Abstract: Provided are methods to fabricate bulk quantities at relatively low-cost of isotropic homogeneous nanostructured materials with high interfacial area whose properties are controlled and optimized by tailored interfaces between discrete dissimilar materials. In a preferred embodiment, the material is formed by uniformly and intimately mixing nanoparticles of different composition and then compacting and consolidating them to near theoretical density by a process that minimizes grain growth and controls the structure of the interfacial film-like region. One preferred application of these materials is a fast ion conducting material that can be used as a solid electrolyte in gas electrolyzers, electrochemical pumps, gas sensors, catalytic reactors, and most importantly in fuel cells.