Preparation and Thermal Decomposition of Mixed Oxalates of Zirconium and Copper or Titanium

Abstract

The {ZrO(IV), Cu(II)}- and {ZrO(IV), Ti(IV)}-mixed oxalato compounds were obtained as powders by the homogenous reaction in aqueous solution of ZrOCl₂ with K₂[Cu(OX)₂] or K₂[TiO(OX)₂]. The compositions of these compounds were found to be (ZrO)₅Cu₈(OX)₁₂(OH)₂(H₂O)₂₅ ([Zr-Cu]) and (ZrO)(TiO)₂(OX)₂(OH)₂(H₂O)₇ ([Zr-Ti]), respectively. Both compounds released almost all water molecules at 200°C. In the range of 350 to 450°C, [ZrCu] formed the intermediate which had the composition of (ZrO₂)5(CuO)725010.75(CO₃)_0.75 or (Zr0)_0.75(ZrO₂)4.25(CuO)₈, (CO₃)0.75 and, above 600°C, gave (ZrO₂)₅(CuO)₈ which was merely a mixture of each metal oxide. [Zr-Ti] was found to form an intermediate of (ZrO)_0.8(ZrO₂)0.2(TiO₂)₂(CO3)0.8 or (ZrO₂)(TiO)_0.8(TiO₂)1.2(CO₃)_0.8 in the range of 350 to 550 °C. This intermediate contained a small amount of CO₂. Further heating to 650°C gave the mixed oxide, (ZrO₂)(TiO₂)₂, the structure of which was similar to that of the orthorhombic ZrTiO₄.