Abstract
Dielectric ceramic materials have been studied for decades due to both their application in important technologies and the fundamentally interesting relationships among their crystal chemistry, crystal structures, and physical properties. Recent dramatic changes in microelectronics and in particular wireless communications technologies have made the importance of materials with the unusual combination of high dielectric constant, low dielectric loss and low temperature dependence of dielectric constant of great interest. In this review, the present state of knowledge of the chemistry, structure, and dielectric properties of these materials, as well as examples of our own work, are described.