Shandites and Parkerites: Variations and Structural relation
The minerals Ni3Pb2S2 and Ni3Bi2S2 are the two archetypes of a family of ternary
compounds with the general formula T3M2X2 (T = Ni, Co, Rh, Pd or Pt; M = In, Sn, Pb, Tl or
Bi; and X = S, Se or Te as shown in table 1.1). The former is known as shandite (in honour of
Professor S. J. Shand,1882-1957)95 while the later was named parkerite by Scholtz in 193694.
Only when M = Bi, ternary compounds T3M2X2 crystallize in the parkerite structure, otherwise shandite structure occurs. Ni3Pb2S2 crystallizes in the trigonal space group R3m where the Ni atoms occupy 9d Wyckoff sites, S atoms at 6c positions and Pb atoms are split between two positions: Pb(1) in 3a and Pb(2) in 3b.
Despite having the same stoichiometry as the mineral shandite, Ni3Bi2S2 crystallizes in a different structure but still related. The parkerite Ni3Bi2S2 crystallizes in the monoclinic structure of the space group C2/m, in which Ni atoms occupy three crystallographic independent positions corresponding to the Wyckoff sites 4g, 4e and 4i. Bi and S atoms occupy two 4i and one 8j positions, respectively.
To continue reading click on the following link:
https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/218014/2/dkogk04255.pdf
Novel magnetic and electronic properties of kagomé-lattice cobalt-shandites( Dissertation_全文 )
Only when M = Bi, ternary compounds T3M2X2 crystallize in the parkerite structure, otherwise shandite structure occurs. Ni3Pb2S2 crystallizes in the trigonal space group R3m where the Ni atoms occupy 9d Wyckoff sites, S atoms at 6c positions and Pb atoms are split between two positions: Pb(1) in 3a and Pb(2) in 3b.
Despite having the same stoichiometry as the mineral shandite, Ni3Bi2S2 crystallizes in a different structure but still related. The parkerite Ni3Bi2S2 crystallizes in the monoclinic structure of the space group C2/m, in which Ni atoms occupy three crystallographic independent positions corresponding to the Wyckoff sites 4g, 4e and 4i. Bi and S atoms occupy two 4i and one 8j positions, respectively.
To continue reading click on the following link:
https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/218014/2/dkogk04255.pdf
Novel magnetic and electronic properties of kagomé-lattice cobalt-shandites( Dissertation_全文 )
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