The influence of vacuum on polymorphic transformations in rubidium nitrate

Abstract

Structural phase transitions in rubidium nitrate under normal pressure and in a vacuum (under residual pressures of 8 × 10−1, 8 × 10−2, and 8 × 10−3 Torr) were investigated using high-temperature X-ray diffraction. It is found that three transformations occur in RbNO3 crystals in the range between room temperature and the melting point. Only at a pressure of 8 × 10−3 Torr does the temperature range of existence of individual modification narrow and the transformation point shift to higher temperatures.