$D0_{7}$ (CrO3) (obsolete) Structure : AB3_oC16_20_a_bc

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Prototype : CrO3
AFLOW prototype label : AB3_oC16_20_a_bc
Strukturbericht designation : $D0_{7}$
Pearson symbol : oC16
Space group number : 20
Space group symbol : $C222_{1}$
AFLOW prototype command : aflow --proto=AB3_oC16_20_a_bc
--params=
$a$,$b/a$,$c/a$,$x_{1}$,$y_{2}$,$x_{3}$,$y_{3}$,$z_{3}$


  • This is the determination of the orthorhombic structure of CrO3 given the $D0_{7}$ designation by (Hermann, 1937). This structure is superceded by the one found by (Byström, 1950), which we call the orthorhombic CrO3 phase,. The current structure has the Cr atom at the center of a distorted oxygen octahedron, while the newer structure has the Cr atom at center of a distorted tetrahedron.

Base-centered Orthorhombic primitive vectors:

\[ \begin{array}{ccc} \mathbf{a}_1 & = & \frac12 \, a \, \mathbf{\hat{x}} - \frac12 \, b \, \mathbf{\hat{y}} \\ \mathbf{a}_2 & = & \frac12 \, a \, \mathbf{\hat{x}} + \frac12 \, b \, \mathbf{\hat{y}} \\ \mathbf{a}_3 & = & c \, \mathbf{\hat{z}} \\ \end{array} \]

Basis vectors:

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

References

  • H. Bräkken, Die Kristallstrukturen der Trioxyde von Chrom, Molybdän und Wolfram, Zeitschrift für Kristallographie – Crystalline Materials 78, 484–488 (1931), doi:10.1524/zkri.1931.78.1.484.
  • C. Hermann, O. Lohrmann, and H. Philipp, eds., Strukturebericht Band II, 1928–1932 (Akademsiche Verlagsgesellschaft M. B. H, Leipzig, 1937).

Found in

Geometry files


Prototype Generator

aflow --proto=AB3_oC16_20_a_bc --params=

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