Addition of (A) Blocking Agent(s) in a Ceramic Membrane for Blocking Crystalline Growth of Grains During Atmospheric Sintering

A method of preparing a composite, comprising the step of sintering a powder blend while controlling an oxygen partial pressure (pO2) of a gaseous atmosphere surrounding the powder blend, wherein:

• the powder blend comprises a mixed electronic/oxygen O2− anionic conducting compound (C1) and a compound (C2) chosen from MgO and BaTiO3;
• the resultant composite comprises at least 75 vol % of compound (C1), from 0.01 to 25 vol % of compound (C2), and from 0 vol % to 2.5 vol % of compound (C3), compound (C3) produced from at least one chemical reaction represented by the equation:
• xFC1+yFC2→zFC3,
• in which equation FC1, FC2 and FC3 represent the respective crude formulae of compounds (C1), (C2) and (C3) and x, y and z represent rational numbers greater than or equal to 0;
• compound (C1) is chosen from perovskite oxides of formula (II):
• [Ma1−x−uMa′xMa″u][Mb1−y−vMb′yMb″v]O3−w (II)
• wherein:
• Ma represents an atom chosen from scandium, yttrium, or from the families of lanthanides, actinides or alkaline-earth metals;
• Ma′, which is different from Ma, represents an atom chosen from scandium, yttrium or from the families of lanthanides, actinides or alkaline-earth metals;
• Ma″, which is different from Ma and Ma′, represents an atom chosen from aluminum (Al), gallium (Ga), indium (In), thallium (Tl) or from the family of alkaline-earth metals;
• Mb represents an atom chosen from transition metals;
• Mb′, which is different from Mb, represents an atom chosen from transition metals, aluminum (Al), indium (In), gallium (Ga), germanium (Ge), antimony (Sb), bismuth (Bi), tin (Sn), lead (Pb) and titanium (Ti);
• Mb″, which is different from Mb and Mb′, represents an atom chosen from transition metals, alkaline-earth metals, aluminum (Al), indium (In), gallium (Ga), germanium (Ge), antimony (Sb), bismuth (Bi), tin (Sn), lead (Pb) and titanium (Ti);
• 0<x≦0.5;
• 0≦u≦0.5;
• (x+u)≦0.5;
• 0≦y≦0.9;
• 0≦v≦0.9;
• 0≦(y+v)≦0.9;
• and
• w is such that the structure in question is electrically neutral.