mixedoxide

Mixed oxide refers to oxide-based materials that contain two or more metal elements within a single oxide system. These materials can exist as single-phase solid solutions, where cations substitute for one another in a common oxide lattice, or as multi-phase systems in which two or more distinct oxide phases coexist. Mixed oxides are studied in ceramics, catalysis, electronics, and nuclear materials for their tunable properties.

In solid solutions, the solubility of different cations depends on ionic radii, valence, and crystal structure compatibility, which in turn affect lattice parameters and defect chemistry. In multi-phase oxides, separate oxide phases maintain their identities, offering combined properties such as enhanced catalytic activity, oxygen storage capacity, or specific optical and magnetic behaviors. The overall performance of mixed oxides is often governed by oxygen stoichiometry and redox chemistry.

Synthesis methods include solid-state reaction, co-precipitation, sol-gel processing, and combustion synthesis, followed by calcination and sintering to produce dense ceramics. Achieving chemical homogeneity and controlling microstructure are important to minimize phase separation and unwanted grain growth.

Applications span several fields. Nuclear energy employs mixed-oxide fuels, such as uranium-plutonium oxide (MOX), to utilize fissile materials efficiently. In catalysis, ceria-zirconia and other mixed-oxide systems serve as oxygen storage and redox-active catalysts. Mixed oxides are also used as pigments, dielectric and electronic materials, and in energy storage and conversion devices.

Challenges include phase stability at high temperatures, defect control, and, for nuclear uses, radiological safety and regulatory considerations.