Preparation and Optical Property of ZnS:Mn/XO2 (X=Ti, Si) Nanoparticles with Core/Shell Structure

2015 ◽  
Vol 814 ◽  
pp. 376-383
Author(s):  
Yu Long Wang ◽  
Wen Tao Zhang ◽  
Jian Ping Long ◽  
Pei Cong Zhang
Keyword(s):  
Optical Property ◽  
Luminescence Intensity ◽  
Shell Structure ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Tetrabutyl Titanate ◽  
Core Shell ◽  
Si Nanoparticles ◽  
Core Shell Structure ◽  
Co Precipitation

In this paper, Mn2+ doped ZnS (ZnS:Mn) nanoparticles were prepared by co-precipitation method. And then different thickness of TiO2 and SiO2 inorganic shell were coated on prepared ZnS:Mn through the hydrolysis reaction of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS). ZnS:Mn crystal and core/shell structure were described by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical property of all ZnS:Mn/XO2 (X=Ti, Si) nanoparticles were investigated by photoluminescence (PL) spectrometer. The effect of Mn2+ concentration and XO2 (X=Ti, Si) shell thickness on luminescence intensity of ZnS:Mn/XO2 was studied. The results showed that with TiO2 and SiO2 shell thickening, Mn2+ emission of ZnS:Mn/XO2 samples increased first and then decreased. When the thickness of inorganic shell (molar ratio of shell and core amount) reached to 0.5 (TiO2) and 1.0 (SiO2), the optimal luminescence intensity was obtained. The emission of ZnS:Mn/TiO2 and ZnS:Mn/SiO2 was 2.0 and 1.5 times more in intensity than that of uncoated ZnS: Mn, respectively.

scholarly journals Core-Shell Structure and Dielectric Properties of Ba0.6Sr0.4TiO3@ Fe2O3 Ceramics Prepared by Co-Precipitation Method

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 623
Author(s):  
Zhuo Li ◽  
Chenbo Wang ◽  
Zixuan Wang ◽  
Dandan Zhang ◽  
Yangxiao Qin ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Shell Structure ◽  
Ceramic Materials ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
Reaction Conditions ◽  
Core Shell Structure ◽  
Co Precipitation ◽  
Different Content

Ba0.6Sr0.4TiO3 (BST) ceramic materials have been widely used in the field of multilayer ceramic capacitors. Surface modification through the surface coating to form a heterogeneous layer could effectively improve the dielectric properties. In this work, BST powders were prepared by a co-precipitation method. The effects of reaction conditions on the microstructure of the BST powder were investigated. The reaction temperatures significantly affected the morphology of BST powder, and the rhombic-type particles were obtained with the reaction temperature around 80 °C. Meanwhile, the BST@Fe2O3 was prepared by the chemical precipitation method using BST powders with rhombic-type microstructure as “core”, and the so-called “core-shell” microstructure was confirmed in the BST@Fe2O3 powder. Then, BST@x wt%Fe2O3 (x = 2.5, 5, 7.5, and 10, denoting the different content of Fe2O3) ceramics were further prepared, and the influence of “core-shell” structure on the phase structure, microstructure, and dielectric properties was investigated. With the increasing of Fe2O3 content, the ferroelectric–paraelectric phase transition temperature shifts toward lower temperatures, and dielectric peaks gradually become broad and frequency-dependent, which may be due to inconsistent chemical composition from core to shell.

Preparation of Amorphous Calcium Phosphate/Triclcium Silicate Composite Powders

2009 ◽  
Vol 79-82 ◽  
pp. 1643-1646 ◽  
Author(s):  
Qing Lin ◽  
Yan Bao Li ◽  
Xiang Hui Lan ◽  
Chun Hua Lu ◽  
Zhong Zi Xu
Keyword(s):  
Calcium Phosphate ◽  
Shell Structure ◽  
Amorphous Calcium Phosphate ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
X Ray ◽  
Core Shell Structure

The amorphous calcium phosphate (ACP)/tricalcium silicate (Ca3SiO5, C3S) composite powders were synthesized in this paper. The exothermal behavior of C3S determined by isothermal conduction calorimetry indicated that the ACP could be synthesis by chemical precipitation method during the induction period (stage II) of C3S. The composite powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results indicated that nanosized ACP particles deposited on the surface of C3S particles to form core-shell structure at pH=10.5, and the nCa/nP of ACP could be controlled between 1.0 and 1.5. The core-shell structure is stable after sintered at 500 oC for 3 h to remove the β-cyclodextrin (β-CD). As compared with the irregular C3S particles (1~5 μm), the composite powders particles are spherical with a diameter of 40~150 μm. Therefore, to obtain the smaller size of composite powders, it is expected to avoid the aggregate of C3S particles in the aqueous solution by addition of dispersant. As compared with C3S, the composite powders may contribute better injectability, strength and biocompatibility.

scholarly journals Design of Scorodite@Fe3O4 Core–Shell Materials and the Fe3O4 Shell Prevents Leaching of Arsenic from Scorodite in Neutral and Alkaline Environments

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 523
Author(s):  
Yang Wang ◽  
Zhihao Rong ◽  
Xincun Tang ◽  
Shan Cao
Keyword(s):  
Photoelectron Spectroscopy ◽  
Shell Structure ◽  
Molar Ratio ◽  
Alkaline Solutions ◽  
Arsenic Content ◽  
Core Shell ◽  
X Ray ◽  
Core Shell Structure ◽  
The Stability ◽  
Fe3o4 Core

