Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original paper

František Laufek, Anna Vymazalová, Marek Tuhý

Ag, Cu, Hg, Pt, Sb and Te substitutions in the synthetic analogue of palladseite, Pd₁₇Se₁₅: an experimental mineralogical study

Journal of Geosciences, volume 66 (2021), issue 4, 205 - 213

DOI: http://doi.org/10.3190/jgeosci.333

The solubility of Ag, Cu, Hg, Pt, Sb and Te in the synthetic analogue of palladseite was experimentally studied at 350 °C. To document the impact of these elements on the palladseite crystal structure, Rietveld refinement analysis of experimental products was performed. The synthetic Pd₁₇Se₁₅ dissolves at 400 °C 3.6, 6.4, 8.8, 9.7, 6.1 wt. % of Cu, Ag, Hg, Pt and Te, respectively. The solubility of Sb in synthetic Pd₁₇Se₁₅ is less than 0.03 wt. %. Three different types of incorporation of the above-mentioned elements to the palladseite structure have been observed. Ag, Cu and Hg occupy a position 3d of the Pm-3m space group, which was empty in the unsubstituted Pd₁₇Se₁₅. Consequently, Pd occupancy of adjacent [Pd(4)Se₆] octahedron is reduced to 0.46 and 0.51 for Cu and Ag-bearing palladseite, respectively. Incorporation of Hg to the palladseite structure causes vacancy of this Pd(4) position. Pt partially substitutes Pd at the Pd(2) position (6f ), forming Pd_0.41/Pt_0.59 mix site showing square-planar coordination by Se atoms. Te atoms substitute for Se. The refined unit-cell parameter increased from the initial value of a = 10.6074(1) Å for Pd₁₇Se₁₅ to 10.6680(1) Å for Te-bearing palladseite. Incorporation of Cu, Ag and Hg to the palladseite causes significant changes of its powder X-ray diffraction pattern and hence can be detected by PXRD.