Structural, IR and thermal study of a new inorganic solid acid: Rb3(HSeO4)2.5(H2PO4)0.5

The infrared spectrum performed at room temperature in the frequency range 4000-500 cm−1 confirms the presence of structural disorder in this material and the coexistence of two different anions (H2PO4− and HSeO4−) in the same crystal structure. The thermogravimetry (TGA) analysis and the differential scanning calorimetric (DSC) show the presence of a structural phase transition of the title compounds at 374 K.