research papers
γ-MoO3 nanobelts prepared by hydrothermal synthesis were studied by synchrotron radiation powder diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction. Their nm dimensions, in particular in two crystallographic directions, have a profound influence on electrochemical properties during cycling as the cathode material in lithium-ion batteries (LIBs). The diffraction analysis shows clearly that the crystal structure for the γ-MoO3 nanobelts differs significantly from that of bulk α-MoO3. The observed powder diffraction pattern, with asymmetric peaks, extremely broad peaks, as well as additional or absent diffraction peaks, is fully described by means of a model based on stacking disorder of MoO3 slabs.
Keywords: stacking faults; X-ray diffraction; diffuse scattering; transmission electron microscopy; selected area electron diffraction.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520615024804/bm5082sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520615024804/bm5082Isup2.hkl | |
Rietveld powder data file (CIF format) https://doi.org/10.1107/S2052520615024804/bm5082Isup3.rtv |
CCDC reference: 1444281
Computing details top
(I) top
Crystal data top
MoO3 | c = 13.85331 (19) Å |
Mr = 143.9 | V = 202.83 (1) Å3 |
Orthorhombic, Pmcn | Z = 4 |
Hall symbol: -P -2xa;-2ybc;-2zabc | F(000) = 264 |
a = 3.69610 (4) Å | Dx = 4.714 Mg m−3 |
b = 3.96122 (5) Å | T = 293 K |
Refinement top
Rp = 0.226 | 0 restraints |
Rwp = 0.284 | 3 constraints |
Rexp = 0.283 | Weighting scheme based on measured s.u.'s |
R(F) = 0.067 | (Δ/σ)max = 0.128 |
7300 data points | Background function: 5 Legendre polynoms |
Profile function: Pseudo-Voigt | Preferred orientation correction: none |
27 parameters |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | ||
O1 | 0.25 | 0.542 (2) | 0.0875 (7) | 0.0036 (16)* | |
Mo1 | 0.25 | 0.0814 (3) | 0.10140 (9) | 0.0069 (3)* | |
O2 | 0.25 | 0.042 (3) | 0.2216 (7) | 0.0036 (16)* | |
O3 | 0.25 | 0.497 (2) | 0.4312 (7) | 0.0036 (16)* |
Bond lengths (Å) top
Mo1—O1i | 2.144 (9) | Mo1—O3ii | 2.379 (9) |
Mo1—O1 | 1.835 (9) | Mo1—O3iii | 1.931 (3) |
Mo1—O2 | 1.673 (10) | Mo1—O3iv | 1.931 (3) |
Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, −y+1/2, z−1/2; (iii) −x, y−1/2, −z+1/2; (iv) −x+1, y−1/2, −z+1/2. |