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In this paper, we report results of thermoanalytical investigation on the reaction between ZrOCl 2 Á8H 2 O and (NH 4 ) 2 HPO 4 in molar ratio 1:2. Differential thermalthermogravimetric and X-ray diffraction analyses were performed in order to reveal the chemical transformations, which took place during heating of the individual compounds ZrOCl 2 Á8H 2 O, (NH 4 ) 2 HPO 4 and the mixture ZrOCl 2 Á8H 2 O:2(NH 4 ) 2 HPO 4 . It was shown that the transformations in the mixture below 160°C were connected with dehydration of ZrOCl 2 Á8H 2 O and interaction between the components of the mixture, which resulted in the formation of NH 4 Cl, NH 4 H 2 PO 4 and a mainly amorphous zirconium phase, most likely t-ZrO 2 . The zirconium component subsequently reacted with ammonium dihydrophosphate (below 200°C) or with dehydrated phosphate derivatives (above 200°C), which in both cases yielded an amorphous product. The interaction between the components of the mixture resulting in the formation of ZrP 2 O 7 was completed by its crystallisation at 610°C. Our study indicates an alternative low-temperature approach for the synthesis of the technologically important ZrP 2 O 7 material.

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