scholarly journals KPFM work function characterization of ongoing reduction and oxidation of transition metal oxide crystals on examples of SrTiO3 and TiO nanowires

2019 ◽  
Author(s):  
Dominik Wrana ◽  
Karol Cieślik ◽  
Wojciech Bełza ◽  
Christian Rodenbücher ◽  
Krzysztof Szot ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Work Function ◽  
Transition Metal Oxides ◽  
Operating Conditions ◽  
Lateral Resolution ◽  
Force Microscopy ◽  
Function Characterization ◽  
Reduction And Oxidation

Controlling the work function of transition metal oxides is of key importance towards future energy production and storage. As majority of applications comprise the use of heterostructures, the most suitable experimental technique is Kelvin Probe Force Microscopy, providing excellent energetic and lateral resolution. In this paper we demonstrate the possibility of the precise work function characterization using the example of artificially formed crystalline titanium monoxide TiO nanowires on strontium titanate SrTiO3 surfaces providing a sharp atomic interface. The measured value of 3.31(21) eV is the first experimental work function evidence for a cubic TiO phase, being additionally subjected to significant variations among different crystallographic facets. Despite the remarkable height of the formed TiO nanowires, FM-KPFM proved to be able to achieve high lateral resolution of 15 nm, which is close to the topographical limits. In this study we show also the unique possibility of obtaining conductivity and work function maps on the same area, by combining contact and non-contact atomic force microscopy. As most of real applications require ambient operating conditions, we have additionally checked the impact of air venting on the work function of the TiO/SrTiO3(100) heterostructure, proving the surface re-oxidation occurs and results in  work function increases of 0.9 eV and 0.6 eV for SrTiO3 and TiO, respectively. In addition, the influence of physisorbed species was estimated to contribute 0.4 eV and 0.2 eV to the work function of both structures. The presented method of the KPFM (and LC-AFM) employment for the work function characterization of transition metal oxides may help to understand the reduction and oxidation impact on electronic properties, which is of high importance towards the development of effective sensing and catalytic devices.

scholarly journals Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

2019 ◽  
Vol 10 ◽  
pp. 1596-1607
Author(s):  
Dominik Wrana ◽  
Karol Cieślik ◽  
Wojciech Belza ◽  
Christian Rodenbücher ◽  
Krzysztof Szot ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Work Function ◽  
Transition Metal Oxides ◽  
Lateral Resolution ◽  
Kelvin Probe ◽  
Force Microscopy ◽  
Reduction And Oxidation ◽  
The Impact

Controlling the work function of transition metal oxides is of key importance with regard to future energy production and storage. As the majority of applications involve the use of heterostructures, the most suitable characterization technique is Kelvin probe force microscopy (KPFM), which provides excellent energetic and lateral resolution. In this paper, we demonstrate precise characterization of the work function using the example of artificially formed crystalline titanium monoxide (TiO) nanowires on strontium titanate (SrTiO3) surfaces, providing a sharp atomic interface. The measured value of 3.31(21) eV is the first experimental work function evidence for a cubic TiO phase, where significant variations among the different crystallographic facets were also observed. Despite the remarkable height of the TiO nanowires, KPFM was implemented to achieve a high lateral resolution of 15 nm, which is close to the topographical limit. In this study, we also show the unique possibility of obtaining work function and conductivity maps on the same area by combining noncontact and contact modes of atomic force microscopy (AFM). As most of the real applications require ambient operating conditions, we have additionally checked the impact of air venting on the work function of the TiO/SrTiO3(100) heterostructure, proving that surface reoxidation occurs and results in a work function increase of 0.9 eV and 0.6 eV for SrTiO3 and TiO, respectively. Additionally, the influence of adsorbed surface species was estimated to contribute 0.4 eV and 0.2 eV to the work function of both structures. The presented method employing KPFM and local conductivity AFM for the characterization of the work function of transition metal oxides may help in understanding the impact of reduction and oxidation on electronic properties, which is of high importance in the development of effective sensing and catalytic devices.

Preparation and Characterization of Several Conducting Transition Metal Oxides

1989 ◽  
Vol 156 ◽  
Author(s):  
Aaron Wold ◽  
Kirby Dwight
Keyword(s):  
Transition Metal ◽  
Single Crystal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Structure Property ◽  
Metallic Behavior ◽  
Structure Property Relationships ◽  
Conduction Bands ◽  
Metal Metal

ABSTRACTThe structure-property relationships of several conducting transition metal oxides, as well as their preparative methods, are presented in this paper. The importance of preparing homogeneous phases with precisely known stoichiometry is emphasized. A comparison is also made of the various techniques used to prepare both polycrystalline and single crystal samples. For transition metal oxides, the metallic properties are discussed either in terms of metal-metal distances which are short enough to result in metallic behavior, or in terms of the formation of a П* conduction band resulting from covalent metal-oxygen interactions. Metallic behavior is observed when the conduction bands are populated with either electrons or holes. The concentration of these carriers can be affected by either cation or anion substitutions. The discussion in this presentation will be limited to the elements Re, Ti, V, Cr, Mo, and Cu.

