HREM Study of electron-induced surface radiation damage in ReO3

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.

scholarly journals Stability profiles of transition metal oxides in the oxygen evolution reaction in alkaline medium

2019 ◽  
Vol 7 (45) ◽  
pp. 25865-25877 ◽  
Author(s):  
Aliki Moysiadou ◽  
Xile Hu
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Oxygen Evolution ◽  
Alkaline Medium ◽  
Transition Metal Oxides ◽  
Oxygen Evolution Reaction ◽  
Electrolyte Solutions ◽  
Compositional Changes ◽  
Dynamic Exchange

Metal oxides undergo compositional changes due to a dynamic exchange of metal ions with the electrolyte solutions during the oxygen evolution reaction.

Layered Tungsten Oxide-Based Hybrid Materials Incorporating Transition Metal Ions

2004 ◽  
Vol 847 ◽  
Author(s):  
Bridget Ingham ◽  
S. V. Chong ◽  
Jeff L. Tallon
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Tungsten Oxide ◽  
Hybrid Materials ◽  
Transition Metal Oxides ◽  
Metal Ion ◽  
Interlayer Spacing ◽  
Transition Metal Ions ◽  
Ferromagnetic Transition ◽  
Inorganic Framework

ABSTRACTLayered organic-inorganic hybrid materials based on tungsten oxide as the inorganic framework have been synthesised to include transition metal ions. The resulting materials have been characterised using a number of techniques. X-ray diffraction shows an interlayer expansion with increasing alkyl length. Infrared vibrational spectra of manganese tungstate compounds indicate the organic amine molecules are neutrally charged, and the inorganic framework is unaltered as one varies the organic intercalate. The magnetic behaviour of the materials has also been explored using a SQUID magnetometer. In the manganese tungstate hybrids an antiferromagnetic (AF) transition is observed, which decreases in temperature as the inorganic interlayer spacing is increased. A nickel tungstate hybrid sample, on the other hand, displays a ferromagnetic transition, which we attribute to a canted AF phase below 15 K. In all cases studied, the behaviour can be mapped to an effective moment (Peff) per transition metal ion, which agrees well with theoretical and literature values for other transition metal oxides.

Epitaxial Relationships in Esd Processes on Oxide Surfaces

1988 ◽  
Vol 129 ◽  
Author(s):  
M.R. Mccartney ◽  
David J. Smith
Keyword(s):  
Electron Microscope ◽  
Transition Metal ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Structural Features ◽  
Epitaxial Relationship ◽  
Crystalline Layer ◽  
Electron Stimulated Desorption ◽  
Intense Electron

ABSTRACTDuring intense electron irradiation inside the electron microscope, the electron—stimulated desorption of oxygen from the surfaces of several maximally—valent transition—metal oxides (TiO2, V2O5, Nb2 O5 and WO3) has been observed [1]. The irradiatedsurfaces become covered with a crystalline layer of the corresponding monoxide phase. These reduced phases, which are all based on cubic structures and have metallic conductivity, grow with a well— defined epitaxial relationship with the bulk oxide. Computer—drawn models of the crystal structures have been used to study the atomic arrangements implied by the epitaxial relationship, and certain structural features were found to be common to the oxides studied.

scholarly journals Boosting Electrochemical Performance of Hematite Nanorods via Quenching-Induced Alkaline Earth Metal Ion Doping

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1102
Author(s):  
Qin Chen ◽  
Yanan Chong ◽  
Mumin Rao ◽  
Ming Su ◽  
Yongcai Qiu
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Electrochemical Performances ◽  
Alkaline Earth Metal Ions ◽  
Ion Doping

Ion doping in transition metal oxides is always considered to be one of the most effective methods to obtain high-performance electrochemical supercapacitors because of the introduction of defective surfaces as well as the enhancement of electrical conductivity. Inspired by the smelting process, an ancient method, quenching is introduced for doping metal ions into transition metal oxides with intriguing physicochemical properties. Herein, as a proof of concept, α-Fe2O3 nanorods grown on carbon cloths (α-Fe2O3@CC) heated at 400 °C are rapidly put into different aqueous solutions of alkaline earth metal salts at 4 °C to obtain electrodes doped with different alkaline earth metal ions (M-Fe2O3@CC). Among them, Sr-Fe2O3@CC shows the best electrochemical capacitance, reaching 77.81 mF cm−2 at the current of 0.5 mA cm−2, which is 2.5 times that of α-Fe2O3@CC. The results demonstrate that quenching is a feasible new idea for improving the electrochemical performances of nanostructured materials.

Shedding Light on the Usefulness of Chemical Reaction Between Urea and Transition Metal Ions to Produce Metal Oxides in Nanoscale: Part Three

2016 ◽  
Vol 13 (8) ◽  
pp. 5543-5549 ◽  
Author(s):  
Omar B Ibrahim ◽  
Moamen S Refat ◽  
Abdel Majid A Adam ◽  
Mohamed A Al-Omar ◽  
Ahmed M Naglah
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Chemical Reaction ◽  
Transition Metal Ions

Oriented external electric fields as mimics for probing the role of metal ions and ligands in the thermal gas-phase activation of methane

2018 ◽  
Vol 47 (43) ◽  
pp. 15271-15277 ◽  
Author(s):  
Caiyun Geng ◽  
Jilai Li ◽  
Maria Schlangen ◽  
Sason Shaik ◽  
Xiaoyan Sun ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Gas Phase ◽  
Electric Fields ◽  
Transition Metal Ions ◽  
Simple Metal ◽  
External Electric Fields

Unusual, if not unprecedented, effects of transition-metal ions and ligands are discovered when simple metal oxides or carbides activate methane in the gas phase in manners reminiscent of oriented external electric fields.

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

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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