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1.
Nanostructured CeO2/CuO composites are synthesized using a facile hydrothermal reaction. Results signify that Cu ions prefer to enter into CeO2 lattice forming solid solution at low concentration, and would be transformed into CuO phase at moderate concentration. Moreover, the addition of CuO species into CeO2 promotes the reduction of Ce4+ and the creation of oxygen vacancy (VO) defects. Raman analyses confirm VO concentration initially increases and then decreases with the increasing CuO phase and the sample Ce1Cu2 exhibits the highest defect concentration. The room temperature ferromagnetic behavior is observed firstly in CeO2/CuO nonmagnetic system and the maximal saturation magnetization appears in Ce1Cu2. The emergent ferromagnetism appears to be relevant to the extensive VO defects, which can be interpreted by the indirect double-exchange model. The synthetic interaction between CeO2 and CuO results in the redshift of the bandgap in prepared CeO2/CuO nanocomposites. 相似文献
2.
A sol–gel chemical route was adopted to prepare the zinc oxide (ZnO) nanoparticles as small as 4 nm. UV-curable ZnO-acrylic nanocomposites were then prepared by employing 3-(trimethoxysilyl)propyl methacrylate (TPMA) as the surface modification agent of ZnO particles. UV–vis analysis revealed a high optical transparency (>95%) in visible light region for nanocomposite thin films with ZnO contents up to 20 wt.%. The addition of ZnO nanoparticles also enhanced the dielectric constants of nanocomposites and the dielectric constants greater than 4 in frequencies ranging from 1 to 600 MHz was obtained in the samples containing 10 wt.% of ZnO nanoparticles. A comparison of experimental results and theoretical calculation indicated that the interfacial polarizations in between ZnO nanoparticles and polymer matrix may play an important role in the enhancement of dielectric properties of nanocomposites. 相似文献
3.
The x(CuO)/(1−x)Ni(OH)2 [x=0, 0.1 and 0.3] nanocomposites were prepared by the hydrothermal method in the presence of the surfactant polyethylenglycol-10000 (PEG-10000). X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the as-prepared samples. The increase of the CuO content led to the increase of the crystallite size of both, the β-Ni(OH)2 and the CuO. The increase in the crystallite size greatly affects the band gap energy of the as-prepared nanocomposites. The band gap energies of the x(CuO)/(1−x)Ni(OH)2 nanocomposites were estimated by UV–vis spectroscopic method. UV–vis spectroscopic results showed an apparent decrease in the direct band gap energies. The x(CuO)/(1−x)Ni(OH)2 [x=0, 0.1 and 0.3] nanocomposites show low band gap energies compared to the Ni(OH)2 bulk materials. The enhanced optical properties lead to their possible use in photocatalytic and photovoltaic applications. 相似文献
4.
Satheesh Kaveri Lavanya Thirugnanam Mrinal Dutta Jayavel Ramasamy Naoki Fukata 《Ceramics International》2013,39(8):9207-9214
We report on the synthesis of CdS/reduced graphene oxide (rGO) composite by a wet chemical method. Thiourea was used both as a sulfur source and as a reducing agent to convert graphene oxide to rGO. The structural and morphological confirmation for the reduction of graphene oxide and the formation of the CdS/rGO composite was demonstrated by X-ray diffractometry, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. Photoluminescence spectra of the composite exhibited a more efficient luminescence quenching in comparison with pure CdS nanoparticles. The composite demonstrated 99% photodegradation of methyl orange under UV irradiation, which is much superior than the photodegradation of methyl orange under similar conditions exhibited by CdS nanoparticles (72%). 相似文献
5.
《Ceramics International》2016,42(12):14094-14099
The effect of graphene concentration on the photovoltaic and UV detector applications of ZnS/graphene nanocomposites was investigated. The nanocomposites were synthesized by a green, cost-effective, and simple co-precipitation method with different graphene concentrations (5, 10, and 15 wt%) using L-cysteine amino acid as a surfactant and graphene oxide (GO) powder as a graphene source. Transmission electron microscopy (TEM) images showed that the ZnS NPs were decorated on GO sheets and the GO caused a significant decrease in ZnS diameter size. The results of X-ray diffraction (XRD) patterns, Raman, and Fourier transform infrared (FTIR) spectroscopy indicated that the GO sheets were changed into reduced graphene oxide (rGO) during synthesis process. Therefore, L-cysteine amino acid played its role as a reducing agent to reduce the GO. Photovoltaic measurements showed that the graphene caused to increase the efficiency of solar-cell application of ZnS/rGO nanocomposites. In addition, our observation showed that the nanocomposites were suitable as ultraviolet (UV) detectors and graphene concentration increased the responsibility of the detectors. 相似文献
6.
