Crystal structures and hydrogenation properties of palladium-rich compounds with elements from groups 12–16

Abstract

Abstract We report on crystal structure data and hydrogenation properties of 24 palladium-rich intermetallic compounds with elements from groups 12–16 of the Periodic Table. Refined crystal structures based on X-ray powder diffraction data are presented for Pd3As (Fe3P type structure) and several members of the Pd5TlAs type structure family. Hydrogenation was studied in situ by differential scanning calorimetry (DSC) under 5.0 MPa hydrogen pressure up to 430 °C. Pd0.75Zn0.25, PdCd, PdHg, Pd2Sn, Pd5Pb3, Pd13Pb9, Pd3As, Pd20Sb7, Pd8Sb3, Pd5Sb2, PdSb, Pd5Bi2, Pd17Se15, Pd4Se, Pd5TlAs, Pd5CdSe, Pd5CdAs, Pd5HgSe, Pd5InAs, Pd8In2Se and Pd3Bi2Se2 do not show any sign of hydrogen uptake according to DSC and X-ray diffraction. For Pd3Sn and Pd3Pb a significant hydrogen uptake with unit cell volume increases of 0.4 and 0.6 %, respectively, with a retained structure type of the parent intermetallic was observed. Hydrogenation of Pd5InSe yields Pd3InH≈0.9 and a mixture of palladium selenides. Thermal analysis experiments in helium and in hydrogen atmosphere show that this is a multistep reaction with a decomposition of Pd5InSe to Pd3In and a liquid phase and subsequent hydrogenation of Pd3In.