A high-temperature drop calorimeter for studying substances and materials in the solid and liquid states

The design of an automated isothermal drop calorimeter, which is intended for specific-heat and enthalpy measurements and studying phase transformations in solid and liquid materials in a wide temperature range from room temperature to 2300 K, is described. The distinctive features of the unit consists in the location of the temperature sensor directly in a sample, the use of a mechanical lock for the dropping and lower opening screens of the ampoule, as well as a special gateway. The above factors provide the possibility to carry out measurements at an arbitrary initial temperature of the calorimeter unit and considerably increase the efficiency of the calorimeter. To determine its efficiency, measurements of sapphire enthalpy were performed at temperatures of 575–1275 K. The measurement results differ from the reference data of the National Institute of Standards and Technologies (United States) by 0.05%.