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.

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.

Interaction of perovskite-like compounds based on transition-metal oxides with gas phase at T = 200–400°C

2014 ◽  
Vol 115 (6) ◽  
pp. 547-556 ◽  
Author(s):  
N. A. Zyuzeva ◽  
I. B. Bobylev ◽  
S. V. Naumov ◽  
E. P. Romanov
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Gas Phase ◽  
Transition Metal Oxides

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.

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