THE SYSTEM Hg-Pd-Se AT 400  C: PHASE RELATIONS INVOLVING TISCHENDORFITE AND OTHER TERNARY PHASES

Abstract

Phase relations in the Hg-Pd-Se system were studied by the evacuated silica glass tube technique. For kinetic reasons, experiments were performed in the range 350-400 ºC. We present here the 400 ºC condensed isothermal section for the Hg-Pd-Se system, based on literature data and on our experiments. Two ternary phases were known previously: Pd 8 Hg 3 Se 9 , which corresponds to tischendorfite, and Pd 2 HgSe 3 . We report here on a third phase, Pd 5 HgSe. Tischendorfite forms stable assemblages with palladseite (Pd 17 Se 15 ), tiemannite (HgSe), potarite (PdHg), and with the phase Pd 2 HgSe 3 . In turn, Pd 2 HgSe 3 forms stable assemblages with PdSe 2 (orthorhombic), palladseite (Pd 17 Se 15 ), tischendorfite (Pd 8 Hg 3 Se 9 ), and tiemannite (HgSe). The phase Pd 5 HgSe, stable near the Pd-rich corner of the system, forms stable assemblages with metallic Pd, PdHg (potarite), palladseite (Pd 17 Se 15 ), and other Pd-rich binary palladium selenides. Palladseite forms limited solidsolution and dissolves up to 4.15 at.% Hg at 350 ºC. This solid solution forms stable assemblages with Pd 8 Hg 3 Se 9 , PdSe 2 , and HgPd (potarite). There are no joins involving HgSe (tiemannite) and binary Pd selenides.

Powder diffraction study of Pd2HgSe3

“…The unit cell suggested by Drábek et al . (2014) was confirmed. The crystal structure of Pd 2 HgSe 3 was subsequently refined by the Rietveld method for powder X-ray diffraction data using the FullProf programme (Rodriguez-Carvajal, 1990).…”

“…This phase was first synthetized by Drábek et al . (2014) in his systematic investigation of phase relations in the Hg–Pd–Se system. Drábek et al .…”

“…Drábek et al . (2014) described the trigonal symmetry of the Pd 2 HgSe 3 compound and indicated its unit-cell parameters. However, its crystal structure has been hitherto unknown.…”

“…reported a discovery of a Pd 2 HgSe 3 phase in the form of a small inclusion of approximately 20 µm in size from carbonate veins in Hope's Nose, Torquay, Devon, England. This phase was first synthetized by Drábek et al (2014) in his systematic investigation of phase relations in the Hg-Pd-Se system. Drábek et al (2014) described the trigonal symmetry of the Pd 2 HgSe 3 compound and indicated its unit-cell parameters.…”

Relative Abundance of Z2 Topological Order in Exfoliable Two-Dimensional Insulators

“…[16] was performed. Pd 2 HgSe 3 is a crystalline compound that has recently been identified experimentally [44,45] and whose structure is identical to jacutingaite (Pt 2 HgSe 3 ) and is also potentially exfoliable with a very similar binding energy (∼60 meV ·Å −2 , see Tab. I).…”