Single-crystal neutron diffraction in diamond anvil cells with hot neutrons

It is demonstrated that it is possible to perform single-crystal measurements in diamond anvil cells (DACs) with a monochromatic beam at modern hot neutron sources that offer the benefit of short neutron wavelengths with high fluxes. A piston–cylinder DAC with conical Boehler–Almax diamonds that allows for a wide accessibility of the reciprocal space has been developed. The diffraction data collected in this cell using hot neutrons are of very good quality and can be used for a full and reliable structure refinement.

Computing details

(I)

Crystal data

Fe4MnSi3	Orientation matrix based on 12 centered reflections
Mr = 362.6	Dx = 6.331 Mg m^−3
Hexagonal, P63/mcm	X-ray radiation, λ = 1.17 Å
Hall symbol: -P 6c;-2	Cell parameters from 12 reflections
a = 6.80 (1) Å	θ = 33–36°
c = 4.75 (4) Å	µ = 0.02 mm^−1
V = 190.2 (16) Å^3	T = 293 K
Z = 2	0.2, black
F(000) = 95.315	0.45 × 0.48 × 0.9 mm

Data collection

4-circle diffractometer	Rint = 0.108
Radiation source: reactor	θmax = 48.7°, θmin = 5.7°
ω scans	h = −8→8
831 measured reflections	k = −8→8
60 independent reflections	l = −4→5
52 reflections with I > 3σ(I)

Refinement

Refinement on F	0 restraints
R[F^2 > 2σ(F^2)] = 0.078	0 constraints
wR(F^2) = 0.065	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
S = 3.15	(Δ/σ)max = 0.0002
60 reflections	Δρmax = 2.66 e Å^−3
12 parameters	Δρmin = −2.17 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Mn1	0.7577 (16)	0.7577 (16)	0.25	0.017 (5)	0.30 (3)
Fe1	0.7577 (16)	0.7577 (16)	0.25	0.017 (5)	0.70 (3)
Fe2	0.666667	0.333333	0	0.0101 (19)
Si1	0.3997 (16)	0.3997 (16)	0.25	0.011 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mn1	0.022 (5)	0.022 (5)	0.009 (11)	0.012 (5)	0	0
Fe1	0.022 (5)	0.022 (5)	0.009 (11)	0.012 (5)	0	0
Fe2	0.0105 (18)	0.0105 (18)	0.009 (4)	0.0052 (9)	0	0
Si1	0.011 (5)	0.011 (5)	0.011 (13)	0.006 (5)	0	0

Bond lengths (Å)

Mn1—Mn1^i	2.853 (18)	Fe1—Fe1^iii	2.89 (3)
Mn1—Mn1^ii	2.853 (18)	Fe1—Fe1^iv	2.89 (3)
Mn1—Mn1^iii	2.89 (3)	Fe1—Fe1^v	2.89 (3)
Mn1—Mn1^iv	2.89 (3)	Fe1—Fe1^vi	2.89 (3)
Mn1—Mn1^v	2.89 (3)	Fe1—Fe2	2.887 (16)
Mn1—Mn1^vi	2.89 (3)	Fe1—Fe2^vii	2.887 (16)
Mn1—Fe1	0	Fe1—Fe2^viii	2.887 (16)
Mn1—Fe1^i	2.853 (18)	Fe1—Fe2^ix	2.887 (16)
Mn1—Fe1^ii	2.853 (18)	Fe1—Si1	2.435 (15)
Mn1—Fe1^iii	2.89 (3)	Fe1—Si1^x	2.37 (2)
Mn1—Fe1^iv	2.89 (3)	Fe1—Si1^xi	2.37 (2)
Mn1—Fe1^v	2.89 (3)	Fe1—Si1^xii	2.61 (4)
Mn1—Fe1^vi	2.89 (3)	Fe1—Si1^vii	2.61 (4)
Mn1—Fe2	2.887 (16)	Fe2—Fe2^xiii	2.38 (4)
Mn1—Fe2^vii	2.887 (16)	Fe2—Fe2^ix	2.38 (4)
Mn1—Fe2^viii	2.887 (16)	Fe2—Si1	2.393 (15)
Mn1—Fe2^ix	2.887 (16)	Fe2—Si1^xiv	2.393 (18)
Mn1—Si1	2.435 (15)	Fe2—Si1^xi	2.393 (16)
Mn1—Si1^x	2.37 (2)	Fe2—Si1^xii	2.393 (15)
Mn1—Si1^xi	2.37 (2)	Fe2—Si1^xv	2.393 (16)
Mn1—Si1^xii	2.61 (4)	Fe2—Si1^v	2.393 (18)
Mn1—Si1^vii	2.61 (4)	Si1—Si1^xii	2.74 (4)
Fe1—Fe1^i	2.853 (18)	Si1—Si1^vii	2.74 (4)
Fe1—Fe1^ii	2.853 (18)

Symmetry codes: (i) −y+2, x−y+1, z; (ii) −x+y+1, −x+2, z; (iii) y, −x+y+1, z−1/2; (iv) y, −x+y+1, z+1/2; (v) x−y+1, x, z−1/2; (vi) x−y+1, x, z+1/2; (vii) −x+1, −y+1, z+1/2; (viii) −x+1, −y+1, −z; (ix) x, y, −z+1/2; (x) −y+1, x−y+1, z; (xi) −x+y+1, −x+1, z; (xii) −x+1, −y+1, z−1/2; (xiii) x, y, −z−1/2; (xiv) −y+1, x−y, z; (xv) y, −x+y, z−1/2.