Parkerite (Ni3Bi2S2) Structure : AB2C_oP8_51_e_be_f

Picture of Structure; Click for Big Picture
Prototype : Bi2Ni3S2
AFLOW prototype label : AB2C_oP8_51_e_be_f
Strukturbericht designation : None
Pearson symbol : oP8
Space group number : 51
Space group symbol : $Pmma$
AFLOW prototype command : aflow --proto=AB2C_oP8_51_e_be_f
--params=
$a$,$b/a$,$c/a$,$z_{2}$,$z_{3}$,$z_{4}$


Other compounds with this structure

  • Ni3(Bi,Pb)2S2

  • (Fleet, 1973) states that parkerite is a derivative of the shandite (Ni3Pb2S2) structure, and changes to shandite if more than 4% of the bismuth is replaced by lead.
  • The Ni–II (2e) site is occupied 50% of the time, given the observed stoichiometry.
  • Earlier sources give parkerite a monoclinic structure. This may be due to an ordering of the nickel atoms at lower temperature. We follow (Downs, 2003) and use the orthorhombic structure.
  • (Fleet, 1973) describes the structure in the $Pmam$ setting of space group #51. We used FINDSYM to transform it to the standard $Pmma$ setting.

Simple Orthorhombic primitive vectors:

\[ \begin{array}{ccc} \mathbf{a}_1 & = & a \, \mathbf{\hat{x}} \\ \mathbf{a}_2 & = & b \, \mathbf{\hat{y}} \\ \mathbf{a}_3 & = & c \, \mathbf{\hat{z}} \\ \end{array} \]

Basis vectors:

\[ \begin{array}{ccccccc} & & \mbox{Lattice Coordinates} & & \mbox{Cartesian Coordinates} &\mbox{Wyckoff Position} & \mbox{Atom Type} \\ \mathbf{B}_{1} & = & \frac{1}{2} \, \mathbf{a}_{2} & = & \frac{1}{2}b \, \mathbf{\hat{y}} & \left(2b\right) & \mbox{Ni I} \\ \mathbf{B}_{2} & = & \frac{1}{2} \, \mathbf{a}_{1} + \frac{1}{2} \, \mathbf{a}_{2} & = & \frac{1}{2}a \, \mathbf{\hat{x}} + \frac{1}{2}b \, \mathbf{\hat{y}} & \left(2b\right) & \mbox{Ni I} \\ \mathbf{B}_{3} & = & \frac{1}{4} \, \mathbf{a}_{1} + z_{2} \, \mathbf{a}_{3} & = & \frac{1}{4}a \, \mathbf{\hat{x}} + z_{2}c \, \mathbf{\hat{z}} & \left(2e\right) & \mbox{Bi} \\ \mathbf{B}_{4} & = & \frac{3}{4} \, \mathbf{a}_{1}-z_{2} \, \mathbf{a}_{3} & = & \frac{3}{4}a \, \mathbf{\hat{x}}-z_{2}c \, \mathbf{\hat{z}} & \left(2e\right) & \mbox{Bi} \\ \mathbf{B}_{5} & = & \frac{1}{4} \, \mathbf{a}_{1} + z_{3} \, \mathbf{a}_{3} & = & \frac{1}{4}a \, \mathbf{\hat{x}} + z_{3}c \, \mathbf{\hat{z}} & \left(2e\right) & \mbox{Ni II} \\ \mathbf{B}_{6} & = & \frac{3}{4} \, \mathbf{a}_{1}-z_{3} \, \mathbf{a}_{3} & = & \frac{3}{4}a \, \mathbf{\hat{x}}-z_{3}c \, \mathbf{\hat{z}} & \left(2e\right) & \mbox{Ni II} \\ \mathbf{B}_{7} & = & \frac{1}{4} \, \mathbf{a}_{1} + \frac{1}{2} \, \mathbf{a}_{2} + z_{4} \, \mathbf{a}_{3} & = & \frac{1}{4}a \, \mathbf{\hat{x}} + \frac{1}{2}b \, \mathbf{\hat{y}} + z_{4}c \, \mathbf{\hat{z}} & \left(2f\right) & \mbox{S} \\ \mathbf{B}_{8} & = & \frac{3}{4} \, \mathbf{a}_{1} + \frac{1}{2} \, \mathbf{a}_{2}-z_{4} \, \mathbf{a}_{3} & = & \frac{3}{4}a \, \mathbf{\hat{x}} + \frac{1}{2}b \, \mathbf{\hat{y}}-z_{4}c \, \mathbf{\hat{z}} & \left(2f\right) & \mbox{S} \\ \end{array} \]

References

  • M. E. Fleet, The Crystal Structure of Parkerite (Ni3Bi2S2), Am. Mineral. 58, 435–439 (1973).
  • R. T. Downs and M. Hall–Wallace, The American Mineralogist Crystal Structure Database, Am. Mineral. 88, 247–250 (2003).

Geometry files


Prototype Generator

aflow --proto=AB2C_oP8_51_e_be_f --params=

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