A graphite tube electric furnace capable of fast heating and cooling, and its use in measuring electrical properties of magnesium oxide single crystal

Abstract

A graphite tube electric furnace has been designed to facilitate measurement of electrical properties of small refractory samples at high temperatures. Conductivity data are obtained with the sample at a uniform temperature in the central zone of the furnace. Thermal EMF data are obtained with the sample in a controlled and measurable temperature gradient at either end of the zone. The furnace tube is mounted axially in a water-cooled cylindrical chamber filled with argon or nitrogen at atmospheric pressure. A novel feature is that, with no thermal insulation other than an annular space round the furnace tube, fast rates of heating/cooling are possible, and thermal equilibrium can be achieved rapidly (in 3 min) at any desired sample temperature up to 3000 degrees C.