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°.