Oxide materials are the most common natural materials and are used in various technical and biomedical applications. Oxides are involved in industry to produce energy, various sensors, catalysts and electronic devices. They also find uses in medical applications, personal and home care products, and construction in manufacturing sealants, adhesives, paints and coating. The application of oxide materials will continue to grow in the future and their use as nanostructured materials will open new horizons.This book presents the fundamentals of oxide powders, undoped or doped with metal ions (having spinel, perovskite or crednerite type structure) and obtained by different methods, establishing a connection between the structure and their electromagnetic properties, with the purpose to be used in technological and biomedical applications.