The compression mechanism of CrF3

Jørgensen, J.-E.; Marshall, W.G.; Smith, R.I.

doi:10.1107/S010876810402316X

The compression mechanism of CrF₃

J.-E. Jørgensen, W. G. Marshall and R. I. Smith

The structure of CrF₃ has been studied in the pressure range from ambient to 9.12 GPa by time-of-flight neutron powder diffraction. Rietveld refinements of the crystal structure were performed in the space group $R\overline 3 c$ for all the recorded data sets. It was found that volume reduction is achieved through rotation of the CrF₆ octahedra and that the Cr-F-Cr bond angle decreases from 144.80 (7) to 133.9 (4)° within the investigated pressure range. Furthermore, a small octahedral strain was found to develop during compression. The octahedral strain reflects an elongation of the CrF₆ octahedra along the c-axis direction. The zero-pressure bulk modulus B_o and its pressure derivative B $_o^{\prime}$ were determined to be B_o = 29.2 (4) GPa and $B^{\prime}_o$ = 10.1 (3).

Keywords: compression mechanism; neutron powder diffraction.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S010876810402316X/ck5004sup1.cif Contains datablocks manuscript-1, manuscript-2, manuscript-3, manuscript-4, manuscript-5, manuscript-6, manuscript-7, manuscript-8
	Text file https://doi.org/10.1107/S010876810402316X/ck50041sup2.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50042sup3.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50043sup4.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50044sup5.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50045sup6.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50046sup7.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50047sup8.txt Supplementary material
	Text file https://doi.org/10.1107/S010876810402316X/ck50048sup9.txt Supplementary material

Computing details top

Figures top

(manuscript-1) Chromium Fluoride top

Crystal data top

CrF₃	V = 284.53 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.9863 (2) Å	?, ? × ? × ? mm
c = 13.2142 (7) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.045	? data points
R_exp = ?

Crystal data top

CrF₃	V = 284.53 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.9863 (2) Å	?, ? × ? × ? mm
c = 13.2142 (7) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.045	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.0032 (6)
F1	0.6153 (3)	0	0.25	0.0063 (3)

(manuscript-2) Chromium Fluoride top

Crystal data top

CrF₃	V = 276.25 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.9106 (2) Å	?, ? × ? × ? mm
c = 13.2286 (9) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.053	? data points
R_exp = ?

Crystal data top

CrF₃	V = 276.25 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.9106 (2) Å	?, ? × ? × ? mm
c = 13.2286 (9) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.053	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.0008 (7)
F1	0.6271 (3)	0	0.25	0.0063 (4)

(manuscript-3) Chromium Fluoride top

Crystal data top

CrF₃	V = 270.60 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.8593 (2) Å	?, ? × ? × ? mm
c = 13.2329 (9) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.043	? data points
R_exp = ?

Crystal data top

CrF₃	V = 270.60 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.8593 (2) Å	?, ? × ? × ? mm
c = 13.2329 (9) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.043	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.0021 (7)
F1	0.6338 (3)	0	0.25	0.0063 (4)

(manuscript-4) Chromium Fluoride top

Crystal data top

CrF₃	V = 262.59 (3) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.7860 (3) Å	?, ? × ? × ? mm
c = 13.237 (1) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.060	? data points
R_exp = ?

Crystal data top

CrF₃	V = 262.59 (3) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.7860 (3) Å	?, ? × ? × ? mm
c = 13.237 (1) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.060	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.003 (1)
F1	0.6419 (6)	0	0.25	0.0061 (5)

(manuscript-5) Chromium Fluoride top

Crystal data top

CrF₃	V = 254.94 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.7189 (2) Å	?, ? × ? × ? mm
c = 13.219 (1) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.055	? data points
R_exp = ?

Crystal data top

CrF₃	V = 254.94 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.7189 (2) Å	?, ? × ? × ? mm
c = 13.219 (1) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.055	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.0018 (9)
F1	0.6514 (8)	0	0.25	0.0063 (4)

(manuscript-6) Chromium Fluoride top

Crystal data top

CrF₃	V = 248.50 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.6639 (2) Å	?, ? × ? × ? mm
c = 13.192 (1) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.052	? data points
R_exp = ?

Crystal data top

CrF₃	V = 248.50 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.6639 (2) Å	?, ? × ? × ? mm
c = 13.192 (1) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.052	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.0017 (7)
F1	0.658 (1)	0	0.25	0.0058 (3)

(manuscript-7) Chromium Fluoride top

Crystal data top

CrF₃	V = 245.39 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.6382 (2) Å	?, ? × ? × ? mm
c = 13.172 (1) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.057	? data points
R_exp = ?

