Normal spinel CdCr2O4 and CdCr2O4/Ag nanocomposite as novel photocatalysts, for degradation of water contaminates

2018 ◽  
Vol 195 ◽  
pp. 37-49 ◽  
Author(s):  
Ali Abbasi ◽  
Hossein Khojasteh ◽  
Masood Hamadanian ◽  
Masoud Salavati-Niasari
Keyword(s):  
Normal Spinel

Die Kristallstruktur des Cyanospinells K2Cd(CN)4

1991 ◽  
Vol 46 (1) ◽  
pp. 47-49 ◽  
Author(s):  
Bernd Ziegler ◽  
Dietrich Babel
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Spinel Type ◽  
X Ray ◽  
Normal Spinel

The crystal structure of cubic K2Cd(CN)4 (a = 1286.01(9) pm, Fd 3̅ m, Z = 8) was determined from 175 independent X-ray single crystal reflections (w R = 0.0178). Regular [Cd(CN)4]2- tetrahedra (Cd - C = 222.5(3), C - N = 111.3(3) pm) and strongly trigonally elongated [KN6] octahedra ( K - N = 293.0(2) pm) are arranged in a normal spinel type manner.

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.

Magnetic disaccommodation in normal spinel structures

1991 ◽  
Vol 52 (4) ◽  
pp. 242-246 ◽  
Author(s):  
R. Torres ◽  
C. Francisco ◽  
J. M. Mu�oz
Keyword(s):  
Normal Spinel ◽  
Spinel Structures

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.

Influence of inverse spinel structured CuGa2 O4 on microwave dielectric properties of normal spinel ZnGa2 O4 ceramics

2017 ◽  
Vol 101 (4) ◽  
pp. 1646-1654 ◽  
Author(s):  
Xiaochi Lu ◽  
Wenjie Bian ◽  
Yaoyao Li ◽  
Haikui Zhu ◽  
Zhenxiao Fu ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Inverse Spinel ◽  
Microwave Dielectric ◽  
Normal Spinel

Normal spinel CuCr1.6Sb0.4S4, a new material with a giant magnetoresistance

JETP Letters ◽  
2000 ◽  
Vol 72 (11) ◽  
pp. 561-564 ◽  
Author(s):  
L. I. Koroleva ◽  
R. V. Demin ◽  
J. Warczewski ◽  
J. Krok-Kowalski ◽  
T. Mydlarz ◽  
...  
Keyword(s):  
Giant Magnetoresistance ◽  
New Material ◽  
Normal Spinel

scholarly journals Crystal Defects and Cation Redistribution Study on Nanocrystalline Cobalt-Ferri-Chromites by Positron Annihilation Spectroscopy

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Kunal B. Modi ◽  
Nimish H. Vasoya ◽  
Vinay K. Lakhani ◽  
Tushar K. Pathak ◽  
P. M. G. Nambissan
Keyword(s):  
Spinel Ferrite ◽  
Positron Annihilation Spectroscopy ◽  
Crystal Defects ◽  
X Ray Diffraction ◽  
Lattice Contraction ◽  
General Chemical ◽  
Coprecipitation Technique ◽  
Normal Spinel ◽  
Cation Redistribution ◽  
Subsequent Stabilization

Positron lifetime and Doppler broadening measurements were carried out on nanocrystalline (grain size ~60–65 nm) samples of the Cr3+-substituted cobalt ferrite system with general chemical formula CoCrxFe2−xO4 (x=0.0−2.0) synthesized by the coprecipitation technique. The results indicated selective trapping of positrons in large vacancy clusters initially at the tetrahedral (A-) sites and then with Cr3+-substitution up to concentration (x)=0.7, at the octahedral (B-) sites. The results are consistent with the cation distribution determined from X-ray diffraction line intensity calculations, which indicated partial inversion of the inverse spinel ferrite, subsequent stabilization over a range of substitution (x=0.7 to 1.7), and finally the full inversion to the normal spinel chromite (CoCr2O4, x=2.0). In the intermediate range of substitution, lattice contraction prevented a fraction of Co2+ ions released from the (B-) sites from entering the tetrahedral sites, and these vacancies at the (A-) sites trapped positrons. Although the samples were composed of nanocrystalline grains, only an insignificant fraction of positrons were diffused and annihilated at the grain surfaces, since the grain sizes and the thermal diffusion length of positrons nearly overlapped.

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