Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Materials Science Poland

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

A facile synthesizing method of vanadium dioxide by pyrolyzing ammonium metavanadate

Qi J., Ning G., Hua R., Tian M., Liu S.

Materials Science Poland

2012

Vol. 30, No. 2

151--157

A facile process was developed for synthesizing vanadium dioxide (VO2) by pyrolyzing ammonium metavanadate (NH4VO3) in nitrogen flow. The process was designed on the base of thermodynamic modeling of chemical reaction and thermal analyzing of NH4VO3 pyrogenation in N2 gas, and optimized by experiments. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were applied to characterizing the product VO2. Thermo-gravimetric analysis (TG) and DSC were used for analyzing the process of NH4VO3 pyrogenation. The experimental results indicated that VO2 microcrystal particles were successfully synthesized. The product VO2 presents two kinds of micro morphologies, torispherical and pentagonal prism. The phase transition mainly takes place at 338.4 K and 341.9 K. The average enthalpy of the phase transition is 28.82 J/g.

Synthesis and characterization of V2O3 microcrystal particles controlled by thermodynamic parameters

Qi J., Ning G., Zhao Y., Tian M., Xu Y., Hai H.

Materials Science Poland

2010

Vol. 28, No. 2

535--543

A facile process is developed for the synthesis of pure vanadium(III) oxide by thermal reduction of vanadium pentoxide (V2O5) in ammonia gas. The process of thermal reduction of V2O5 was optimized by experiments and by modeling of thermodynamic parameters. The obtained V2O3 was characterized by X-ray diffraction, X-ray photoelectron spectrometry, scanning electron microscopy and thermogravimetric analysis. The experimental results indicated that crystal particles of pure V2O3 were successfully synthesized within a short reaction period of 1 h and at a relatively low temperature of 903 K. The content of V2O3 in the product sample higher than 99 wt. %. The grain size of V2O3 ranged from several hundred nanometers to several micrometers. The morphologies of the V2O3 particles were micrometer layers in nanometer sheet structure.