Material having a controlled microstructure, core-shell macrostructure, and method for its fabrication

Disclosed is a method for making a material having a controlled microstructure, the method including providing particles of a ceramic mineral material, the particles having a metal oxide dopant therein. The particles of the ceramic mineral material are consolidated into larger aggregates of a size relevant to the desired application using standard industrial mixing and pelletizing technology. The aggregates are heated under reducing conditions so that at least part of the dopant is reduced to form a transient, metastable liquid phase among the particles. The liquid phase includes at least part of the reduced dopant and promotes sintering of the particles and forms islands of reduced metal within the material and on the surface of the aggregates. Following heating of the aggregates under reducing conditions, the aggregates are heated under oxidizing conditions such that the islands of reduced metal are oxidized and/or go into solid solution within the particles, thereby creating voids within and form a shell thereon the particles.