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| 2. |
- Al-Hinai, A. T., et al.
(författare)
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Application of Eh-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media
- 2014
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Ingår i: Materials research bulletin. - : Elsevier. - 0025-5408 .- 1873-4227. ; 49:1, s. 645-650
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Tidskriftsartikel (refereegranskat)abstract
- Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO3) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn2+ and Sn4+ was controlled for the precipitation in a one pot synthesis step at room temperature (25 degrees C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn2+ + Sn4+) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization olnano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO3.3H(2)O form.
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| 3. |
- Al-Hinai, M. H., et al.
(författare)
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Phase transformation behavior of zinc metastannates obtained by aqueous precipitation at different temperatures
- 2014
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Ingår i: Journal of Materials Science. - : Springer-Verlag New York. - 0022-2461 .- 1573-4803. ; 49:20, s. 7282-7289
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Tidskriftsartikel (refereegranskat)abstract
- Phase transformation studies in ZnO-SnO2 system from zinc metastannate (ZnSnO3) to zinc orthostannate (Zn2SnO4) with annealing temperature are reported. Non-centrosymmetric oxides show unique symmetry dependent and spontaneous polarization properties, which are technologically important. ZnSnO3 particles were synthesized by a simple aqueous synthesis at low temperatures designed with the assistance of potential-pH diagrams. ZnSnO3 particles synthesized at 4 A degrees C are more porous losing the ilmenite structure upon annealing at 200 A degrees C, while the other samples prepared at higher temperatures (25-65 A degrees C) becomes amorphous at 300 A degrees C. The phase transformation into the inverse spinel orthostannate phase occurs around 750 A degrees C in all the samples.
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| 4. |
- Bora, T., et al.
(författare)
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Phase Transformation of Metastable ZnSnO3 Upon Thermal Decomposition by In-Situ Temperature-Dependent Raman Spectroscopy
- 2015
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Ingår i: Journal of The American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916.
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Tidskriftsartikel (refereegranskat)abstract
- Temperature-dependent in-situ Raman spectroscopy is used to investigate the phase transformation of zinc metastannate (ZnSnO3) to zinc orthostannate (Zn2SnO4) induced upon annealing in the ambient. ZnSnO3 microcubes (MCs) were synthesized at room temperature using a simple aqueous synthesis process, followed by characterization using electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Annealing of the ZnSnO3 MCs was carried out up to 1000°C, while recording the Raman spectra in-situ at regular intervals. Phase transformation from metastannate to orthostannate was found to begin around 500°C with an activation energy of ~0.965 eV followed by the recrystallization into the inverse spinel orthostannate phase at ~750°C. Results from this study provide detailed understanding of the phase transformation behavior of perovskite ZnSnO3 to inverse spinel Zn2SnO4 upon thermal annealing.
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| 5. |
- Najam Khan, M., et al.
(författare)
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Visible light photocatalysis of mixed phase zinc stannate/zinc oxide nanostructures precipitated at room temperature in aqueous media
- 2014
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:6, s. 8743-8752
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous synthesis was used to obtain zinc stannate (ZTO) nanoparticles by precipitation at room temperature. Pourbaix diagrams were employed to formulate the precipitation reactions and synthesis process. Solution pH was controlled during the synthesis process as a major variable. The synthesized ZTO particles showed good photocatalytic activity under UV light irradiation. In order to improve visible light photocatalytic activity of ZTO nanoparticles, mixed phase zinc stannate/zinc oxide (ZnO) composites were prepared by co-precipitation at room temperature. Effects of precursor concentrations on the size and morphology of the obtained particles are reported. The composite ZTO/ZnO showed better photodegradation under visible light irradiation compared to ZTO and ZnO nanoparticles with methylene blue (MB) as a test chemical contaminant. Experiments were designed to elaborate on the active species for photocatalytic degradation of the dye and are reported here. Benzoquinone (BQ) was found to be the most effective scavenger, reducing the photodegradation considerably, indicating that O2-• plays a major role in MB degradation since 50% reduction in photocatalytic activity was observed.
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