Phase formation and evolution of Cu:Zn partials in binary metal pyrophosphates Cu(2−x)Zn(x)P2O7; x ≈ 1

Binary metal pyrophosphate powders were prepared by the solid state reaction method and subsequently calcined at 400, 500, 600, 700, and 800 °C in order to study Cu:Zn partial evolution to the final CuZnP2O7 product. Synchrotron X-ray absorption, X-ray diffraction, Raman, FT-IR spectroscopy, and thermogravimetric analysis were used in this investigation. Phase evolution of the reaction products was investigated systemically. The results showed that complicated mixtures contributed to the reaction of synthesis temperature. The reaction comprised 3CuO·2P2O5·0.3NH3·0.2H2O, Cu2P2O7, Zn2P2O7, and Zn2P2O7·3H2O intermediates. Decreasing percentage of 3CuO·2P2O5·0.3NH3·0.2H2O intermediates was related directly to an increasing final product. Cu:Zn contents changed in Cu(2−x)Zn(x)P2O7 in the temperature range of 400-600 °C, when x ≈ 1 clearly was related linearly to the reaction temperature. The final product was confirmed by EXAFS fitting spectra as solid solution between the Cu and Zn atom in the CuZnP2O7 structure, and it indicated environment around metal atoms.