Effective Thermal-Conductivity Measurement on Germanate Glass–Ceramics Employing the $3\omega$ Method at High Temperature

Abstract

It can be noted that the germanate glass–ceramic is a functional material with excellent thermal stability which can be used in optical devices. The temperature-dependent effective thermal conductivities of CaO–BaO–CoO–Al$_{2}$O$_{3}$–SiO$_{2}$–GeO$_{2}$ glass–ceramics from 295.5 K to 780 K are determined using a $3\omega$ method. One of the main advantages for the $3\omega$ method is to diminish radiation errors effectively when the temperature is as high as 1000 K. Thermal conductivities of CaO–BaO–CoO–Al$_{2}$O$_{3}$–SiO$_{2}$–GeO$_{2}$ increase with a rise in temperature. Effective thermal conductivities of a sample increase from $1.55~\hbox {W}\cdot \hbox {m}^{-1}\cdot \hbox {K}^{-1}$ at 295.5 K to $7.64~\hbox {W}\cdot \,\hbox {m}^{-1}\cdot \hbox {K}^{-1}$ at 698.1 K. The effective thermal conductivity of CaO–BaO–CoO–Al$_{2}$O$_{3}$–SiO$_{2}$–GeO$_{2}$ glass–ceramic increases with a rise of temperature. This investigation can be used as a basis for the measurement of thermal properties of ceramic materials at higher temperature.