In recent years, arsenic pollution has seriously harmed human health. Arsenic-containing waste should be treated to render it harmless and immobilized to form a stable, solid material. Scorodite (iron arsenate) is recognized as the best solid arsenic material in the world. It has the advantages of high arsenic content, good stability, and a low iron/arsenic molar ratio. However, scorodite can decompose and release arsenic in a neutral and alkaline environment. Ferroferric oxide (Fe3O4) is a common iron oxide that is insoluble in acid and alkali solutions. Coating a Fe3O4 shell that is acid- and alkali-resistant on the surface of scorodite crystals will improve the stability of the material. In this study, a scorodite@Fe3O4 core–shell structure material was synthesized. The synthesized core–shell material was detected by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman, and energy-dispersive X-ray spectroscopy (EDS) techniques, and the composition and structure were confirmed. The synthesis condition and forming process were analyzed. Long-term leaching tests were conducted to evaluate the stability of the synthesized scorodite@Fe3O4. The results indicate that the scorodite@Fe3O4 had excellent stability after 20 days of exposure to neutral and weakly alkaline solutions. The inert Fe3O4 shell could prevent the scorodite core from corrosion by the external solution. The scorodite@Fe3O4 core–shell structure material was suitable for the immobilization of arsenic and has potential application prospects for the treatment of arsenic-containing waste.

scholarly journals Synthesis and Surface Properties of Silica Spheres with Core Shell Structure by One Convenient Method

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
D. P. Das ◽  
K. M. Parida ◽  
B. K. Mishra
Keyword(s):  
Mesoporous Silica ◽  
Shell Structure ◽  
Cost Effective ◽  
Molar Ratio ◽  
Ammonium Bromide ◽  
Core Shell ◽  
Silica Spheres ◽  
Core Shell Structure ◽  
Cetyltrimethyl Ammonium ◽  
Mesoporous Silica Spheres

Earlier, we have published a paper on the preparation of silica sphere using propanol as cosurfactant. We report here a highly cost-effective method of preparation of mesoporous silica spheres with core shell structure using sodium silicate as silica precursor, cetyltrimethyl ammonium bromide (CTAB) as surfactant, and methanol as cosurfactant. Thus after removal of the template by dissolutions or/and activation at higher temperature, mesoporous silica spheres with core shell structure were obtained. The products prepared with methanol to CTAB molar ratio 8.5 : 1 were confirmed to give best results. All the spherical products have very large surface area (∼589–1044 m2/g), pore volume (∼0.98–1.41 cm3/g), and ordered pore structure.

scholarly journals Preparation of Ceria-Coated Silica Nanoparticles and Their Chemical Mechanical Planarization Performance on Si-Face 6H-SiC Substrates

2021 ◽  
Author(s):  
Zifeng Ni ◽  
Guomei Chen ◽  
Laijun Xu ◽  
Ping Zhang ◽  
Mengjiao Dai ◽  
...  
Keyword(s):  
Shell Structure ◽  
Chemical Mechanical Planarization ◽  
Precipitation Method ◽  
Core Shell ◽  
Aqueous Mixtures ◽  
Amorphous Sio2 ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Core Shell Structure

Abstract Ceria-coated silica (SiO2/CeO2) composite abrasives were prepared through a novel homogeneous precipitation method using commercial silica (SiO2) sol as the silicon resource and cerium nitrate (Ce(NO3)3) and hexamethylenetetramine (HMT) aqueous mixtures as coating precursors. The phase composition, nano-topography, size distribution, and chemical structure of as-prepared particles were characterized by X-ray diffraction, transmission electron microscopy, Zetasizer Nano ZS90 and Fourier infrared spectra. In addition, the possible coating mechanism was discussed. Then, chemical mechanical planarization behaviors of SiO2 sol, ceria (CeO2) sol, and the novel abrasives and on Si-face (0001) 6H-SiC were investigated by atomic force microscopy. The results indicated that the composite particles were mono-dispersed nano-spheres composed of amorphous SiO2 core and cubic fluorite CeO2 shell, possessing complete core-shell structure and particle size of about 110 nm. CeO2 shell (10 nm) grew on the surface of SiO2 core by formation of Ce-O-Si chemical bonds, forming stable core-shell structure. SiO2/CeO2 composite abrasives provided an exponentially high material remove rate (MRR) of 1207 nm/h and an impressive surface finish with roughness average (Ra) 0.216 nm due to its active chemical property and unique structure.

scholarly journals Highly efficient reduction of 4-nitrophenolate to 4-aminophenolate by Au/γ-Fe2O3@HAP magnetic composites

RSC Advances ◽  
2019 ◽  
Vol 9 (18) ◽  
pp. 10272-10281 ◽  
Author(s):  
Yide Xia ◽  
Ying Liu ◽  
Nannan Shi ◽  
Xungao Zhang
Keyword(s):  
Shell Structure ◽  
Au Nanoparticles ◽  
Precipitation Method ◽  
Core Shell ◽  
Magnetic Composites ◽  
The Core ◽  
Highly Efficient ◽  
Efficient Reduction ◽  
Core Shell Structure

In this article, the catalyst Au/γ-Fe2O3@hydroxyapatite (Au/γ-Fe2O3@HAP) consisting of Au nanoparticles supported on the core–shell structure γ-Fe2O3@HAP was prepared through a deposition–precipitation method.

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