scholarly journals Mathematical modeling of perspective structures of metal oxides

2020 ◽  
Vol 22 (4) ◽  
pp. 268-271
Author(s):  
P. A. Sechenykh
Keyword(s):  
Metal Oxides ◽  
Crystal Lattice ◽  
Structural Characteristics ◽  
Elementary Cell ◽  
Group Symmetry ◽  
Cubic Symmetry ◽  
Lattice Constants ◽  
General Chemical ◽  
Crystalline Metal ◽  
Chemical Formulas

Information about the structure and properties of materials is especially important when working with micro-and nanoscale objects due to the high complexity of their obtaining. This makes it relevant to use computer modeling to predict the required characteristics of materials. Electronic, magnetic, mechanical, and other properties of crystalline substances are determined by their structure-the periodicity of the lattice and the symmetry of the unit cell. This article discusses metal oxides with the general chemical formulas MeO (metals: Ca, Cd, Mg), MeO2 (metals: Hf, Ce, Zr), Me2O3 (metals: Er, Nd, Sc, Mn, Tl) and Me3O4 (using Fe as an example) and a cubic symmetry type crystal lattice — structural types NaCl (rock salt), Fluorite, Bixbyite, Spinel accordingly. The paper describes the model of ion-atomic radii, which is widely used in the modeling of crystalline metal oxides. The application of the annealing simulation algorithm for calculating the metric parameters of the compounds under consideration is shown. The software implementation of the algorithm presented in this paper allows us to determine the coordinates of the atoms that are included in the elementary cell of the crystal lattice, calculate the lattice constant and the density of the packing of atoms in the crystal cell using the specified chemical formula and the space group symmetry. These structural characteristics can be used as input parameters for determining electronic, magnetic, and other properties. The article compares the values of lattice constants obtained as a result of modeling with experimental data.

Nonstoichiometric structures during dehydroxylation of goethite

1989 ◽  
Vol 189 (3-4) ◽  
Author(s):  
Emilia Wolska ◽  
Udo Schwertmann
Keyword(s):  
Crystal Lattice ◽  
Infrared Spectra ◽  
Chemical Formula ◽  
Oh Groups ◽  
X Ray ◽  
Lattice Constants ◽  
General Chemical ◽  
Iron Deficient ◽  
Oxygen Anions ◽  
Integrated Intensities

AbstractThermal dehydration of goethite (The variations of band positions in the infrared spectra and the specific changes in relative integrated intensities of X-ray lines with the increase of dehydration temperature suggested that OH-groups replace oxygen anions in the hematite crystal lattice, while the electroneutrality is preserved by the cation vacancies.Comparison of integrated intensities observed with intensities calculated on this assumption fully confirms that the hematite-like phase is an iron deficient species with a general chemical formulaThe accurate measurements of lattice constants reveal that while the crystallographic

Low-Temperature Liquid Precursors of Crystalline Metal Oxides Assisted by Heterogeneous Photocatalysis

2015 ◽  
Vol 27 (16) ◽  
pp. 2608-2613 ◽  
Author(s):  
Iñigo Bretos ◽  
Ricardo Jiménez ◽  
Dulce Pérez-Mezcua ◽  
Norberto Salazar ◽  
Jesús Ricote ◽  
...  
Keyword(s):  
Low Temperature ◽  
Metal Oxides ◽  
Heterogeneous Photocatalysis ◽  
Liquid Precursors ◽  
Temperature Liquid ◽  
Crystalline Metal

scholarly journals Self-arrangement of nanoparticles toward crystalline metal oxides with high surface areas and tunable 3D mesopores

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Hyung Ik Lee ◽  
Yoon Yun Lee ◽  
Dong-Uk Kang ◽  
Kirim Lee ◽  
Young-Uk Kwon ◽  
...  
Keyword(s):  
Metal Oxides ◽  
High Surface ◽  
Surface Areas ◽  
Crystalline Metal

Role of the Crystal Lattice Constants and Band Structures in the Optoelectronic Spectra of CdGa2S4by DFT Approaches

2017 ◽  
Vol 643 (13) ◽  
pp. 839-849 ◽  
Author(s):  
H. A. Rahnamaye Aliabad ◽  
Hamide Vaezi ◽  
Shiva Basirat ◽  
Iftikhar Ahmad
Keyword(s):  
Crystal Lattice ◽  
Band Structures ◽  
Lattice Constants

Calculating Barriers to Oxygen Penetration on Metal Oxides with the Effective-Medium Theory

