Crystal structure of hafnium palladium gallium, HfPdGa

Abstract

GaHfPd, hexagonal, P 6 2 c (no. 190), a =7.1572(2) Å, c =6.8945(4) Å, V =305.9 Å 3 , Z =6, R gt(F) =0.019, wR ref (F 2 ) =0.031, T =293 K.Source of material A1:1:1 mixtureo ft he elementalc omponents (hafnium pieces, 99.9 %, ChemPur; palladium wire, 99.9 %, ChemPur; gallium pieces, 99.999 %, ChemPur) was arc-meltedinaprotective atmosphere of purified argon. The homogenization was performed in an evacuatedq uartz tube at 800°Cfor two weeks followed by subsequent quenching in cold water. Single crystals which were suitable for structure refinements were obtained by annealing of pre-reacted reguli at temperatures slightly below the melting point (controlled visually) using ahigh frequency furnace [1]. Experimental detailsSample characterization was performed by X-ray powder diffraction (Huber Image Plate Guinier camera G670,Cu K a 1 radiation, l =1.54056 Å,5°£ 2 Q£100°) and optical metallography as well as energy dispersive X-ray spectroscopy (EDXS). The compound was found to be asingle phase. EDXS confirmed the equiatomic composition. Lattice parameters were obtained by aleastsquares refinement of 36 reflections determined from apowder diffraction pattern (LaB 6 as internal standard, a =4 .15692 Å). The refined lattice parameters were used in the last runs of the structure refinement and for calculations of interatomic distances. DiscussionThe new ternary equiatomic compound HfPdGaisisostructural with HfRhSn[2] which represents adistorted and ordered variety of the well-known Fe 2 Pstructure type [3] andits ternary derivative ZrNiAl [4,5]. Aklassengleiche symmetry reduction of index 2(k 2 )from space group P 6 2 m (ZrNiAl) to P 6 2 c (HfPdGa) is accompanied by ad oubling of the lattice parameter c which is causedbyaslight shift of the Hfatoms within the (001)