DSC and single-crystal X-ray structural study on phase transitions in RbNaSO₄

ABSTRACT

As one of the new ABXY₄-type member in the (NH₄)₂SO₄ family, rubidium sodium sulphate (RbNaSO₄) was crystallized by evaporating the aqueous solution at 303 K. The phase transition and crystal structure were studied by means of thermogravimetric analysis, differential scanning calorimetry (DSC) and single-crystal X-ray diffraction. As a result of thermal anomaly detection in the temperature range between 93 K and 773 K, anomalies corresponding to phase transitions were observed at around 693 K and 503 K. It was also revealed that RbNaSO₄ belonged to the monoclinic crystal system at room temperature and had lattice constants of a = 5.9778(5) Å, b = 10.4509 (8) Å and c = 7.8294 (11) Å, γ = 90°.