Synthesis of inside-out core–shell perovskite-type oxide nanopowder

Mazar, Omri; Schroeder, Michael A.; Tsur, Yoed

doi:10.1016/j.cej.2010.11.084

Cited by 6 publications

(3 citation statements)

References 36 publications

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“…However, the difference between the O 2 /O 2 •-couple and WS 2 -CB is large for a direct electron exchange and a low activity is expected since the electron transfer should occur iso-energetically. Some strategies have been attempted to overcome such drawback and a growing interest has been paid to hetero-systems [22,23]. As mentioned above, coupled SCs enhance the photocatalytic efficiency by extending the spectral photoresponse toward longer wavelengths and hinder the loss of (e -/h ? )…”

Section: Photocatalysismentioning

confidence: 99%

Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Bassaid

Bellal

Trari

2015

Reac Kinet Mech Cat

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The photodegradation of orange II (OII) is successfully achieved on the new hetero-system WS 2 /TiO 2 under UV illumination. The nano sized bi-functional catalyst is prepared by sol gel and calcined at *450°C. The X-ray diffraction shows noticeably broad peaks and TiO 2 is therefore less crystallized with the anatase phase. The sensitizer WS 2 presents a direct optical transition at 1.72 eV. The Mott-Schottky plot (C -2 -V) is characteristic of n type conduction from which a flat band potential of 0.17 V SCE and a donor density of 5.30 9 10 17 cm -3 are determined. An energy band diagram is established, predicting an electron transfer from WS 2 to TiO 2 ; the injection process is confirmed by the photocurrent measurements at different concentrations. Upon increasing the mass of WS 2 , the activity increases and the best performance occurs on 30 % WS 2 /TiO 2 . A conversion of 98 % is reported in aerated solution for OII concentration of 10 ppm in less than 90 min. The oxidation follows a first order kinetic with a rate constant of 4.8 9 10 -2 min -1 .

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Section: Photocatalysismentioning

confidence: 99%

Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Bassaid

Bellal

Trari

2015

Reac Kinet Mech Cat

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“…Core-shell bulk materials are formed due to excess of dopants above the solubility limit, 68,113 improper homogenization of raw materials due to suppressed diffusion, 76,91,114 formation of a liquid phase that precipitates due to limited solute solubility 67,80,85,94,115 (i.e., Ostwald ripening process), 116 controlled diffusion due to strain gradients, 117 and alignment of nanoparticles into ordered superstructures in the mesoscale. 92 Exceeding the solubility limit leads to a thermodynamically stable core-shell material, whereas the other mechanisms result in a kinetically stable core-shell microstructure.…”

Section: Core-shell Approachmentioning

confidence: 99%

Core–Shell Lead–Free Piezoelectric Ceramics: Current Status and Advanced Characterization of the Bi_1/2Na_1/2TiO₃–SrTiO₃ System

et al. 2015

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The design of core-shell materials affords additional degrees of freedom to tailor functional properties as compared to solid solution counterparts. Although to date most of the work in core-shell materials has focused on dielectrics, piezoelectric coreshell ceramics may gain similar interest. Generalities of core-shell functional ceramics features are addressed in this work. A model system, Bi 1/2 Na 1/2 TiO 3 -SrTiO 3 , is introduced to discuss structure-property relationships. We demonstrate that this system features a core-shell microstructure for the composition corresponding to 25 at.% Sr. The material is studied by means of macroscopic functional properties and in situ structural characterization techniques at different length scales, such as X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The evolution of the core-shell with field and temperature determines its functional properties. The high strain of the system, 0.3% at 4 kV/mm, is due to an electric-field-induced phase transition of the core and shell. Upon field removal the core remains in a poled state, whereas the shell is characterized by a reversible transformation. The reversibility of the phase transition of shells and associated switching are key features in the observed giant strain. Dielectric anomalies are found to be related to changes in oxygen octahedral tilting angles within the core and shell.

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“…Nb 2 O 5 ‐modified Ba 0.991 Bi 0.006 TiO 3 ceramics prepared using precipitation coating method was found to satisfy X8R specification in our previous study, and the dielectric properties needs to be further improved . However, many investigations have been carried out to gain understanding of the formation mechanism of the core/shell structure in both academic and industrial circles . Therefore, in this paper, we studied the sintering characteristics of Ba 0.991 Bi 0.006 TiO 3 @Nb 2 O 5 –Co 3 O 4 is essential to elucidate the formation mechanisms of the core–shell microstructure.…”

Section: Introductionmentioning

confidence: 92%

Core–Shell Structure and Dielectric Properties of Ba_0.991Bi_0.006TiO₃@Nb₂O₅–Co₃O₄ Ceramics

et al. 2016

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To meet the needs of future multilayer ceramic capacitors (MLCCs), thinner dielectric layers are necessary. To achieve this goal, the grain size and uniformity of the particles must be effectively controlled. In this study, we confirmed a core-shell particle structure by means of X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The dielectric properties of the ceramics were measured using an LCR meter. We found Ba 0.991 Bi 0.006 TiO 3 particles form a core that was coated with a homogeneous Nb 2 O 5 -Co 3 O 4 layer (~9 nm). The relationship between core-shell structure and e r -T curves of the Ba 0.991 Bi 0.006 TiO 3 @Nb 2 O 5 -Co 3 O 4 ceramics by different sintering temperature has been investigated. Dense, fine-grained Ba 0.991 Bi 0.006 TiO@Nb 2 O 5 -Co 3 O 4 ceramics were obtained by sintering at 1160°C. The ceramics met the X8R requirements, with a maximum dielectric constant of 2795, and a low dielectric loss at room temperature of 0.89%.

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Synthesis of inside-out core–shell perovskite-type oxide nanopowder

Cited by 6 publications

References 36 publications

Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Core–Shell Lead–Free Piezoelectric Ceramics: Current Status and Advanced Characterization of the Bi_1/2Na_1/2TiO₃–SrTiO₃ System

Core–Shell Structure and Dielectric Properties of Ba_0.991Bi_0.006TiO₃@Nb₂O₅–Co₃O₄ Ceramics

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Synthesis of inside-out core–shell perovskite-type oxide nanopowder

Cited by 6 publications

References 36 publications

Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Core–Shell Lead–Free Piezoelectric Ceramics: Current Status and Advanced Characterization of the Bi1/2Na1/2TiO3–SrTiO3 System

Core–Shell Structure and Dielectric Properties of Ba0.991Bi0.006TiO3@Nb2O5–Co3O4 Ceramics

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Product

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Core–Shell Lead–Free Piezoelectric Ceramics: Current Status and Advanced Characterization of the Bi_1/2Na_1/2TiO₃–SrTiO₃ System

Core–Shell Structure and Dielectric Properties of Ba_0.991Bi_0.006TiO₃@Nb₂O₅–Co₃O₄ Ceramics