Abstract

Germanium-cordierites are derived from the Mg-cordierite ceramic by partially replacing silica in the hexagonal structure with germania. A family of fully crystalline ceramics is thus obtained whose stoichiometry is given as: 2MgO • 2Al₂O₃ • (5-X) SiO₂ • (X)GeO₂. This ionic substitution lowers the coefficient of thermal expansion (CTE) of the material to zero or a near-zero value over a selected temperature range and also eliminates the associated anisotropy. Moreover, this temperature range for zero CTE can be "tailored" to suit the desired applications, a key advantage of Ge-cordierites.

© 1987 Optical Society of America