Crystal data top

CrF₃	V = 245.39 (2) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.6382 (2) Å	?, ? × ? × ? mm
c = 13.172 (1) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.057	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.0010 (8)
F1	0.660 (1)	0	0.25	0.0044 (4)

(manuscript-8) Chromium Fluoride top

Crystal data top

CrF₃	V = 243.99 (3) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.6265 (3) Å	?, ? × ? × ? mm
c = 13.163 (1) Å

Data collection top

Radiation source: ISIS spallation neutron source

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.053	? data points
R_exp = ?

Crystal data top

CrF₃	V = 243.99 (3) Å³
M_r = 108.99	Z = 6
Hexagonal, R3c	Neutron radiation, λ = ? Å
a = 4.6265 (3) Å	?, ? × ? × ? mm
c = 13.163 (1) Å

Data collection top

Refinement top

R_p = ?	χ² = NOT FOUND
R_wp = 0.053	? data points
R_exp = ?

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0	0	0	0.001 (1)
F1	0.659 (1)	0	0.25	0.0021 (4)

Experimental details

	(manuscript-1)	(manuscript-2)	(manuscript-3)	(manuscript-4)
Crystal data
Chemical formula	CrF₃	CrF₃	CrF₃	CrF₃
M_r	108.99	108.99	108.99	108.99
Crystal system, space group	Hexagonal, R3c	Hexagonal, R3c	Hexagonal, R3c	Hexagonal, R3c
Temperature (K)	?	?	?	?
a, c (Å)	4.9863 (2), 13.2142 (7)	4.9106 (2), 13.2286 (9)	4.8593 (2), 13.2329 (9)	4.7860 (3), 13.237 (1)
V (Å³)	284.53 (2)	276.25 (2)	270.60 (2)	262.59 (3)
Z	6	6	6	6
Radiation type	Neutron, λ = ? Å	Neutron, λ = ? Å	Neutron, λ = ? Å	Neutron, λ = ? Å
Specimen shape, size (mm)	?, ? × ? × ?	?, ? × ? × ?	?, ? × ? × ?	?, ? × ? × ?

Data collection
Diffractometer	?	?	?	?
Specimen mounting	?	?	?	?
Data collection mode	?	?	?	?
Scan method	?	?	?	?
2θ values (°)	2θ_min = ? 2θ_max = ? 2θ_step = ?	2θ_min = ? 2θ_max = ? 2θ_step = ?	2θ_min = ? 2θ_max = ? 2θ_step = ?	2θ_min = ? 2θ_max = ? 2θ_step = ?

Refinement
R factors and goodness of fit	R_p = ?, R_wp = 0.045, R_exp = ?, χ² = NOT FOUND	R_p = ?, R_wp = 0.053, R_exp = ?, χ² = NOT FOUND	R_p = ?, R_wp = 0.043, R_exp = ?, χ² = NOT FOUND	R_p = ?, R_wp = 0.060, R_exp = ?, χ² = NOT FOUND
No. of data points	?	?	?	?
No. of parameters	?	?	?	?
No. of restraints	?	?	?	?

	(manuscript-5)	(manuscript-6)	(manuscript-7)	(manuscript-8)
Crystal data
Chemical formula	CrF₃	CrF₃	CrF₃	CrF₃
M_r	108.99	108.99	108.99	108.99
Crystal system, space group	Hexagonal, R3c	Hexagonal, R3c	Hexagonal, R3c	Hexagonal, R3c
Temperature (K)	?	?	?	?
a, c (Å)	4.7189 (2), 13.219 (1)	4.6639 (2), 13.192 (1)	4.6382 (2), 13.172 (1)	4.6265 (3), 13.163 (1)
V (Å³)	254.94 (2)	248.50 (2)	245.39 (2)	243.99 (3)
Z	6	6	6	6
Radiation type	Neutron, λ = ? Å	Neutron, λ = ? Å	Neutron, λ = ? Å	Neutron, λ = ? Å
Specimen shape, size (mm)	?, ? × ? × ?	?, ? × ? × ?	?, ? × ? × ?	?, ? × ? × ?

Data collection
Diffractometer	?	?	?	?
Specimen mounting	?	?	?	?
Data collection mode	?	?	?	?
Scan method	?	?	?	?
2θ values (°)	2θ_min = ? 2θ_max = ? 2θ_step = ?	2θ_min = ? 2θ_max = ? 2θ_step = ?	2θ_min = ? 2θ_max = ? 2θ_step = ?	2θ_min = ? 2θ_max = ? 2θ_step = ?

Refinement
R factors and goodness of fit	R_p = ?, R_wp = 0.055, R_exp = ?, χ² = NOT FOUND	R_p = ?, R_wp = 0.052, R_exp = ?, χ² = NOT FOUND	R_p = ?, R_wp = 0.057, R_exp = ?, χ² = NOT FOUND	R_p = ?, R_wp = 0.053, R_exp = ?, χ² = NOT FOUND
No. of data points	?	?	?	?
No. of parameters	?	?	?	?
No. of restraints	?	?	?	?

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The compression mechanism of CrF₃

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