NH4HF2 ($F5_{8}$) Structure : A2BC_oP16_53_eh_ab_g

Picture of Structure; Click for Big Picture
Prototype : F2H5N
AFLOW prototype label : A2BC_oP16_53_eh_ab_g
Strukturbericht designation : $F5_{8}$
Pearson symbol : oP16
Space group number : 53
Space group symbol : $Pmna$
AFLOW prototype command : aflow --proto=A2BC_oP16_53_eh_ab_g
--params=
$a$,$b/a$,$c/a$,$x_{3}$,$y_{4}$,$y_{5}$,$z_{5}$


  • This structure was first investigated by (Pauling, 1933) and assigned Strukturbericht designation $F5_{8}$ by (Gottfried, 1937). It was reinvestigated by (Rogers, 1940). Neither paper notes the positions of the hydrogen atoms, but under the assumption that the structure is similar to KHF2 ($F5_{2}$), (Downs, 2003) puts some of them the atoms between pairs of fluorine atoms. The remaining hydrogen atoms are part of the NH4 radical.
  • The crystal structure was given in the $Pman$ setting of space group #53. We used FINDSYM to change it to the standard $Pmna$ structure.

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} & = & 0 \, \mathbf{a}_{1} + 0 \, \mathbf{a}_{2} + 0 \, \mathbf{a}_{3} & = & 0 \, \mathbf{\hat{x}} + 0 \, \mathbf{\hat{y}} + 0 \, \mathbf{\hat{z}} & \left(2a\right) & \mbox{H I} \\ \mathbf{B}_{2} & = & \frac{1}{2} \, \mathbf{a}_{1} + \frac{1}{2} \, \mathbf{a}_{3} & = & \frac{1}{2}a \, \mathbf{\hat{x}} + \frac{1}{2}c \, \mathbf{\hat{z}} & \left(2a\right) & \mbox{H I} \\ \mathbf{B}_{3} & = & \frac{1}{2} \, \mathbf{a}_{1} & = & \frac{1}{2}a \, \mathbf{\hat{x}} & \left(2b\right) & \mbox{H II} \\ \mathbf{B}_{4} & = & \frac{1}{2} \, \mathbf{a}_{3} & = & \frac{1}{2}c \, \mathbf{\hat{z}} & \left(2b\right) & \mbox{H II} \\ \mathbf{B}_{5} & = & x_{3} \, \mathbf{a}_{1} & = & x_{3}a \, \mathbf{\hat{x}} & \left(4e\right) & \mbox{F I} \\ \mathbf{B}_{6} & = & \left(\frac{1}{2} - x_{3}\right) \, \mathbf{a}_{1} + \frac{1}{2} \, \mathbf{a}_{3} & = & \left(\frac{1}{2}-x_{3}\right)a \, \mathbf{\hat{x}} + \frac{1}{2}c \, \mathbf{\hat{z}} & \left(4e\right) & \mbox{F I} \\ \mathbf{B}_{7} & = & -x_{3} \, \mathbf{a}_{1} & = & -x_{3}a \, \mathbf{\hat{x}} & \left(4e\right) & \mbox{F I} \\ \mathbf{B}_{8} & = & \left(\frac{1}{2} +x_{3}\right) \, \mathbf{a}_{1} + \frac{1}{2} \, \mathbf{a}_{3} & = & \left(\frac{1}{2} +x_{3}\right)a \, \mathbf{\hat{x}} + \frac{1}{2}c \, \mathbf{\hat{z}} & \left(4e\right) & \mbox{F I} \\ \mathbf{B}_{9} & = & \frac{1}{4} \, \mathbf{a}_{1} + y_{4} \, \mathbf{a}_{2} + \frac{1}{4} \, \mathbf{a}_{3} & = & \frac{1}{4}a \, \mathbf{\hat{x}} + y_{4}b \, \mathbf{\hat{y}} + \frac{1}{4}c \, \mathbf{\hat{z}} & \left(4g\right) & \mbox{NH$_{4}$} \\ \mathbf{B}_{10} & = & \frac{1}{4} \, \mathbf{a}_{1}-y_{4} \, \mathbf{a}_{2} + \frac{3}{4} \, \mathbf{a}_{3} & = & \frac{1}{4}a \, \mathbf{\hat{x}}-y_{4}b \, \mathbf{\hat{y}} + \frac{3}{4}c \, \mathbf{\hat{z}} & \left(4g\right) & \mbox{NH$_{4}$} \\ \mathbf{B}_{11} & = & \frac{3}{4} \, \mathbf{a}_{1}-y_{4} \, \mathbf{a}_{2} + \frac{3}{4} \, \mathbf{a}_{3} & = & \frac{3}{4}a \, \mathbf{\hat{x}}-y_{4}b \, \mathbf{\hat{y}} + \frac{3}{4}c \, \mathbf{\hat{z}} & \left(4g\right) & \mbox{NH$_{4}$} \\ \mathbf{B}_{12} & = & \frac{3}{4} \, \mathbf{a}_{1} + y_{4} \, \mathbf{a}_{2} + \frac{1}{4} \, \mathbf{a}_{3} & = & \frac{3}{4}a \, \mathbf{\hat{x}} + y_{4}b \, \mathbf{\hat{y}} + \frac{1}{4}c \, \mathbf{\hat{z}} & \left(4g\right) & \mbox{NH$_{4}$} \\ \mathbf{B}_{13} & = & y_{5} \, \mathbf{a}_{2} + z_{5} \, \mathbf{a}_{3} & = & y_{5}b \, \mathbf{\hat{y}} + z_{5}c \, \mathbf{\hat{z}} & \left(4h\right) & \mbox{F II} \\ \mathbf{B}_{14} & = & \frac{1}{2} \, \mathbf{a}_{1}-y_{5} \, \mathbf{a}_{2} + \left(\frac{1}{2} +z_{5}\right) \, \mathbf{a}_{3} & = & \frac{1}{2}a \, \mathbf{\hat{x}}-y_{5}b \, \mathbf{\hat{y}} + \left(\frac{1}{2} +z_{5}\right)c \, \mathbf{\hat{z}} & \left(4h\right) & \mbox{F II} \\ \mathbf{B}_{15} & = & \frac{1}{2} \, \mathbf{a}_{1} + y_{5} \, \mathbf{a}_{2} + \left(\frac{1}{2} - z_{5}\right) \, \mathbf{a}_{3} & = & \frac{1}{2}a \, \mathbf{\hat{x}} + y_{5}b \, \mathbf{\hat{y}} + \left(\frac{1}{2}-z_{5}\right)c \, \mathbf{\hat{z}} & \left(4h\right) & \mbox{F II} \\ \mathbf{B}_{16} & = & -y_{5} \, \mathbf{a}_{2}-z_{5} \, \mathbf{a}_{3} & = & -y_{5}b \, \mathbf{\hat{y}}-z_{5}c \, \mathbf{\hat{z}} & \left(4h\right) & \mbox{F II} \\ \end{array} \]

References

  • M. T. Rogers and L. Helmholz, A Redetermination of the Parameters in Ammonium Bifluoride, J. Am. Chem. Soc. 62, 1533–1536 (1940), doi:10.1021/ja01863a057.
  • L. Pauling, The Crystal Structure of Ammonium Hydrogen Fluoride, NH4HF2, Zeitschrift für Kristallographie – Crystalline Materials 85, 380–391 (1933), doi:10.1524/zkri.1933.85.1.380.
  • C. Gottfried and F. Schossberger, eds., Strukturbericht Band III 1933–1935 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1937).

Found in

  • 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=A2BC_oP16_53_eh_ab_g --params=

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