Kansong Chen Rui Hu Xinran Feng Kun Xie Yang Li Haoshuang Gu 《Ceramics International》2013,39(8):9109-9114
A multicomponent oxide, Bi4Ti3O12/TiO2 heterostructure was successfully synthesized via a two-step synthesis route based on an anodic oxidation procedure and a subsequent hydrothermal technique. X-ray diffraction confirmed that the composition of the as-fabricated sample was a Bi4Ti3O12/TiO2 composite. Scanning and transmission electron microscopy observation reveals that the as-synthesized sample consisted of TiO2 nanotubes decorated with Bi4Ti3O12 nanocubes. The photocatalytic property of Bi4Ti3O12/TiO2 heterostructure was evaluated by decomposing methyl orange as a model organic compound. Compared with the unmodified TiO2 nanotube arrays, Bi4Ti3O12/TiO2 heterostructure exhibits a higher photocatalytic activity in the decomposition of methyl orange under UV light. The prominent photocatalytic activity could be ascribed to the formation of the heterostructure between Bi4Ti3O12 and TiO2 as well as a good dispersity of Bi4Ti3O12 nanocubes, which could effectively separate the photogenerated carriers and reduce the electron–hole recombination. 相似文献
7.
《Ceramics International》2020,46(3):3345-3352
The luminescent characteristics of spherical titanium dioxide (TiO2) nanoparticles (NP's) doped with Sm3+/Yb3+ and Tm3+/Yb3+ with and without a silica coating were analyzed. These nanoparticles were synthesized using the spray pyrolysis technique and coated with silica through a wet chemical process. The Sm3+/Tm3+ and Yb3+ doping induces a triphasic poly-crystalline structure of rutile and anatase TiO2 and a Sm2Ti2O7/Tm2Ti2O7 cubic phase. A Williamson-Hall analysis was used to monitor the tensions of the NP's crystallites at the various doping concentrations and with addition of the silica shell. The luminescent spectra presented the characteristic emission peaks for the electronic energy levels transitions of the Sm3+/Tm3+ and Yb3+ ions. The Sm3+/Yb3+ co-doped NP's showed a maximum emission peak in the visible region at 612 nm, associated with 4G5/2 → 6H7/2 transitions of the Sm3+ ions. The IR emission peak at 973 nm (2F5/2 → 2F7/2) pertaining to Yb3+. For the combination of Tm3+/Yb3+, two emissions associated with Tm3+ ions were observed at 440 nm (1D2 → 3F4) and 806 nm (3H4 → 3H6). The emission at 973 nm (2F5/2 → 2F7/2) is correlated to the Yb3+ ions. Silica coating of the NP's resulted in luminescence emission intensity increase of about 4 times. 相似文献
8.
Soumya SarkarProbal Kr. Das 《Ceramics International》2012,38(1):423-432
Multiwalled carbon nanotube (MWCNT)/alumina (Al2O3) nanocomposites containing CNT from 0.15 vol.% to 2.4 vol.% have been successfully fabricated by simple wet mixing of as-received commercial precursors followed by pressureless sintering. Extent of densification of nanocomposites sintered at low temperature (e.g. 1500 °C) was <90%, but increased up to ∼99% when sintered at 1700 °C and offered superior performance compared to pure Al2O3. Nanocomposites containing 0.3 vol.% MWCNT and sintered at 1700 °C for 2 h in Argon led to ∼23% and ∼34% improvement in hardness and fracture toughness, respectively, than monolithic Al2O3. In addition, the highest improvement (∼20%) in bending strength was obtained for 0.15 vol.% MWCNT/Al2O3 nanocomposite compared to pure Al2O3. Weibull analysis indicated reliability of nanocomposites increased up to 0.3 vol.% MWCNT, whereas, beyond that loading consistency was the same as obtained for pure Al2O3. Detailed microstructure and fractographic analysis were performed to assess structure-property relationship of present nanocomposites. 相似文献
9.
《Ceramics International》2015,41(4):5656-5662
A new route for the synthesis of aminophenol grafted and Ag NPs decorated reduced graphene sheet (Ag-RGS) was developed as an effective antibacterial nanostructure. The nucleophilic substitution reaction of amine group of aminophenol with epoxy group of GO in the presence of silver nitrate and subsequent reduction with hydrazine generated Ag-RGS nanocomposite. The morphology and structure of the as-synthesized nanocomposite was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. TEM images of Ag-RGS revealed that the silver nanoparticles were decorated on the surface of the graphene sheet. The presence of phenolic groups and silver nanoparticles on the surface of Ag-RGS showed synergistic effect on antibacterial activity against Escherichia coli and Staphylococcus aureus. This feature of the Ag-RGS nanocomposite showed that it can be a promising candidate in broad range of antibiotics. 相似文献
10.
