The Crystal Structure of CaPd ₃ O ₄

Abstract

This paper describes experiments to determine the crystal structure of a new oxide of calcium and palladium, CaPd <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> . This compound was obtained during the course of efforts to prepare alkaline earth palladates. In this process excess CaCO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> 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 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> , small amounts of Pd and PdO plus one or more unidentified phases. The CaO and CaCO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> were readily removed by washing with aqueous NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> 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.