Points of melting-crystallisation and polymorphic transformations of sulfur in density-temperature coordinates

Experiments were carried out in situ and with automatic analogue signal registration during the continuous heating or cooling processes of sulfur samples in the temperature range 20- 350 degrees C with detailed investigation of the melting and crystallisation intervals. The transformation temperatures were measured, and the expansion coefficients, specific volumes, and density of sulfur with different purity grades were calculated. The investigation was carried out with the application of a narrow gamma-radiation beam passing through the sample. Hysteresis of heating and cooling processes as well as the dependence of temperature and volumetric characteristics of melting and solidification on the purity of sulfur samples were discovered. The peculiarities of the processes in connection with sulfur crystallisation and melting are discussed.