Theory of Doping in Studies of Defect Concentration and Transport Properties of Transition Metal Oxides and Sulphides

2015 ◽  
Vol 34 (5) ◽  
Author(s):  
Zbigniew Grzesik
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Oxidation Kinetics ◽  
Defect Formation ◽  
Defect Concentration ◽  
Defect Mobility ◽  
Enthalpy And Entropy ◽  
Kinetics Of

AbstractIn the present paper the theoretical basis and experimental verification of a method, enabling the calculation of defect concentration and their mobility in transition metal oxides and sulphides have been described. The idea of proposed method consists in determination of both these parameters in indirect way, i.e. in studying the influence of aliovalent metallic additions on the oxidation kinetics of a given metal (doping effect). It has been shown that from the results of oxidation kinetics of binary alloys, the enthalpy and entropy of defect formation and their migration can be calculated. These data, in turn, can be used for the calculation of defect concentration and defect mobility in pure, undoped oxides. Such a possibility has been illustrated on the example of nonstoichiometric nickel oxide, Ni

The influence of transition metal oxides on the kinetics of Li2O2oxidation in Li–O2batteries: high activity of chromium oxides

2014 ◽  
Vol 16 (6) ◽  
pp. 2297-2304 ◽  
Author(s):  
Koffi P. C. Yao ◽  
Yi-Chun Lu ◽  
Chibueze V. Amanchukwu ◽  
David G. Kwabi ◽  
Marcel Risch ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
High Activity ◽  
Transition Metal Oxides ◽  
Chromium Oxides ◽  
Kinetics Of

On stability and kinetics of Li-rich transition metal oxides and oxyfluorides

2020 ◽  
Vol 8 (16) ◽  
pp. 7956-7967 ◽  
Author(s):  
Holger Euchner ◽  
Jin Hyun Chang ◽  
Axel Groß
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Kinetics Of

Stability and kinetics of Li-rich transition metal oxides and oxyfluorides are extensively studied by DFT.

scholarly journals Determination of Formation Energies and Phase Diagrams of Transition Metal Oxides with DFT+U

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4303
Author(s):  
Daniel Mutter ◽  
Daniel F. Urban ◽  
Christian Elsässer
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Phase Diagrams ◽  
Transition Metal Oxides ◽  
Density Functional ◽  
Synthesis Process ◽  
Local Exchange ◽  
Electronic Band ◽  
Formation Energies

Knowledge about the formation energies of compounds is essential to derive phase diagrams of multicomponent phases with respect to elemental reservoirs. The determination of formation energies using common (semi-)local exchange-correlation approximations of the density functional theory (DFT) exhibits well-known systematic errors if applied to oxide compounds containing transition metal elements. In this work, we generalize, reevaluate, and discuss a set of approaches proposed and widely applied in the literature to correct for errors arising from the over-binding of the O2 molecule and from correlation effects of electrons in localized transition-metal orbitals. The DFT+U method is exemplarily applied to iron oxide compounds, and a procedure is presented to obtain the U values, which lead to formation energies and electronic band gaps comparable to the experimental values. Using such corrected formation energies, we derive the phase diagrams for LaFeO3, Li5FeO4, and NaFeO2, which are promising materials for energy conversion and storage devices. A scheme is presented to transform the variables of the phase diagrams from the chemical potentials of elemental phases to those of precursor compounds of a solid-state reaction, which represents the experimental synthesis process more appropriately. The discussed workflow of the methods can directly be applied to other transition metal oxides.

Thermogravimetric determination of oxygen in transition metal oxides with a derivatograph

1988 ◽  
Vol 33 (3) ◽  
pp. 883-887 ◽  
Author(s):  
I. A. Konovalova ◽  
V. B. Lazarev ◽  
E. A. Tistchenko ◽  
I. S. Shalplygin
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides

Synergetic Effect of Oxides on Hydrogen Reaction Kinetics of Magnesium Hydride

2007 ◽  
Vol 561-565 ◽  
pp. 1605-1608
Author(s):  
Aep Patah ◽  
Akito Takasaki ◽  
Janusz S. Szmyd
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Reaction Kinetics ◽  
Transition Metal Oxides ◽  
Hydrogen Absorption ◽  
Catalytic Effect ◽  
Synergetic Effect ◽  
Desorption Kinetics ◽  
Absorption Kinetics ◽  
Kinetics Of

The kinetics of hydrogen reaction (absorption and desorption) on the MgH2 have been reported to be improved significantly by addition of transition metal oxides as catalysts. Among the oxides reported previously, Cr2O3 seems to improve hydrogen absorption kinetics and Nb2O5 for desorption kinetics. The catalytic effect of addition of more than one oxide, however, has not been reported yet. We investigated the hydrogen reaction kinetics of ball milled MgH2 powders added with either Cr2O3 or ZnO together with Nb2O5. In absorption reaction, the hydrogen contents reached 6 wt% and 5.3 wt% in 5 min for the powders added with 1 mol% ZnO + 1 mol% Nb2O5 and with 1 mol% Cr2O3 + 1 mol% Nb2O5, respectively. Those powders desorbed hydrogen up to about 4.5 wt% in 20 min. The significant improvement was not expected if one of the oxides was added separately. The combination of two kinds of oxides might play an important role for improvement of reaction kinetics.

Orbital moment determination of simple transition metal oxides using magnetic X-ray diffraction

2001 ◽  
Vol 62 (12) ◽  
pp. 2173-2180 ◽  
Author(s):  
W. Neubeck ◽  
C. Vettier ◽  
F. de Bergevin ◽  
F. Yakhou ◽  
D. Mannix ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
X Ray Diffraction ◽  
Orbital Moment ◽  
X Ray

scholarly journals Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

2015 ◽  
Vol 8 (5) ◽  
pp. 1404-1427 ◽  
Author(s):  
Wesley T. Hong ◽  
Marcel Risch ◽  
Kelsey A. Stoerzinger ◽  
Alexis Grimaud ◽  
Jin Suntivich ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Rational Design ◽  
Artificial Photosynthesis ◽  
Solar Fuels ◽  
Oxide Catalysts ◽  
Perovskite Oxide ◽  
Kinetics Of

The rational design of non-precious transition metal perovskite oxide catalysts holds exceptional promise for understanding and mastering the kinetics of oxygen electrocatalysis instrumental to artificial photosynthesis, solar fuels, fuel cells, electrolyzers, and metal–air batteries.

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