Investigations of BaFe0.5Nb0.5O3 nano powders prepared by a low temperature aqueous synthesis and resulting ceramics

Köferstein, Roberto; Ebbinghaus, Stefan G.

doi:10.1016/j.jeurceramsoc.2016.12.014

Cited by 24 publications

(3 citation statements)

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“…In this work, the optical band gap is best described by an indirect allowed transition (n = 2). Thus, the optical band gap can be determined by plot (F(R)•hν) 0.5 versus hν, and extrapolating the linear regression into the hν axis [40,41]. Electrochemical impedance spectra (EIS) were performed by a Versa STAT4 potentiostat instrument (Tennessee, TN, USA).…”

Section: Photocatalyst Characterizationsmentioning

confidence: 99%

Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

2020

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TiO2-based photocatalysts synthesized by the microwave-assisted sol-gel method was tested in the photocatalytic glucose conversion. Modifications of TiO2 with type-Y zeolite (ZeY) and metals (Ag, Cu, and Ag-Cu) were developed for increasing the dispersion of TiO2 nanoparticles and increasing the photocatalytic activity. Effects of the TiO2 dosage to zeolite ratio (i.e., TiO2/ZeY of 10, 20, 40, and 50 mol %) and the silica to alumina ratio in ZeY (i.e., SiO2:Al2O3 of 10, 100, and 500) were firstly studied. It was found that the specific surface area of TiO2/ZeY was 400–590 m2g−1, which was higher than that of pristine TiO2 (34.38 m2g−1). The good properties of 20%TiO2/ZeY photocatalyst, including smaller particles (13.27 nm) and high surface area, could achieve the highest photocatalytic glucose conversion (75%). Yields of gluconic acid, arabinose, xylitol, and formic acid obtained from 20%TiO2/ZeY were 9%, 26%, 4%, and 35%, respectively. For the effect of the silica to alumina ratio, the highest glucose conversion was obtained from SiO2:Al2O3 ratio of 100. Interestingly, it was found that the SiO2:Al2O3 ratio affected the selectivity of carboxylic products (gluconic acid and formic acid). At a low ratio of silica to alumina (SiO2:Al2O3 = 10), higher selectivity of the carboxylic products (gluconic acid = 29% and formic acid = 32%) was obtained (compared with other higher ratios). TiO2/ZeY was further loaded by metals using the microwave-assisted incipient wetness impregnation technique. The highest glucose conversion of 96.9 % was obtained from 1 wt. % Ag-TiO2 (40%)/ZeY. Furthermore, the bimetallic Ag-Cu-loaded TiO2/ZeY presented the highest xylitol yield of 12.93%.

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Section: Photocatalyst Characterizationsmentioning

confidence: 99%

Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

2020

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“…We can write the following model, in which the exponent n = 2 is for DA transition, n = 2/3 for DF transition, n = 1/2 for IA transition, and n = 1/3 for IF transition (Köferstein & Ebbinghaus, 2017;Köferstein, Jäger, & Ebbinghaus, 2013).…”

Section: Optical Properties and Vb/cb Potential Positionsmentioning

confidence: 99%

Study of the mechanism pathway of sulfasalazine degradation on a novel quadripartite visible-light-driven photocatalyst

Omrani,

Nezamzadeh-Ejhieh

2024

Preprint

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A novel coupled Cu2O-CdS-BiVO4-WO3 quadripartite nanoscale catalyst was prepared and characterized by XRD, SEM-DX, x-ray mapping, and DRS techniques. Its pHpzc was also determined to be about 9. The photodegradation experiments were designed via RSM. The optimal run in the photodegradation of sulfasalazine (SSZ) included the CSSZ: 7 mg/L, pH 6.25, 30 min irradiation time, 0.45 g/L of the catalyst dose, by a catalyst with a Cu2O-CdS-BiVO4-WO3 mole ratio 3:1:1:1 under visible light illumination. The effects of the scavenging agents were also studied, and the results confirmed the critical role of superoxide in SFSZ photodegradation and the hydroxyl radicals. The photodegradation pathway obeyed the direct Z-scheme mechanism, which involved three successive binary Z-scheme components involving WO3-BiVO4, BiVO4-CdS, and CdS-Cu2O, which accumulates the photoinduced electrons in the CB-Cu2O and the holes in the VB-WO3, the more powerful reducing and oxidizing centers, respectively.

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“…These high dielectric constants are influenced by both extrinsic as well as intrinsic factors [16]. In order to improve the dielectric properties of the BFN materials, different technologies for obtaining ceramics are used [17][18][19][20][21][22][23][24][25], or modifiers are introduced into the base compound [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical Activation and Spark Plasma Sintering of the Lead-Free Ba(Fe1/2Nb1/2)O3 Ceramics

et al. 2021

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This paper investigates the impact of the technological process (Mechanochemical Activation (MA) of the powder in combination with the Spark Plasma Sintering (SPS) method) on the final properties of lead-free Ba(Fe1/2Nb1/2)O3 (BFN) ceramic materials. The BFN powders were obtained for different MA duration times (x from 10 to 100 h). The mechanically activated BFN powders were used in the technological process of the BFN ceramics by the SPS method. The measurements of the BFNxMA ceramic samples included the following analysis: Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), DC electrical conductivity, and dielectric properties. X-ray diffractions (XRD) tests showed the appearance of the perovskite phase of BFN powders after 10 h of milling time. The longer milling time (up 20 h) causes the amount of the perovskite phase to gradually increase, and the diffraction peaks are more clearly visible. Short high energy milling times favor a large heterogeneity of the grain shape and size. Increasing the MA milling time to 40 h significantly improves the microstructure of BFN ceramics sintered in the SPS technology. The microstructure becomes fine-grained with clearly visible grain boundaries and higher grain size uniformity. Temperature measurements of the BFN ceramics show a number of interesting dielectric properties, i.e., high values of electric permittivity, relaxation properties with a diffusion phase transition, as well as negative values of dielectric properties occurring at high temperatures. The high electric permittivity values predestines the BFNxMA materials for energy storage applications e.g., high energy density batteries, while the negative values of dielectric properties can be used for shield elements against the electromagnetic radiation.

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Investigations of BaFe0.5Nb0.5O3 nano powders prepared by a low temperature aqueous synthesis and resulting ceramics

Cited by 24 publications

References 65 publications

Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

Study of the mechanism pathway of sulfasalazine degradation on a novel quadripartite visible-light-driven photocatalyst

Mechanochemical Activation and Spark Plasma Sintering of the Lead-Free Ba(Fe1/2Nb1/2)O3 Ceramics

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