Tolerance Factor and Phase Stability of the Normal Spinel Structure

2020 ◽  
Vol 20 (3) ◽  
pp. 2014-2018 ◽  
Author(s):  
Zhen Song ◽  
Quanlin Liu
Keyword(s):  
Phase Stability ◽  
Spinel Structure ◽  
Tolerance Factor ◽  
Normal Spinel

Ni-Substitution Induced Inversion in ZnFe2O4 Seen by Positron Annihilation

2012 ◽  
Vol 733 ◽  
pp. 219-223 ◽  
Author(s):  
P.M.G. Nambissan ◽  
O. Mondal ◽  
C. Chakrabarty ◽  
M. Pal
Keyword(s):  
Positron Annihilation ◽  
Spinel Structure ◽  
Positron Lifetime ◽  
Drastic Change ◽  
Doppler Broadening ◽  
Positron Trapping ◽  
Normal Spinel ◽  
Ni Substitution ◽  
Positron Lifetimes ◽  
Coincidence Doppler Broadening

We report in this work about the inversion of the spinel structure of ZnFe2O4induced by the substitution of Zn2+by Ni2+ions. Positron lifetimes were measured in Zn1-xNixFe2O4with different concentrations (x) of doped Ni2+ions and a drastic change across x = 0.4 – 0.6 was observed, which is attributed to this transformation. The interchange of positions of the cations on doping leaves a fraction of them unoccupied and these vacancies act as positron trapping centres. Since Ni2+is smaller in size than Zn2+, defects due to non-stoichiometry are less in NiFe2O4than in ZnFe2O4. The increase in positron lifetime implies the trapping of positrons being shifted from A- to B-sites and is an indication of the transformation from inverse to normal spinel configuration. Coincidence Doppler broadening measurements supported these findings.

X-Ray Analysis of the New Ferrites CuCr2-xFexSe4

2010 ◽  
Vol 163 ◽  
pp. 217-220
Author(s):  
Ewa Maciążek ◽  
Grzegorz Dercz ◽  
Izabela Jendrzejewska ◽  
Tomasz Goryczka ◽  
Rafał Sitko
Keyword(s):  
Structure Determination ◽  
Spinel Structure ◽  
Rietveld Method ◽  
Structure Refinement ◽  
X Ray ◽  
Normal Spinel ◽  
Multi Phase ◽  
Sintering Method

The series of ferrites CuCr2-xFexSe4 (x=0.10.5) were obtained as polycrystalline compounds using conventional ceramics sintering method. The stoichiometric amounts of spectrally pure elements were used for synthesis. The phase and structure determination was done using X-ray analysis. The Rietveld method was applied for structure refinement. It occurred that all samples were multi-phase, the main content crystallized in cubic, normal spinel structure.

scholarly journals Tolerance factor and phase stability of the garnet structure. Corrigendum

2020 ◽  
Vol 76 (3) ◽  
pp. 311-311
Author(s):  
Zhen Song ◽  
Dandan Zhou ◽  
Quanlin Liu
Keyword(s):  
Phase Stability ◽  
Tolerance Factor ◽  
Garnet Structure ◽  
Acta Cryst

An error in an equation in the paper by Song et al. [Acta Cryst. (2019), C75, 1353–1358] is corrected.

X-Ray Analysis of the Cd0.5Ge0.5Cr2Se4 and CdCr1.9Ge0.075Se4 Compounds

2007 ◽  
Vol 130 ◽  
pp. 93-96
Author(s):  
Ewa Maciążek ◽  
Tomasz Goryczka ◽  
Izabela Jendrzejewska
Keyword(s):  
Structure Analysis ◽  
Spinel Structure ◽  
Rietveld Method ◽  
Spinel Phase ◽  
Structure Refinement ◽  
Ceramic Method ◽  
X Ray ◽  
Normal Spinel

The polycrystalline Cd0.5Ge0.5Cr2Se4 and CdCr1.9Ge0.075Se4 compounds were obtained using ceramic method. X-ray analysis was used to make phase and structure analysis. The Rietveld method was applied for structure refinement. Both compounds crystallized in cubic, normal spinel structure, Fd 3m. Besides the main spinel phase, Cr2Se3 was observed.

scholarly journals Increase of Magnetic Transition Temperatures by Reduction of Local Disorder for Perovskite Manganites

2002 ◽  
Vol 718 ◽  
Author(s):  
B. Dabrowski ◽  
O. Chmaissem ◽  
J. Mais ◽  
S. Kolesnik ◽  
J.D. Jorgensen ◽  
...  
Keyword(s):  
Oxygen Content ◽  
Phase Stability ◽  
Magnetic Transition ◽  
Structural Disorder ◽  
Tolerance Factor ◽  
Perovskite Manganites ◽  
Transition Temperatures ◽  
Local Disorder

AbstractWe report the synthesis of Sr1-xCaxMnO3 and La0.5Ba0.5MnO3 perovskites over extended cation and oxygen composition ranges and describe the dependence of their phase stability on the tolerance factor t = t(x,T,σ) that is a function of composition, temperature, and oxygen content. We show that magnetic transition temperatures depend strongly on the tolerance factor and charge disorder while dependence on the structural disorder is less important. By reducing charge and structural disorder we have significantly increased the Curie and Neel temperatures for perovskite manganites.

Normal spinel structure ZnFe2O4/g-C3N4 enhanced catalytic activity for photo-Fenton degradation of methylene blue

2019 ◽  
Vol 12 (01) ◽  
pp. 1850108 ◽  
Author(s):  
Xunhe Wang ◽  
Zhaodong Nan
Keyword(s):  
Methylene Blue ◽  
Catalytic Activity ◽  
Spinel Structure ◽  
Organic Dyes ◽  
Two Dimensional ◽  
Mixed Spinel ◽  
Normal Spinel ◽  
Excellent Stability

Heterogeneous photo-Fenton technology has been widely employed to degrade organic dyes in wasterwater. In the present study, a composite consisting of normal spinel structure ZnFe2O4 nanoparticle and two-dimensional sheet of g-C3N4 was facilely synthesized. Different characterization technologies, such as XRD, XPS and VSM, were employed to demonstrate the normal spinel structure ZnFe2O4 formation. The composite shows higher catalytic activity for degradation of methylene blue (MB) than mixed spinel structure ZnFe2O4/g-C3N4. Simultaneously, the composite exhibits excellent stability and reusability.

scholarly journals Phase stability of intercalated V2O5 battery cathodes elucidated through the Goldschmidt tolerance factor

2019 ◽  
Vol 21 (15) ◽  
pp. 7732-7744
Author(s):  
Kit McColl ◽  
Furio Corà
Keyword(s):  
Structural Stability ◽  
Phase Stability ◽  
Ionic Mobility ◽  
Tolerance Factor ◽  
Dispersion Forces

Structural stability, intercalation, layer translation, and ionic mobility investigated in α- and δ-V2O5 using hybrid-exchange DFT, including dispersion forces.

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