The elimination of the ambiguity in the assignment of a space group for the spinel structure depends upon the detection of very weak `forbidden reflexions' in the presence of substantial multiple diffraction. Attention is drawn to the importance of the latter in the case of neutron diffraction ...
The crystal structure of magnesium aluminate is conventionally described within a symmetry corresponding to the centrosymmetrical space group Fd3m but this has created difficulties for the interpretation of many of its physical properties. Therefore, extensive X-ray diffraction intensity data have been col...
Structure refinement of high-pressure hexagonal aluminous phases K1.00Mg2.00Al4.80Si1.15O12 and Na Two hexagonal aluminous phases, which could serve as potential Na- and K-host minerals in the lower mantle, with compositions K1.00Mg2.00Al4.80Si1.15O12 an... KOJITANI, HIROSHI,IWABUCHI, TAKEMI,...
Experimental evidence from several sources suggests that, contrary to general belief, the crystal structure of cubic spinels is not satisfactorily referred to the space group Fd3m. The discrepancy is most likely to be associated with a small displacement of the octahedrally coordinated metal ion ...
The crystal structure of the quaternary phase was investigated by X-ray powder method and is described in the thiospinel structure (space group Fd3m) with the lattice parameter а = 0,99388(1)nm. Atomic parameters were refined in the isotropic approximation ( R I= 0.0465, R P= 0.1060). ...
The crystal structure of magnesium aluminate is conventionally described within a symmetry corresponding to the centrosymmetrical space group Fd3m but this has created difficulties for the interpretation of many of its physical properties. Therefore, extensive X-ray diffraction intensity data have been col...
spinel structure (space group) according to Rietveld refinement of the XRD pattern. By using the UV optical absorbance, it has been shown that the compound revealed significant visible-light absorption. The estimated optical band gap energy was estimated as = 2.78 eV. The dielectric results ...
They are the reflections from 111, 220, 331, 222, 400, 422, 511, 440, 620, 533 and 622 planes of the face-centered cubic (fcc) spinel structure, Fd-3m space group (JCPDS no. 22-1084) [45,47,48,49,50,51,52]. Figure 3. XRD patterns of the samples produced via (a) sol-gel...
(dcell= 8.2472) standard with the cubic spinel structure and space group ofFd3m, was used to index these peaks. The S500 exhibited an impurity phase of anatase (A, peak located at 2θ= 25.2°) and rutile (R, a peak located at 2θ= 27.4°) TiO2, which was similar to the results ...
The cubic structure of LaFe2O4 (a = b = c = 0.06551 nm and α = β = γ = 60°) with space group F4-3m was optimized using Cambridge serial total energy package (CASTEP) on Materials Studio 8.0. The exchange function of the ion-electron was preserved with projector augmented-wave ...