Germanium‐Modified Cordierite Ceramics with Low Thermal Expansion

Magnesium cordierite ceramics modified by ionic substitution of Ge for Si were synthesized, fabricated, and characterized. The effect of the amount of ionic substitution on thermal expansion was investigated. Ionic substitution of ∼20% germanium for silicon reduces thermal expansion to zero at room temperature. A processing schedule to achieve nearly theoretical densities in germanium cordierite specimens was developed, and the microstructures of sintered samples were examined by scanning electron microscopy. Other thermal properties such as specific heat and thermal conductivity were also measured for the germanium‐modified cordierites.