Claim: Caesium bisulfate or CsHSO4 consisting of tetrahedral sulfate centers that bridge caesium ions, and goes through three crystalline phases, with the last phase conducted at a room temperature.
Evidence: Caesium bisulfate or cesium hydrogen sulfate is an inorganic compound with the formula CsHSO4. Based on the results of X-ray crystallography, the structure consists of tetrahedral sulfate centers that bridge caesium ions. CsHSO4 goes through three crystalline phases that are referred to as phase III, II, and I. CsHSO4 is initially existing in phase III at a room temperature of 21 °C.