[O33] Application of compound-energy formalism to the parabolic growth of solid metal oxides

Previous work, mainly from this research group, is re-visited on electrochemical reduction of solid metal oxides, in the form of compacted powder, in molten CaCl2, aiming at further understanding of the roles of cationic and elemental calcium. The discussion focuses on six aspects: 1.) debate on two mechanisms proposed in the literature, i. e. electro-metallothermic reduction and electro-reduction (or electro-deoxidation), for the electrolytic removal of oxygen from solid metals or metal oxides in molten CaCl2; 2.) novel metallic cavity working electrodes for electrochemical investigations of compacted metal oxide powders in high temperature molten salts assisted by a quartz sealed Ag/AgCl reference electrode (650 ºC- 950 ºC); 3.) influence of elemental calcium on the background current observed during electrolysis of solid metal oxides in molten CaCl2; 4.) electrochemical insertion/ inclusion of cationic calcium into solid metal oxides; 5.) typical features of cyclic voltammetry and chronoamperometry (potentiostatic electrolysis) of metal oxide powders in molten CaCl2; and 6.) some kinetic considerations on the electrolytic removal of oxygen.

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A physical method for investigating defect chemistry in solid metal oxides

APL Materials ◽

10.1063/5.0033891 ◽

2021 ◽

Vol 9 (1) ◽

pp. 011106

Author(s):

Christian Rodenbücher ◽

Carsten Korte ◽

Thorsten Schmitz-Kempen ◽

Sebastian Bette ◽

Kristof Szot

Keyword(s):

Metal Oxides ◽

Physical Method ◽

Defect Chemistry ◽

Solid Metal

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Conversion of Microalgae under Hydrothermal Conditions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.860-863.501 ◽

2013 ◽

Vol 860-863 ◽

pp. 501-505

Author(s):

Ying Ying Zhu ◽

Zeng Xu ◽

Guo Dong Yao ◽

Yun Jun ◽

Fang Ming Jin

Keyword(s):

Acetic Acid ◽

Metal Oxides ◽

Value Added ◽

Green Technology ◽

Solid Metal ◽

Filling Rate ◽

Hydrothermal Conditions ◽

Promising Solution

A new and green technology for converting microalgae to high value-added chemicals with solid metal oxides catalysts under hydrothermal conditions was proposed. The results indicated that ZrO2, among other test catalysts, can prominently boost the production of acetic acid and a highest yield of 24% was achieved at 300 °C for 2 h with a filling rate of 50%. The metal oxides catalyst provided a promising solution to obtain acetic acid from microalgae conversion.

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Stability Criteria for Product Microstructures Formed on Gaseous Reduction of Solid Metal Oxides

Metallurgical and Materials Transactions B ◽

10.1007/s11663-009-9301-8 ◽

2009 ◽

Vol 41 (1) ◽

pp. 19-34 ◽

Cited By ~ 13

Author(s):

Peter C. Hayes

Keyword(s):

Metal Oxides ◽

Solid Metal ◽

Stability Criteria ◽

Gaseous Reduction

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Influences of graphite anode area on electrolysis of solid metal oxides in molten salts

Journal of Solid State Electrochemistry ◽

10.1007/s10008-014-2645-2 ◽

2014 ◽

Vol 18 (12) ◽

pp. 3317-3325 ◽

Cited By ~ 10

Author(s):

Hualin Chen ◽

Xianbo Jin ◽

Linpo Yu ◽

George Z. Chen

Keyword(s):

Metal Oxides ◽

Molten Salts ◽

Solid Metal ◽

Graphite Anode ◽

Anode Area

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Thermal Decomposition of Solid Metal Oxides

Russian Chemical Reviews ◽

10.1070/rc1975v044n05abeh002349 ◽

1975 ◽

Vol 44 (5) ◽

pp. 392-397 ◽

Cited By ~ 8

Author(s):

G V Malinin ◽

Yu M Tolmachev

Keyword(s):

Thermal Decomposition ◽

Metal Oxides ◽

Solid Metal

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HREM Study of electron-induced surface radiation damage in ReO3

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087495 ◽

1991 ◽

Vol 49 ◽

pp. 636-637

Author(s):

R. Ai ◽

H.-J. Fan ◽

L. D. Marks

Keyword(s):

Transition Metal ◽

Metal Ions ◽

Metal Oxides ◽

Electron Irradiation ◽

Transition Metal Oxides ◽

Carbon Film ◽

Transition Metal Ions ◽

Surface Radiation ◽

Valence Transition ◽

Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

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Problems with oxygen analysis in the system MgO-Al2O3-SiO2 with the electron microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132753 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1624-1625

Author(s):

Michel Fialin ◽

Guy Rémond

Keyword(s):

Transition Metal ◽

Metal Oxides ◽

Transition Metal Oxides ◽

Electrostatic Charge ◽

Carbon Layer ◽

Sample Holder ◽

Rock Matrix ◽

Electrical Discharges ◽

Thin Carbon ◽

Beam Instabilities

Oxygen-bearing minerals are generally strong insulators (e.g. silicates), or if not (e.g. transition metal oxides), they are included within a rock matrix which electrically isolates them from the sample holder contacts. In this respect, a thin carbon layer (150 Å in our laboratory) is evaporated on the sections in order to restore the conductivity. For silicates, overestimated oxygen concentrations are usually noted when transition metal oxides are used as standards. These trends corroborate the results of Bastin and Heijligers on MgO, Al2O3 and SiO2. According to our experiments, these errors are independent of the accelerating voltage used (fig.l).Owing to the low density of preexisting defects within the Al2O3 single-crystal, no significant charge buildup occurs under irradiation at low accelerating voltage (< 10keV). As a consequence, neither beam instabilities, due to electrical discharges within the excited volume, nor losses of energy for beam electrons before striking the sample, due to the presence of the electrostatic charge-induced potential, are noted : measurements from both coated and uncoated samples give comparable results which demonstrates that the carbon coating is not the cause of the observed errors.

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