First principles study on stability of base and precious metals pentlandite-like compounds

• Published in: Theoretical chemistry accounts Vol. 142; no. 1
• Main Authors: Molala, Kgwajana B., Mkhonto, Peace P., Mehlape, Mofuti A., Ngoepe, Phuti E.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2023; Springer Nature B.V
• Subjects: Atomic/Molecular Structure and Spectra; Binary systems; Chemistry; Chemistry and Materials Science; First principles; Heat of formation; Inorganic Chemistry; Iridium; Metal sulfides; Nickel ores; Noble metals; Organic Chemistry; Osmium; Palladium; Pentlandite; Phase stability; Physical Chemistry; Platinum; Ruthenium; Ternary systems; Theoretical and Computational Chemistry; PGEs; Pentlandite-like; Density of states; DFT; Stability
• ISSN: 1432-881X; 1432-2234
• DOI: 10.1007/s00214-022-02951-0

First principles method was used to investigate the phase stability of the platinum group elements (PGEs) precious metal sulphides, M 9 S 8 (M = Ru, Pd, Os, Ir, Rh, Pt), (Ru,Pd) 9 S 8 and (Os,Pt) 9 S 8 , in pentlandite-like structure from thermodynamic, electronic, mechanical and vibrational stability conditions. The heats of formation of binary systems predicted a decreasing stability: Os 9 S 8  > Ru 9 S 8  > Ir 9 S 8  > Rh 9 S 8  > Pt 9 S 8  > Pd 9 S 8 . For the ternary systems, the stability decreased in the order: Os 5 Pt 4 S 8  > Os 4 Pt 5 S 8  > Ru 5 Pd 4 S 8  > Ru 4 Pd 5 S 8 . The average number of electrons per atom ( e/a ) = 7.58, depicted stability for Rh 9 S 8 , Ir 9 S 8 , (Ru,Pd) 9 S 8 and (Os,Pt) 9 S 8 . The Rh 9 S 8 , Ir 9 S 8 , Pd 9 S 8 and Os 9 S 8 were mechanically and vibrational stable, whereas Pt 9 S 8 and Ru 9 S 8 were unstable. All ternary systems were mechanically stable except for Ru 4 Pd 5 S 8 due to C11 < C12. These findings established a possible existence of PGEs metal sulphides in a pentlandite-like structure and predicted new precious metal sulphides.