1988 ◽  
Vol 141 ◽  
Author(s):  
Maria Ronay ◽  
Peter Nordlander
Keyword(s):  
Metal Oxides ◽  
Electron Density ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Single Atom ◽  
Interstitial Oxygen ◽  
Interatomic Distances ◽  
Medium Theory ◽  
Lattice Constants ◽  
Oxygen Penetration

AbstractWe estimated surface penetration barriers for interstitial oxygen using a simple calculational scheme, the effective-medium theory for a single atom. In this theory the single parameter describing the host is the electron density. Since the electron density depends primarily on the interatomic distances, i.e. the structure of the host, we found that the barrier to oxygen penetration in oxides depends primarily on the structure of the oxide, the closest-packed isotropic oxides with the smallest lattice constants having the highest barriers.

scholarly journals Characterization of The Volcanic Rocks of Mount Sinabung, Simacem Village, Karo Regency, Conducted With XRD, SEM-EDX

2019 ◽  
Vol 1 (1) ◽  
pp. 1-5
Author(s):  
Perdinan Sinuhaji
Keyword(s):  
Crystal Lattice ◽  
Lattice Constant ◽  
Elemental Analysis ◽  
Volcanic Rocks ◽  
Lattice Constants ◽  
Crystal System ◽  
Tetragonal Crystals ◽  
Hexagonal Crystals ◽  
Crystal Lattice Constant

The study of volcanic rocks characterization of Sinabung Volcano erupted on September 15, 2017. The volcanic rocks crystal system was performed with XRD, elemental analysis and microstructure with SEM-EDX. Volcanic rocks contain: Anorthite phase 87,11 (wt%), Triclinic crystal, lattice constant, a = 8.1742 Å, b = 12,844 Å, c = 14,204 Å; Quartz phase 2.26%, Hexagonal crystals, lattice constants, a = 4,799 Å, b = 4,799 Å, c = 5,379 Å; Cristobalite phase 7.72 (wt%), Tetragonal crystals, lattice constants a = 4,970 Å, b = 6,990 Å, c = 6,998 Å; Alunite phase 2.91 (wt%), Hexagonal crystals, lattice constants, a = 6,990 Å, b = 6,990 Å, c = 17,282 Å.

scholarly journals Unravelling the impact of Ta doping on the electronic and structural properties of titania: A combined theoretical and experimental approach

2021 ◽  
Author(s):  
Vignesh Kumaravel ◽  
Maria Barbara Maccioni ◽  
Snehamol Mathew ◽  
Steven Hinder ◽  
John Bartlett ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Structural Characteristics ◽  
Energy Levels ◽  
Average Crystallite Size ◽  
Defect States ◽  
X Ray ◽  
The Impact ◽  
Ta Doping

The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO2. In the present study, the impact of Ta doping on the anatase to rutile transition (ART), structural characteristics, anion and cation vacancy formation were investigated in detail using Density Functional Theory (DFT) and experimental characterisation including, X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS). The average crystallite size of TiO2 decreases with an increase in the Ta concentration. At high temperatures, more oxygen atoms entered the crystal lattice and occupy the vacancies, leading to lattice expansion. Importantly, we find that Ta doping preserved the anatase content of TiO2 up to annealing temperatures of 850 °C which allows anatase stability to be maintained at typical ceramic processing temperatures. The substitution of Ti4+ by the Ta5+ ions increased the electron concentration in the crystal lattice through formation of Ti3+ defect states. Raman studies revealed the formation of new Ta bonds via disturbing the Ti-O-Ti bonds in the crystal lattice. It is concluded that under the oxidising conditions, Ta5+ ions could be enhanced on Ta-TiO2 surface due to the slow diffusion kinetics.

scholarly journals A universal electrochemical lithiation–delithiation method to prepare low-crystalline metal oxides for high-performance hybrid supercapacitors

RSC Advances ◽  
2021 ◽  
Vol 11 (48) ◽  
pp. 30407-30414
Author(s):  
Zhuo-Dong Wu ◽  
De-Jian Chen ◽  
Long Li ◽  
Li-Na Wang
Keyword(s):  
Transition Metal ◽  
Electrochemical Performance ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
High Performance ◽  
Hybrid Supercapacitors ◽  
Electrochemical Lithiation ◽  
Low Crystalline ◽  
Crystalline Metal

The electrochemical performance of transition metal oxides (TMOs) for hybrid supercapacitors has been optimized through various methods in previous reports.

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