scholarly journals Design of Multifunctional Titania-Based Photocatalysts by Controlled Redox Reactions

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 758 ◽  
Author(s):  
Diogo Lopes ◽  
Ana Luísa Daniel-da-Silva ◽  
Artur R. Sarabando ◽  
Blanca I. Arias-Serrano ◽  
Elena Rodríguez-Aguado ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Phase Composition ◽  
Lower Surface ◽  
Solid State Route ◽  
Co Activation ◽  
Shell Particles ◽  
Oxidation In Air ◽  
Microstructural Studies ◽  
Conventional Solid State Route ◽  
Apparent Reaction Rate

This work aims at the preparation of multifunctional titania-based photocatalysts with inherent capabilities for thermal co-activation and stabilisation of anatase polymorph, by designing the phase composition and microstructure of rutile-silicon carbide mixture. The processing involved a conventional solid state route, including partial pre-reduction of rutile by SiC in inert Ar atmosphere, followed by post-oxidation in air. The impacts of processing conditions on the phase composition and photocatalytic activity were evaluated using Taguchi planning. The XRD studies confirmed the presence of rutile/anatase mixtures in the post-oxidised samples. The results emphasise that pre-reduction and post-oxidation temperatures are critical in defining the phase composition, while post-oxidation time is relevant for the photocatalytic performance. Microstructural studies revealed the formation of core-shell particles, which can suppress the photocatalytic activity. The highest apparent reaction rate of the photodegradation of methylene blue was observed for the sample pre-reduced in Ar at 1300 °C for 5 h and then calcined in air at 400 °C for 25 h. Though its performance was ~1.6-times lower than that for the same amount of nanostructured industrial P25 photocatalyst, it was achieved in the material possessing 2–3 times lower surface area and containing ~50 mol% of SiO2 and SiC, thus demonstrating excellent prospects for further improvements.

scholarly journals Unexpected Link between the Template Purification Solvent and the Structure of Titanium Dioxide Hollow Spheres

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Tamás Gyulavári ◽  
Kata Kovács ◽  
Klára Magyari ◽  
Kornélia Baán ◽  
Anna Szabó ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Phase Composition ◽  
Anatase Phase ◽  
Hollow Spheres ◽  
Rutile Phase ◽  
Carbon Sphere ◽  
Carbon Spheres ◽  
Carbonate Species ◽  
Determining Factor

Carbon spheres were applied as templates to synthesize titanium dioxide hollow spheres. The templates were purified with either ethanol or acetone, and the effects of this treatment on the properties of the resulting titania were investigated. The photocatalytic activity of the catalysts was measured via the decomposition of phenol model pollutant under visible light irradiation. It was found that the solvent used for the purification of the carbon spheres had a surprisingly large impact on the crystal phase composition, morphology, and photocatalytic activity. Using ethanol resulted in a predominantly rutile phase titanium dioxide with regular morphology and higher photocatalytic activity (r0,phenol = 3.9 × 10−9 M∙s−1) than that containing mainly anatase phase prepared using acetone (r0,phenol = 1.2 × 10−9 M∙s−1), surpassing the photocatalytic activity of all investigated references. Based on infrared spectroscopy measurements, it was found that the carbon sphere templates had different surface properties that could result in the appearance of carbonate species in the titania lattice. The presence or absence of these species was found to be the determining factor in the development of the titania’s properties.

Dielectric and Magnetic Properties of BaTiO3/NiFe2O4 Composites

2007 ◽  
Vol 336-338 ◽  
pp. 377-380 ◽  
Author(s):  
Jian Hong Shen ◽  
Ji Zhou ◽  
Xue Min Cui ◽  
Yue Hui Wang
Keyword(s):  
Dielectric Constant ◽  
Magnetic Properties ◽  
Solid State ◽  
Spinel Structure ◽  
Initial Permeability ◽  
Solid State Route ◽  
Permittivity And Permeability ◽  
Xrd Studies ◽  
Two Phases ◽  
Conventional Solid State Route

A series of ferrroelectric-ferromagnetic composites were synthesized from BaTiO3 and NiFe2O4 ferrite by conventional solid-state route. XRD studies indicated that the composites comprised of only two phases, BaTiO3 phase with perovskite structure and NiFe2O4 phase with spinel structure. Frequency dependence of permittivity and permeability were also measured. Experimental results showed that the dielectric constant and initial permeability of these composites could be tunable by varying the composition of composites. Thus, these composites can be used for multilayer chips EMI filters.

