Preparation and thermal decomposition of mixed oxalates of zirconium and copper or titanium.

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.