Characterization of Transition-Metal Oxides Promoted with Oxoanions by Means of Test Reactions

2005 ◽  
Vol 44 (6) ◽  
pp. 1716-1721 ◽  
Author(s):  
Viviana M. Benítez ◽  
Juan C. Yori ◽  
Carlos R. Vera ◽  
Carlos L. Pieck ◽  
Javier M. Grau ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Test Reactions

On the Electroanalytical Characterization of LixCoO2, LixNiO2 and LiMn2O4 (Spinel) Electrodes in Repeated Lithium Intercalation-Deintercalation Processes

1997 ◽  
Vol 496 ◽  
Author(s):  
D. Aurbach ◽  
M. D. Levi ◽  
E. Levi ◽  
B. Markovsky ◽  
G. Salitra ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Failure Mechanisms ◽  
Lithium Intercalation ◽  
Li Ion Batteries ◽  
Fast Scan Cyclic Voltammetry ◽  
Limn2o4 Spinel ◽  
Li Ion

ABSTRACTThis paper reports on electroanalytical studies of the intercalation-deintercalation of lithium into lithiated transition metal oxides which are used as cathodes for Li ion batteries. These include LixCoO2 LixNiO2 and LixMn2O4 spinel. The basic electroanalytical response of these systems in LiAsF6 1M/EC-DMC solutions was obtained from the simultaneous use of slow and fast scan cyclic voltammetry (SSCV), potentiostatic intermittent titration (PITT) (from which D vs. E was calculated), and impedance spectroscopy (EIS). Surface sensitive FTIR spectroscopy and XRD were also used for surface and 3D characterization, respectively. A large and important denominator was found in the electrochemical behavior of lithium intercalation-deintercalation into these transition metal oxides and graphite. The use of the electroanalytical response of these systems as a tool for the study of stabilization and failure mechanisms of these materials as cathodes in rechargeable Li batteries is demonstrated and discussed.

Onset Conditions for Gas Phase Reaction and Nucleation in the CVD of Transition Metal Oxides

1991 ◽  
Vol 250 ◽  
Author(s):  
J. Collins ◽  
D. E. Rosner ◽  
J. Castillo
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Gas Phase ◽  
Transition Metal Oxides ◽  
Film Theory ◽  
Operating Conditions ◽  
Particle Nucleation ◽  
Phase Reaction ◽  
Homogeneous Reaction ◽  
Gas Phase Reaction

AbstractA combined experimental/theoretical study is presented of the onset conditions for gas phase reaction and particle nucleation in hot substrate/cold gas CVD of transition metal oxides. Homogeneous reaction onset conditions are predicted using a simple high activation energy reacting gas film theory. Experimental tests of the basic theory are underway using an axisymmetric impinging jet CVD reactor. No “vapor phase ignition” has yet been observed in the TiCl4/O2 system under accessible operating conditions (below substrate temperature Tw=1700 K) and further experiments are planned using more reactive feed materials. The goal of this research is to provide CVD reactor design and operation guidelines for achieving acceptable deposit microstructures at the maximum deposition rate while simultaneously avoiding homogeneous reaction/nucleation and diffusional limitations.

Low Temperature Synthesis of Lamellar Transition Metal Oxides Containing Surfactant Ions

1996 ◽  
Vol 457 ◽  
Author(s):  
Gerald G. Janauer ◽  
Rongji Chen ◽  
Arthur D. Dobley ◽  
Peter Y. Zavalij ◽  
M. Stanley Whittingham
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Layered Compounds ◽  
Vanadium Compound ◽  
Low Temperature Synthesis ◽  
X Ray ◽  
Mechanisms Of Formation

ABSTRACTRecently there has been much interest in reacting vanadium oxides hydrothermally with cationic surfactants to form novel layered compounds. A series of new transition metal oxides, however, has also been formed at or near room temperature in open containers. Synthesis, characterization, and proposed mechanisms of formation are the focus of this work. Low temperature reactions of vanadium pentoxide and ammonium (DTA) transition metal oxides with long chain amine surfactants, such as dodecyltrimethylammonium bromide yielded interesting new products many of which are layered phases. DTA4H2V10O28•8H2O, a layered highly crystalline phase, is the first such phase for which a single crystal X-ray structure has been determined. The unit cell for this material was found to be triclinic with space group P 1 and dimensions a=9.895(1)Å, b=11.596(1)Å, c=21.924(1)Å, α=95.153(2)°, β=93.778(1)°, and γ= 101.360(1)°. Additionally, we synthesized a dichromate phase and a manganese chloride layered phase, with interlayer spacings of 26.8Å, and 28.7Å respectively. The structure, composition, and synthesis of the vanadium compound are described, as well as the synthesis and preliminary characterization of the new chromium and manganese materials.

scholarly journals Enhanced aquathermolysis of extra-heavy oil by application of transition metal oxides submicro-particles in relation to steam injection processes

2021 ◽  
Vol 11 (11) ◽  
pp. 4019-4028
Author(s):  
Xian Zhang ◽  
Hongchang Che ◽  
Yongjian Liu
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Heavy Oil ◽  
Transition Metal Oxides ◽  
Steam Injection ◽  
Operating Conditions ◽  
Viscosity Reduction ◽  
Optimum Operating ◽  
Catalytic Aquathermolysis ◽  
Optimum Reaction

AbstractIn order to investigate the catalytic effects of transition metal oxides submicro-particles on aquathermolysis of Liaohe extra-heavy crude oil, the catalysts NiO, α·Fe2O3 and Co3O4 are used and evaluated during the experiments. The optimum mass fraction of the catalyst and water was determined to be 5.0 wt% and 30 wt%, respectively. The optimum reaction time for aquathermolysis was 24 h, and the optimum reaction temperature was 240 °C. The analysis results showed the heavy oil was upgraded dramatically by addition of the catalysts based upon viscosity reduction, saturate/aromatics/resins/asphaltenes analyses, elemental analysis, Fourier transform infrared spectroscopy and gas chromatography. All results show the heavy oil is in situ updated dramatically by catalytic aquathermolysis under the optimum operating conditions. A five-lump model is proposed for estimating kinetic parameters of aquathermolysis and agrees well with the experimental data.

Sign in / Sign up

Export Citation Format

Share Document