Download citation
Download citation
link to html
Determining atomic positions in thin films by X-ray diffraction is, at present, a task reserved for synchrotron facilities. Here an experimental method is presented which enables the determination of the structure factor amplitudes of thin films using laboratory-based equipment (Cu Kα radiation). This method was tested using an epitaxial 130 nm film of CuMnAs grown on top of a GaAs substrate, which unlike the orthorhombic bulk phase forms a crystal structure with tetragonal symmetry. From the set of structure factor moduli obtained by applying this method, the solution and refinement of the crystal structure of the film has been possible. The results are supported by consistent high-resolution scanning transmission electron microscopy and stoichiometry analyses.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S002188981302414X/rg5041sup1.cif
Contains datablocks global, cma_xl_anis

Computing details top

Program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

(cma_xl_anis) top
Crystal data top
As0.84Cu1.08Mn0.94γ = 90.00 (2)°
Mr = 193.40V = 92.2 (4) Å3
2, P4/nmmZ = 2
a = 3.82 (1) ÅF(000) = 174
b = 3.82 (1) ÅDx = 6.967 Mg m3
c = 6.318 (10) ŵ = 85.38 mm1
α = 90.00 (2)°T = 293 K
β = 90.00 (2)°2.00 × 2.00 × 2.00 mm
Data collection top
Radiation source: fine-focus sealed tubeRint = 0.000
Graphite monochromatorθmax = 49.4°, θmin = 7.0°
34 measured reflectionsh = 02
34 independent reflectionsk = 03
10 reflections with I > 2σ(I)l = 16
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.046Secondary atom site location: difference Fourier map
wR(F2) = 0.107 w = 1/[σ2(Fo2) + (0.1P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.39(Δ/σ)max = 0.001
34 reflectionsΔρmax = 0.83 e Å3
3 parametersΔρmin = 0.53 e Å3
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cu0.25000.75000.50000.045 (5)
As0.75000.75000.2347 (13)0.016 (3)0.96
Mn0.75000.75000.830 (3)0.024 (5)0.86
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu0.025 (6)0.025 (6)0.085 (11)0.0000.0000.000
As0.013 (4)0.013 (4)0.020 (5)0.0000.0000.000
Mn0.016 (6)0.016 (6)0.038 (12)0.0000.0000.000
Geometric parameters (Å, º) top
Cu—Asi2.541 (7)As—Cuvii2.541 (7)
Cu—Asii2.541 (7)As—Cuiii2.541 (7)
Cu—Asiii2.541 (7)As—Mniii2.732 (8)
Cu—As2.541 (7)As—Mnviii2.732 (8)
Cu—Cuiv2.701 (7)As—Mnix2.732 (8)
Cu—Cui2.701 (7)As—Mni2.732 (8)
Cu—Cuiii2.701 (7)Mn—Asx2.56 (2)
Cu—Cuv2.701 (7)Mn—Asiii2.732 (8)
Cu—Mn2.827 (15)Mn—Asviii2.732 (8)
Cu—Mniii2.827 (15)Mn—Asi2.732 (8)
Cu—Mnii2.827 (15)Mn—Asix2.732 (8)
Cu—Mni2.827 (15)Mn—Cuiii2.827 (15)
As—Mnvi2.56 (2)Mn—Cuvii2.827 (15)
As—Cui2.541 (7)Mn—Cui2.827 (15)
Asi—Cu—Asii115.79 (18)Mnvi—As—Cuiii131.27 (16)
Asi—Cu—Asiii97.5 (3)Cui—As—Cuiii97.5 (3)
Asii—Cu—Asiii115.79 (18)Cuvii—As—Cuiii64.21 (18)
Asi—Cu—As115.79 (18)Mnvi—As—Cu131.27 (16)
Asii—Cu—As97.5 (3)Cui—As—Cu64.21 (18)
Asiii—Cu—As115.79 (18)Cuvii—As—Cu97.5 (3)
Asi—Cu—Cuiv122.10 (9)Cuiii—As—Cu64.21 (18)
