Thermal decomposition of lead zirconyl oxalate hexahydrate

Thermal decomposition of $PbZrO(C_2O_4)_2.6H_2O$ was studied by DTA, thermogravimetry, x-ray diffraction, IR spectroscopy and chemical and gas analyses. The decomposition proceeds through 3 major steps: (i) dehydration; (ii) decomposition of the oxalate to an intermediate carbonate; and (iii) decomposition of the carbonate to $PbZrO_3$. The stoichiometry of the intermediate carbonate and the nature of the end products depend strongly on the surrounding atmosphere. In oxidizing atmosphere like air or O the carbonate has the formula $Pb_2Zr_2O_5CO_3$ and decomposition further to $PbZrO_3$. In nonoxidizing atmosphere or in vacuum a nonstoichiometric $Pb_{2-x}Zr_2O_{5-x}CO_3$ is formed that further decomposition to a mixture of $PbZrO_3$ and $ZrO_2$