Effects of Calcining Conditions on the Structures of Co-Doped VO2(M) Nanopowders

2010 ◽  
Vol 152-153 ◽  
pp. 683-686
Author(s):  
Ai Hong Bi ◽  
Jin Hua Zhu
Keyword(s):  
Thermal Decomposition ◽  
Grain Size ◽  
Oxalic Acid ◽  
Vanadium Pentoxide ◽  
Lattice Parameters ◽  
Step Method ◽  
Ammonium Tungstate ◽  
Diffraction Peaks ◽  
Co Doped

W and Mo co-doped VO2(M) nanopowders were synthesized by thermal decomposition via two-step method using oxalic acid as reduction acid, vanadium pentoxide as vanadium source, ammonium tungstate and ammonium molybdates as doped sources. The effects of the calcining temperatures and calcining times on the intensities of the diffraction peaks, the grain size and lattice parameters were investigated by means of XRD.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

Chemical Vapor Deposition of Binary Metal Germanides

1990 ◽  
Vol 187 ◽  
Author(s):  
M.J. Hampden-Smith ◽  
J. Garvey ◽  
D. Lei ◽  
J.C. Huffman
Keyword(s):  
Thermal Decomposition ◽  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Transition Metal ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Solution Model ◽  
Binary Metal ◽  
Decomposition Experiments

AbstractA series of transition metal substituted germacyclopent-3-ene compounds containing transition metal-germanium bonds have been prepared with supporting ligands which are designed to be easily removed either thermally or photochemically. In solution, model thermal decomposition experiments show that either the geramanium or the transition metal substituents may be removed, depending on the nature of the metal. Preliminary hot-wall CVD experiments using manganese and cobalt derivatives result in films with small grain size.

The thermal decomposition of chrysotile

1977 ◽  
Vol 41 (320) ◽  
pp. 453-459 ◽  
Author(s):  
C. J. Martin
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Thermal Treatment ◽  
High Temperatures ◽  
Lattice Parameters ◽  
Atomic Arrangement ◽  
Observable Change ◽  
Infra Red ◽  
Magnesium Silicates

SummaryThe decomposition of chrysotile fibres heated in air has been studied in the range 100–1400°C by electron microscopy and infra-red absorption. The first observable change in the structure occurred at 580°C, where cavities started to open up between the (001) layers of chrysotile as the fibres were dehydrated, giving rise to strong low-angle diffraction. There was no evidence of any structure in the remaining material but some degree of the original atomic arrangement was preserved for the magnesium silicates, forsterite, and enstatite, later developed in certain preferred orientations. The manner of this crystallization was determined by the thermal treatment, for in samples held between 600°C and 800°C forsterite developed slowly with little further disruption of the fibre while above 800°C the remaining amorphous areas rapidly recrystallized to a mixture of forsterite and enstatite. It is suggested that the mechanisms described by other investigators to explain the development of forsterite in preferred orientations may serve simply to nucleate the crystallization and a similar mechanism to account for the nucleation of the enstatite crystallization is considered. At high temperatures a possible doubling of some of the lattice parameters of the silicates was observed.

Synthesis and Dispersity of YBCO Powder Produced by Oxalic Acid Precipitation Method

2015 ◽  
Vol 645-646 ◽  
pp. 145-150 ◽  
Author(s):  
Ai Qin Wang ◽  
Hui Hui Han ◽  
Min Li ◽  
Jing Pei Xie ◽  
Qing Jie Wu ◽  
...  
Keyword(s):  
Grain Size ◽  
Oxalic Acid ◽  
Technological Parameter ◽  
Oxalic Acid Solution ◽  
Acid Precipitation ◽  
Precipitation Method ◽  
Test Results ◽  
Ph Values ◽  
Mean Grain Size ◽  
The Mean

The YBCO powder was prepared by oxalic acid precipitation method and consequent annealing. The correlation between pH values of oxalic acid solution and the precipitation percentage of precursors were analysed based on thermodynamics analysis. The differential scanning calorimetryanalysis (DSC) was used to confirm the synthetic technological parameter. The phases of powder in each process were investigated by XRD. The microstructures of each powder were tested by SEM and TEM. The mean grain size was calculated by the scherrer’s equation. The test results indicated that the YBCO powder with high purity, less impurities, smaller particle, but severe agglomeration, was Y123 when annealing at 900°C. However, adding dispersants could effectively solve the severe agglomeration. The size of YBCO particles was nanosized and coincided with the calculation.

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