The Crystal Structure of CaPd3O4

This paper describes experiments to determine the crystal structure of a new oxide of calcium and palladium, CaPd
3
O
4
. This compound was obtained during the course of efforts to prepare alkaline earth palladates. In this process excess CaCO
3
was heated with PdO in air to about 800° to 900°C. At intervals the reaction mixture was removed from the furnace, thoroughly remixed and then reheated. After several cycles, the reaction products were txamined by x-ray powder diffraction methods and were found to contain CaO, CaCO
3
, small amounts of Pd and PdO plus one or more unidentified phases. The CaO and CaCO
3
were readily removed by washing with aqueous NH
4
CI solution. Small amounts of Pd and PdO remaining in the mixture were removed by boiling with aqua regia, which appeared to have no significant effect on the unknown phase or phases.