Asii—Cu—Cuiv57.90 (9)Mnvi—As—Mniii81.4 (4)
Asiii—Cu—Cuiv57.90 (9)Cui—As—Mniii128.6 (3)
As—Cu—Cuiv122.10 (9)Cuvii—As—Mniii128.6 (3)
Asi—Cu—Cui57.90 (9)Cuiii—As—Mniii64.7 (3)
Asii—Cu—Cui122.10 (9)Cu—As—Mniii64.7 (3)
Asiii—Cu—Cui122.10 (9)Mnvi—As—Mnviii81.4 (4)
As—Cu—Cui57.90 (9)Cui—As—Mnviii64.7 (3)
Cuiv—Cu—Cui180.0Cuvii—As—Mnviii64.7 (3)
Asi—Cu—Cuiii122.10 (9)Cuiii—As—Mnviii128.6 (3)
Asii—Cu—Cuiii122.10 (9)Cu—As—Mnviii128.6 (3)
Asiii—Cu—Cuiii57.90 (9)Mniii—As—Mnviii162.8 (8)
As—Cu—Cuiii57.90 (9)Mnvi—As—Mnix81.4 (4)
Cuiv—Cu—Cuiii90.0Cui—As—Mnix128.6 (3)
Cui—Cu—Cuiii90.0Cuvii—As—Mnix64.7 (3)
Asi—Cu—Cuv57.90 (9)Cuiii—As—Mnix64.7 (3)
Asii—Cu—Cuv57.90 (9)Cu—As—Mnix128.6 (3)
Asiii—Cu—Cuv122.10 (9)Mniii—As—Mnix88.73 (11)
As—Cu—Cuv122.10 (9)Mnviii—As—Mnix88.73 (11)
Cuiv—Cu—Cuv90.0Mnvi—As—Mni81.4 (4)
Cui—Cu—Cuv90.0Cui—As—Mni64.7 (3)
Cuiii—Cu—Cuv180.0Cuvii—As—Mni128.6 (3)
Asi—Cu—Mn60.9 (2)Cuiii—As—Mni128.6 (3)
Asii—Cu—Mn173.8 (3)Cu—As—Mni64.7 (3)
Asiii—Cu—Mn60.9 (2)Mniii—As—Mni88.73 (11)
As—Cu—Mn88.8 (4)Mnviii—As—Mni88.73 (11)
Cuiv—Cu—Mn118.54 (16)Mnix—As—Mni162.8 (8)
Cui—Cu—Mn61.46 (16)Asx—Mn—Asiii98.6 (4)
Cuiii—Cu—Mn61.46 (16)Asx—Mn—Asviii98.6 (4)
Cuv—Cu—Mn118.54 (16)Asiii—Mn—Asviii162.8 (8)
Asi—Cu—Mniii173.8 (3)Asx—Mn—Asi98.6 (4)
Asii—Cu—Mniii60.9 (2)Asiii—Mn—Asi88.73 (11)
Asiii—Cu—Mniii88.8 (4)Asviii—Mn—Asi88.73 (11)
As—Cu—Mniii60.9 (2)Asx—Mn—Asix98.6 (4)
Cuiv—Cu—Mniii61.46 (16)Asiii—Mn—Asix88.73 (11)
Cui—Cu—Mniii118.54 (16)Asviii—Mn—Asix88.73 (11)
Cuiii—Cu—Mniii61.46 (16)Asi—Mn—Asix162.8 (8)
Cuv—Cu—Mniii118.54 (16)Asx—Mn—Cu137.5 (3)
Mn—Cu—Mniii122.9 (3)Asiii—Mn—Cu54.4 (2)
Asi—Cu—Mnii60.9 (2)Asviii—Mn—Cu111.3 (5)
Asii—Cu—Mnii88.8 (4)Asi—Mn—Cu54.4 (2)
Asiii—Cu—Mnii60.9 (2)Asix—Mn—Cu111.3 (5)
As—Cu—Mnii173.8 (3)Asx—Mn—Cuiii137.5 (3)
Cuiv—Cu—Mnii61.46 (16)Asiii—Mn—Cuiii54.4 (2)
Cui—Cu—Mnii118.54 (16)Asviii—Mn—Cuiii111.3 (5)
Cuiii—Cu—Mnii118.54 (16)Asi—Mn—Cuiii111.3 (5)
Cuv—Cu—Mnii61.46 (16)Asix—Mn—Cuiii54.4 (2)
Mn—Cu—Mnii85.0 (6)Cu—Mn—Cuiii57.1 (3)
Mniii—Cu—Mnii122.9 (3)Asx—Mn—Cuvii137.5 (3)
Asi—Cu—Mni88.8 (4)Asiii—Mn—Cuvii111.3 (5)
Asii—Cu—Mni60.9 (2)Asviii—Mn—Cuvii54.4 (2)
Asiii—Cu—Mni173.8 (3)Asi—Mn—Cuvii111.3 (5)
As—Cu—Mni60.9 (2)Asix—Mn—Cuvii54.4 (2)
Cuiv—Cu—Mni118.54 (17)Cu—Mn—Cuvii85.0 (6)
Cui—Cu—Mni61.46 (16)Cuiii—Mn—Cuvii57.1 (3)
Cuiii—Cu—Mni118.54 (16)Asx—Mn—Cui137.5 (3)
Cuv—Cu—Mni61.46 (16)Asiii—Mn—Cui111.3 (5)
Mn—Cu—Mni122.9 (3)Asviii—Mn—Cui54.4 (2)
Mniii—Cu—Mni85.0 (6)Asi—Mn—Cui54.4 (2)
Mnii—Cu—Mni122.9 (3)Asix—Mn—Cui111.3 (5)
Mnvi—As—Cui131.27 (16)Cu—Mn—Cui57.1 (3)
Mnvi—As—Cuvii131.27 (16)Cuiii—Mn—Cui85.0 (6)
Cui—As—Cuvii64.21 (18)Cuvii—Mn—Cui57.1 (3)
Symmetry codes: (i) x+1, y+2, z+1; (ii) x1, y, z; (iii) x+1, y+1, z+1; (iv) x, y+1, z+1; (v) x, y+2, z+1; (vi) x, y, z1; (vii) x+1, y, z; (viii) x+2, y+2, z+1; (ix) x+2, y+1, z+1; (x) x, y, z+1.
 

Follow J. Appl. Cryst.
Sign up for e-alerts
Follow J. Appl. Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds