scholarly journals The versatile Co2+/Co3+ oxidation states in cobalt alumina spinel: how to design strong blue nanometric pigments for color electrophoretic display

RSC Advances ◽  
2019 ◽  
Vol 9 (59) ◽  
pp. 34125-34135 ◽  
Author(s):  
B. Serment ◽  
C. Brochon ◽  
G. Hadziioannou ◽  
S. Buffière ◽  
A. Demourgues ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Type Structure ◽  
Oxidation States ◽  
Inorganic Pigments ◽  
Spinel Type ◽  
Nanosized Materials ◽  
Electrophoretic Display

Blue cobalt inorganic pigments with spinel-type structure have been revisited in order to understand the origin of blackening at low temperatures and to design strong blue nanosized materials.

MAGNETIC BEHAVIOUR OF UPdAl, UCuGa AND UCuSn

1993 ◽  
Vol 07 (01n03) ◽  
pp. 850-854 ◽  
Author(s):  
V.H. TRAN ◽  
R. TROĆ
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Type Structure ◽  
Complex Structures ◽  
Temperature Dependent ◽  
Antiferromagnetic Ordering

Magnetic susceptibility and electrical resistivity have been measured on UCuGa, UCu1+xSn1−x, (x=0 and 0.1), and UPdAl. The first two compounds, crystallizing in the hexagonal CaIn2-type structure, show at low temperatures an antiferromagnetic ordering probably with complex structures. UPdAl, which adopts the orthorhombic TiNiSi-type structure, was found to be a weakly temperature-dependent paramagnet down to 4.2 K.

Deltalumite, a New Natural Modification of Alumina with a Spinel-Type Structure

2020 ◽  
Vol 62 (7) ◽  
pp. 608-617
Author(s):  
I. V. Pekov ◽  
I. P. Anikin ◽  
N. V. Chukanov ◽  
D. I. Belakovskiy ◽  
V. O. Yapaskurt ◽  
...  
Keyword(s):  
Type Structure ◽  
Spinel Type ◽  
Natural Modification

Synthesis of mixed ferrite with spinel-type structure from a stainless steelmaking solid waste

1998 ◽  
Vol 281 (2) ◽  
pp. 312-317 ◽  
Author(s):  
A. López-Delgado ◽  
J.L. Martı́n de Vidales ◽  
E. Vila ◽  
F.A. López
Keyword(s):  
Solid Waste ◽  
Type Structure ◽  
Spinel Type ◽  
Mixed Ferrite

scholarly journals How Aromatic Are Molecular Nanorings? The Case of a Six-Porphyrin Nanoring

2021 ◽  
Author(s):  
irene casademont-reig ◽  
Raúl Guerrero-Avilés ◽  
Eloy Ramos-Cordoba ◽  
Miquel Torrent-Sucarrat ◽  
Eduard Matito
Keyword(s):  
Low Temperatures ◽  
Ring Current ◽  
Computational Method ◽  
Oxidation States ◽  
Aromatic Rings ◽  
Persistent Currents ◽  
Conjugated Molecules ◽  
Strong Magnetic Fields ◽  
The Poor ◽  
Computational Calculations

<div> <div> <div> <p>Large conjugated rings give rise to novel promising structures that can sustain persistent currents at low temperatures even in the presence of strong magnetic fields. One of the most interesting such molecules was recently synthesized [Anderson et al., Nature, 2017, 541, 3512] in the form of a six-porphyrin nanoring structure, which, according to the authors, in its +6-oxidation state (c-P66+) sustained an aromatic ring current involving 78π electrons; one of the largest aromatic rings ever produced. In this paper, we have provided compelling evidence that this molecule is not aromatic, as it was incorrectly inferred from computational calculations that suffer from large delocalization errors. A thorough analysis of four oxidation states of the six-porphyrin nanoring re- veals that the main reason behind the poor aromaticity of these nanorings is the low delocalization in the transition from the porphyrins to the bridging butadiyne linkers, which disrupts the overall conjugated circuit. These results highlight the importance of choosing an adequate computational method to study large conjugated molecules and the appropriate aromaticity descriptors to identify the part of the molecule that is responsible for the loss of aromaticity. We believe the strategy here employed will be helpful in designing new large aromatic molecular nanorings. </p> </div> </div> </div>

scholarly journals Discovery of Ternary Silicon Titanium Nitride with Spinel-Type Structure

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shrikant Bhat ◽  
Abhijeet Lale ◽  
Samuel Bernard ◽  
Wei Zhang ◽  
Ryo Ishikawa ◽  
...  
Keyword(s):  
Titanium Nitride ◽  
Type Structure ◽  
Spinel Type

Transformation of Solid Solution with Spinel-Type Structure Within the Range LiMn2−x(Ni0.33Co0.33Fe0.33)xO4 (0 ≤ x ≤ 2)

2020 ◽  
Vol 41 (6) ◽  
pp. 819-826
Author(s):  
G. D. Nipan ◽  
M. N. Smirnova ◽  
D. Yu Kornilov ◽  
M. A. Kop’eva ◽  
G. E. Nikiforova ◽  
...  
Keyword(s):  
Solid Solution ◽  
Type Structure ◽  
Spinel Type

Spinel-type structure of Co in conditions of HDS catalyst aging

Polyhedron ◽  
1999 ◽  
Vol 18 (5) ◽  
pp. 741-747
Author(s):  
J Kiurski ◽  
D.Z Obadovic ◽  
R Marinkovic-Nedučin ◽  
E Kis
Keyword(s):  
Type Structure ◽  
Spinel Type ◽  
Catalyst Aging

Decomposition Of Co2 To Carbon By H2-Activated Ni(II)- And Co(II)-Bearing Ferrites At 300°C

1994 ◽  
Vol 344 ◽  
Author(s):  
Tatsuya Kodama ◽  
Taizo Sano ◽  
Shig-Ger Chang ◽  
Masamichi Tsuji ◽  
Yutaka Tamaura
Keyword(s):  
Lattice Constant ◽  
Type Structure ◽  
Metal Substitution ◽  
Spinel Type ◽  
Batch System ◽  
Spinel Lattice ◽  
Fe Content ◽  
C Decomposition ◽  
Different Levels

AbstractThe reactivity of the H2-activated Ni(II)- and Co(II)-bearing ferrites with different levels of metal substitution have been studied for CO2 → C decomposition in comparison with that of the H2-activated magnetite. Ni 2+ and Co2+ have been substituted for Fe2+ or Fe3+ in magnetite with the spinel-type structure up to 14 % and 26 % of the mole ratio of Ni2+ and Co2 + to the total Fe content respectively. The reactivity of the Ni(II)- and Co(II)-bearing ferrite increased with the level of metal substitution. Especially, the Ni(II) substitution significantly facilitated the CO2 → C decomposition in a batch system. The rates of H2-activation (reduction) and CO2-decomposition (oxidation) for N(II)-bearing ferrite were studied by a thermogravimeteric analysis. The rates of both H2-activation and CO2-decomposition were much improved in the Ni(II)-bearing ferrite with the Ni(II)/Fetoul mole ratio of 14%. It is considered that the reduced Ni(II) ions which were formed on the surface of the ferrite is very active to facilitate both dissociation reactions of 1) H2 → 2 Hads and 2) CO2→ Cads + 2Oads,. From the change in the lattice constant of the Ni(II)-bearing ferrite during the H2-activation and CO2-decomposition, the oxygens in CO2 were considered to be incorporated into the oxygen deficient spinel lattice of the oxygen deficient Ni(II)-bearing ferrite which had been formed by the H2-activation.

Effect of Mn Doping on the Electronic Structure of ZnGa2O4with Spinel-Type Structure

2001 ◽  
Vol 30 (7) ◽  
pp. 664-665 ◽  
Author(s):  
Moriyasu Nonaka ◽  
Takumi Tanizaki ◽  
Shigenori Matsushima ◽  
Masataka Mizuno ◽  
Chao-Nan Xu
Keyword(s):  
Electronic Structure ◽  
Type Structure ◽  
Spinel Type ◽  
Mn Doping

Determination of the tegengrenite superstructure: another case of tetrahedral Mn3+ in spinel-type minerals?

2015 ◽  
Vol 79 (2) ◽  
pp. 425-436
Author(s):  
Paola Bonazzi ◽  
Luca Bindi
Keyword(s):  
Unit Cell Volume ◽  
Structure Refinement ◽  
Close Packing ◽  
Type Structure ◽  
Cation Ordering ◽  
Spinel Type ◽  
Octahedral Sites ◽  
Tetrahedral Sites ◽  
Scattering Factor

AbstractThe crystal structure of the spinel-related, Sb mineral tegengrenite from the Filipstad district, Värmland, Sweden, has been solved in the space group R3 [a = 16.0285(9), c = 14.8144(8) Å, V = 3296.1(3) Å3, Z = 42] and refined up to R = 0.0484 for 3589 reflections with Fo > 4σ(Fo). Tegengrenite exhibits a rhombohedrally distorted spinel-type structure with cations occupying 1/8 of the tetrahedral (T) and 1/2 of the octahedral (M) interstices of a nearly regular cubic close-packing of oxygen atoms. Due to the cation ordering, which leads to a complex superstructure with a unit-cell volume of 21/4 that of a common spinel, the M and T sites of the spinel-type structure split into ten and six independent sites, respectively. Chemical composition determined by electron microprobe led to the empirical formula Mg1.26Mn0.852+Zn0.04Mn0.193+Al0.01Si0.12Ti0.03Sb0.505+O4, on the assumption that no vacancies occur in the mineral (Σcat = 3.00 and Σcharge = 8.00 per formula unit). Crystal-chemical considerations indicate that octahedra are occupied mainly by Mg, Mn3+ and Sb5+ (+Al, + Ti), whereas tetrahedra are filled mainly by Mn2+ and Mg (+Zn) with Si ordered in a specific site. However, the structure refinement shows a low site-scattering factor for one octahedral site, implying substantial vacancies and a larger overall mean Mn valence than stated above. Long mean distances also suggest some Mn2+ on octahedral sites. Together, these observations necessitate the presence of substantial Mn3+ on tetrahedral sites.

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