Transparent ceramics: Processing, materials and applications

Transparent polycrystalline ceramics have found various applications, such as laser hosts, infrared (IR) windows/domes, lamp envelopes and transparent armors, instead of their single crystal counterparts, due mainly to their processing flexibility in fabricating items with large sizes and complex shapes and more importantly cost-effectiveness. High optical transparent ceramics require high purity and high density. To achieve high purity final products, it is necessary to use high purity precursor powders. To get high density, various sintering technologies have been employed, such as high-pressure (HP) sintering, high isostatic pressure (HIP) sintering, vacuum sintering and spark plasma sintering (SPS). At the same time, various wet chemical synthesis routes have been used to produce precursor powders at submicron or even nanometer scales, with significantly improved sinterability. Transparent ceramics for armor and IR window/dome applications should have superior mechanical and thermal properties. Therefore, nanosized ceramics and nanocomposite ceramics have attracted much attention more recently. This review was aimed to summarize the latest progress in processing, materials and applications of transparent ceramics. It is arranged by starting with a brief introduction, followed by a detailed description on various sintering technologies used to develop transparent ceramics. After that, potential applications of transparent ceramics, together with their optical, mechanical and thermal properties, will be discussed. It will be concluded with discussions on future trend and perspectives, as well as some important issues, of transparent ceramic materials.