Hydrothermal synthesis, structural and thermal characterizations of three open-framework gallium phosphites

Three isostructural layered gallium phosphites, A[Ga(HPO3)2] (A = K, NH4, Rb), have been successfully prepared under hydrothermal conditions and their structure solved by single crystal X-ray diffraction. Thermogravimetric analyses carried under air atmosphere indicate that alkali cations containing compounds are stable up to 750 K. AGaP2O7 (with A = K or Rb) is identified as major constituent after thermal treatment. For NH4 phosphite compound, the decomposition leads to an amorphous phase accompanied with orthorhombic GaPO4. These thermal studies evidence the oxidation reaction of phosphite to phosphate anions.306