Synthetic Mica

Abstract

Synthetic mica surpasses natural mica in stability at elevated temperatures, and it can be produced in extremely high purity and uniformity. Those compounds which are referred to as aynthetic mica are the so-called fluoromicas which, for example, are formed by substitution of F^- for OH^- in the ideal chemical formula for natural phlogopite, KM₃ AlSi₃O₁₀ (OH) ₂. A variety of fluoromicas having various properties can also be synthesized by substituting cations in the fluoromica crystal structure. Therefore, use of fluoromicas developed now field of applications where natural mica could not serve. The growth of large booklet of fluorophlogopite crystals has been achieved with the Stockbarger technique using seed crystals of mica. This method gives large, good quality crystals in good yields. Several ceramics using the small crystals of fluoromicas have been developed. These ceramics are unique because they can be machined to precision tolerances using conventional tools. The present paper are first outlined with the synthesis of mica, isomorphically substituted fluoromicas and the growth of a booklet of fluorophlogopite crystals, and then a few fluoromica ceramics are briefly introduced.