Density measurement of solid and molten Sb₂Te₃ chalcogenide alloy by sessile drop method

Sb₂Te₃ chalcogenide alloy has been widely investigated due to its applications in phase change random access memory (PCRAM) and thermoelectric materials. The density of Sb₂Te₃ alloy is a key factor for both applications. In this work, the densities of Sb₂Te₃ chalcogenide alloy in solid and molten states have been determined as a function of temperature by the sessile drop method. The density at room temperature was also determined by the Archimedean method to verify the reliability of data obtained by the sessile drop method. The density of solid Sb₂Te₃ alloy decreases linearly with increasing temperature and there is a discontinuous density decrease at the melting temperature due to the phase change. In the molten state, the density continues decreasing with increasing temperature. The molar volume of Sb₂Te₃ chalcogenide alloy increases by about 4% from room temperature to just below the melting temperature and by 6% at the melting temperature from the solid to molten state, which may cause large stress for PCRAM devices.