Effect of Sintering Behavior on Microwave Properties of (Ca0.8Sr0.2)ZrO3 Ceramics for Resonators

2014 ◽  
Vol 787 ◽  
pp. 338-341
Author(s):  
Cheng Hsing Hsu ◽  
Chia Hao Chang ◽  
Wen Shiush Chen ◽  
Jenn Sen Lin ◽  
Chun Hung Lai
Keyword(s):  
Dielectric Constant ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Passive Components ◽  
Suitable Candidate ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Microwave Ceramic ◽  
Conventional Solid State Route

Microwave dielectric properties and microstructures of (Ca0.8Sr0.2)ZrO3 ceramics prepared by the conventional solid-state route have been studied. The values of the dielectric constant (εr) were 22-26. The Q×f values of 10400–11500 GHz were obtained when the sintering temperatures were in the range of 1400–1490°C. The temperature coefficient of the resonant frequency τf was not sensitive to the sintering temperature. The εr value of 26, the Q×f value of 11500 GHz, and the τf value of-9 ppm/°C were obtained for (Ca0.8Sr0.2)ZrO3 ceramics sintering at 1490°C. The ceramic, (Ca0.8Sr0.2)ZrO3 is proposed as a suitable candidate material for application in highly selective microwave ceramic passive components.

scholarly journals Quantitative XRD characterisation and gas-phase photocatalytic activity testing for visible-light (indoor applications) of KRONOClean 7000®

RSC Advances ◽  
2015 ◽  
Vol 5 (124) ◽  
pp. 102911-102918 ◽  
Author(s):  
D. M. Tobaldi ◽  
M. P. Seabra ◽  
G. Otero-Irurueta ◽  
Y. R. de Miguel ◽  
R. J. Ball ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Phase Composition ◽  
Visible Light ◽  
Gas Phase ◽  
Amorphous Content ◽  
First Time

Carbon-modified commercial anatase (KRONOClean 7000®) was quantitatively characterised with XRD for the first time – full phase composition (both crystalline and amorphous content) and microstructure.

Performance of Gd-Ba-Cu-O Superconductor Bulks with Ultrafine Gd2BaCuO5 Powders Prepared by Low-Temperature Combustion Synthesis

2007 ◽  
Vol 546-549 ◽  
pp. 2111-2114
Author(s):  
X.H. Ma ◽  
Xin Tai Su ◽  
Qing Zhi Yan ◽  
Y.L. Jiao ◽  
L. Xiao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Combustion Synthesis ◽  
Low Temperature Combustion ◽  
Solid State Route ◽  
Morphology And Structure ◽  
Temperature Combustion ◽  
Conventional Solid State Route ◽  
Scanning Electron

This paper describes the details on synthesizing nanocrystalline Gd2BaCuO5 (Gd211) using low-temperature combustion synthesis(LCS). The morphology and structure of the powders are characterized by field emission scanning electron microscopy (FESEM) and XRD. The size of obtained powders by this method calcined at 800 C is about 100nm, which is much smaller than the powders synthesizing by conventional solid state route. Besides, the Gd211 powders synthesizing by LCS have a low calcination temperature with a high-purity. The microstructure of melt-textured samples is also observed by FESEM, the result shows that the size of Gd211 particles trapped in GdBa2Cu3O7 (Gd123) matrix could be refined by using ultrafine Gd211 powder as a precursor. The refined Gd211 particles with a good distribution resulted in the improvement of Jc values in this system.

Influence of pH of sol-gel solution on phase composition and photocatalytic activity of TiO 2 under UV and visible light

2016 ◽  
Vol 84 ◽  
pp. 152-161 ◽  
Author(s):  
B. Tryba ◽  
M. Tygielska ◽  
C. Colbeau-Justin ◽  
E. Kusiak-Nejman ◽  
J. Kapica-Kozar ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Phase Composition ◽  
Visible Light ◽  
Sol Gel ◽  
Influence Of Ph

Influence of TiO2 phase composition on the photocatalytic activity of TiO2/MWCNT composites prepared by combined sol–gel/hydrothermal method

2016 ◽  
Vol 414 ◽  
pp. 140-147 ◽  
Author(s):  
Balázs Réti ◽  
Zoltán Major ◽  
Dóra Szarka ◽  
Tamás Boldizsár ◽  
Endre Horváth ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Phase Composition ◽  
Hydrothermal Method ◽  
Sol Gel ◽  
Tio2 Phase

A New Dielectric Material System of xLa(Mg1/2Ti1/2) O3−(1−X) CaTiO3 at Microvave Frequency

2003 ◽  
Vol 783 ◽  
Author(s):  
Yuan-Bin Chen ◽  
Cheng-Liang Huang ◽  
Che-Win Row
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Material ◽  
Material System ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Phase Effect ◽  
Temperature Coefficients ◽  
Solid State Route ◽  
Conventional Solid State Route

ABSTRACTThe dielectric properties and the microstructures of xLa(Mg1/2Ti1/2)O3−(1−x)CaTiO3 ceramics with B2O3 additions (0.25wt%) prepared with conventional solid-state route have been investigated. Doping with B2O3 (0.25wt%) can effectively promote the densification and the dielectric properties of xLa(Mg1/2Ti1/2)O3−(1−x)CaTiO3 ceramics. It is found that xLa(Mg1/2Ti1/2)O3−(1−x)CaTiO3 ceramics can be sintered at 1400°C due to the liquid phase effect of B2O3 addition observed by Scanning Electronic Microscopy. At 1425°C, 0.5La(Mg1/2Ti1/2)O3−0.5CaTiO3 ceramics with 0.25 wt% B2O3 addition possesses a dielectric constant (εr) of 43, a Q×f value of 24470 (at 8GHz) and a temperature coefficients of resonant frequency (τf) of -8.94 ppm/°C. As an increasing the content of La(Mg1/2Ti1/2)O3, the highest Q×f value of 30824(GHz) could be achieved for X=0.7.

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