recovery. Preferred Method: The method of generating electricity, further comprises capturing and storing carbon dioxide produced by the burning.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: In the oxygen conducting membrane, the support material decomposes when exposed to air at 500 degrees C or has a glass transition temperature or a melting point of at most 500 degrees C. The support material comprises: at least one member comprising an organic polymer, a silicone rubber or glass; and at least one member comprising graphite, carbon black, aluminum, copper, iron, nickel, steel, zinc, tin, lead or their alloys. The support material is electrically conductive, and forms a contiguous structure exposed on both the first and second opposing surfaces. Preferred Definitions:    z = 3.15-3.4;    M1 = Y or Ho;    M2 = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb or Dy (where M1 is Y);    z2 = at least 3.2; and    x1 = 0.3-0.9.    EXAMPLE - Dysprosium trioxide, yttrium trioxide and manganese dioxide were thoroughly mixed in an agate mortar, and fired in air at 800-1300 degrees c with intermediate grindings followed by pressing samples into high-density pellets at 1kbar to give dysprosium yttrium manganese oxide (Dy1-xYxMn(3+ delta ), where x is 0, 0.1. 0.3, 0.5 or 0.7), which was then fired under ultra-high-purity argon (99.999%) at 1300 and 1400 degrees C, and (Dy1-xYxMn(3+ delta ), where x is 0 and 0.1) was then subsequently fired under ultra-high-purity argon with a hydroxy purifier (oxygen partial pressures of 5-10 ppm) at 1400 degrees C.