NOVELTY - Preparing a homologous phase yttrium- and ytterbium-doped barium-zirconate-cerate (BZCYYb), comprises: (a) obtaining at least the following ingredients in stoichiometric amounts: (i) barium carbonate powder and zirconium oxide powder having average particle diameters in the nanometer range, (ii) cerium oxide powder having average particle diameter in the micrometer range, and (iii) ytterbium oxide powder and yttrium oxide powder; (b) mixing the ingredients from step (a); (c) calcining the resulting mixture; and (d) optionally repeating steps (b) and (c) to obtain a homologous phase BZCYYb.    USE - The method is useful for preparing a homologous phase BZCYYb, where the BZCYYb is used as an electrolyte or an electrode (all claimed).    ADVANTAGE - The method prepares improved electrolyte and electrode materials to be used in SOFCs, and optimizes the preparation of materials to be used in SOFCs that have both high purity and electrical conductivity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a BZCYYb electrolyte material produced by the method above;    (2) a solid oxide fuel cell comprising an electrolyte comprising the BZCYYb; and/or one or more of an anode, an electrolyte and a cathode comprising the BZCYYb;    (3) a method for preparing single phase BZCYYb, comprising: (a) mixing the ingredients (i), (ii), and (iii) together with a solvent to form a mixture; (i) barium carbonate powder and zirconium oxide powder having particle diameters in the 50-200 nanometer range, (ii) cerium oxide powder having particle diameter in the 1-20 micrometer range, and (iii) ytterbium oxide powder and yttrium oxide powder; (b) evaporating the solvent from the mixture; (c) calcining the mixture; and (d) optionally grinding and re-calcining the mixture to obtain a single phase BZCYYb;    (4) an improved method of making a BZCYYb by mixing and calcining the ingredients, where the improvement comprises using nanometer sized zirconium oxide powder and micrometer cerium oxide powder as starting ingredients;    (5) a BZCYYb material made by the latter method; and    (6) a solid oxide fuel cell (SOFC) comprising an anode adjacent and electrolyte adjacent a cathode, where one or more of the anode, electrolyte and cathode are made with the latter method.