MELTING OF NACL IN A HEATER AS A SIMPLE TEMPERATURE MONITOR AT HIGH-PRESSURE

A simple method to monitor the temperature in a high pressure apparatus has been developed. In this, a small amount of NaCl placed in the graphite heater of a pressurized furnace assembly melted when the heater temperature was increased and this caused an abrupt change in the heater resistance. This effect could be used to measure the sample temperature in a high-pressure experiment and to calibrate the temperature as a function of electric power. The method was used successfully to attain a better control of temperature in growing crystals of cubic boron nitride under high-pressure high-temperature conditions.