Thermal decomposition of CuCrO4·2CuO·2H2O and phase relations in the Cu-Cr-O system
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The compound, CuCrO4·2CuO·2H2O has been synthesized by precipitating it from the aqueous solution containing chromium (VI) oxide and basic copper (II) carbonate. Thermal decomposition of CuCrO4·2CuO·2H2O has been studied by thermogravimetry and differential scanning calorimetry in flowing air and pure oxygen between 298 and 1373 K. The formation of different phases after each stage of decomposition were identified by X-ray diffraction analysis. The compound CuCrO4 was found to be non-stoichiometric. Based on the results obtained in this study and those reported earlier, the isothermal section of the phase diagram of the Cu-Cr-O ternary system has been composed at 600 and 1150 K. Scanning electron microscopy studies of CuCrO4·2CuO·2H2O precipitate showed rectangular plate-like morphology. The decomposition of CuCrO4·2CuO·2H2O at 798 K in air resulted in the formation of a mixture of fine powder of CuCr2O4+CuO (Adkin's catalyst) having a uniform spherical geometry and a particle size less than 0.1 Μm.
Keywords2H2O Chromium Phase Diagram Differential Scanning Calorimetry Calorimetry
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