《Ceramics International》2016,42(13):14452-14455
The effect of the thermal annealing temperature was investigated on ZnO tetrapods grown by a thermal evaporation method. The ZnO tetrapods were synthesized by thermal evaporation of Zn powder in air. The annealing was done in an oxygen gas environment at temperatures ranging from 400 to 1000 °C for 1 h. As the annealing temperature increased from 400 °C to 800 °C, the morphology of the tetrapod remained unchanged; however, the size of the tetrapods increased. With a further increase in the annealing temperature from 800 °C to 1000 °C, the ZnO tetrapod changed drastically to nanoneedles. As-grown and annealed samples had an identical crystal structure, which was a wurtzite structure. A strong and sharp ultraviolet emission at 380 nm was observed for the 600 °C –annealed sample indicating the high crystalline quality. The ultraviolet emission intensity decreased abruptly for the samples annealed at 800 °C and 1000 °C, which exhibits the degradation in crystallinity. 相似文献
11.
Mg-doped ZnO/reduced graphene oxide (rGO) nanocomposites were synthesized using a facile and cost-effective sol-gel procedure to detect acetic acid vapor. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy, and photoluminescence (PL) analysis were utilized to characterize morphologies, compositions of the nanocomposites, and optical properties of the synthesized nanostructures. The gas sensing measurements of spin-coated Mg-doped ZnO/rGO thin films were carried out for a temperature range of 150–350?°C at various acetic acid vapor concentrations. It was found that the Mg-doped sample with 20?wt%/v of GO solution concentration exhibited the response/recovery time of 60?s/35?s with the best response of ~?200% for 100?ppm of acetic acid at 250?°C. 相似文献
12.
A facile solvent-based synthesis route based on the oxidation–reduction reaction between graphene oxide (GO) and SnCl2·2H2O has been developed to synthesize SnO2/graphene (SnO2/G) nanocomposites. The reduction of GO and the in situ formation of SnO2 nanoparticles were achieved in one step. Characterization by X-ray diffraction (XRD), ultraviolet-visible (UV–vis) absorption spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FESEM) confirmed the feasibility of using the solvothermally treated reaction system to simultaneously reduce GO and form SnO2 nanoparticles with an average particle size of 10 nm. The electrochemical performance of SnO2/graphene showed an excellent specific capacitance of 363.3 F/g, which was five-fold higher than that of the as-synthesized graphene (68.4 F/g). The contributing factors were the synergistic effects of the excellent conductivity of graphene and the nanosized SnO2 particles. 相似文献
13.
Fangyi Weng Daqin Chen Yuansheng Wang Yulong Yu Ping Huang Hang Lin 《Ceramics International》2009,35(7):2619-2623
Transparent glass ceramics containing YF3 nano-crystals were fabricated by heat treatment of the SiO2–Al2O3–NaF–YF3–LnF3 (Ln = Er, Yb) glasses. X-ray diffraction and transmission electron microscopy analyses evidenced the homogeneous distribution of spherical YF3 nano-crystals sized 25–30 nm among the glassy matrix. Energy dispersive X-ray spectroscopy measurement, combined with the Stark splitting of the absorption and emission bands, verified the incorporation of Er3+ and Yb3+ ions into YF3 nano-crystals. The infrared to visible up-conversion emission of Er3+ intensified with the increasing of Yb3+ concentration, ascribing to the increase of the efficiency of non-radiative energy transfer from Yb3+ to Er3+ which exceeded 45% for the 0.5Er3+/1.0Yb3+ co-doped sample. The up-conversion luminescence at 545 and 660 nm were affirmed coming from two-photon excitation process. 相似文献
14.
《Ceramics International》2017,43(8):6192-6200
Ni1−xZnxFe2O4 (0≤x≤1) nanocrystals were prepared by a soft mechanochemical approach. The structure and morphology were assessed via X-ray powder diffractometery (XRD), infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM) and Energy dispersive spectroscopy (EDS). The magnetic characteristics have been evaluated using vibrating sample magnetometer (VSM). The optical properties were explored by diffuse reflectance UV–visible spectrophotometry (DRS). The substitution of Zn into the Ni1−xZnxFe2O4 nanocrystals increased the mean nanocrystal size from 4 to 19 nm. The FTIR and Raman spectroscopies showed that the substitution with Zn up to x=0.5 in Ni1−xZnxFe2O4 nanocrystals results in a migration of Fe ions from tetrahedral to octahedral sites, leading to an improvement of the saturation magnetization value to 33.8 emu/g. At the same time, the optical band gap decreased from 2.6 to 1.93 eV due to the increase of the Zn content from x=0 to x=1. These promising characteristics of Ni1−xZnxFe2O4 nanocrystals make them suitable for the use in the field of magnetically recoverable catalysts including those for energy applications. 相似文献
15.
《Ceramics International》2017,43(6):5292-5301
The development of heterostructured semiconductor photocatalysts makes a noteworthy advancement in environmental purification technology. In this work, a novel heterostructured Bi2O3−CeO2−ZnO, fabricated by a combination of microwave-assisted hydrothermal and thermal decomposition methods, showed an enhanced photocatalytic activity for Rhodamine B (RhB) degradation under sunlight, as compared to pristine ZnO, Bi2O3, CeO2, and commercial Degussa TiO2-P25. The obtained products were thoroughly characterized by various techniques including X- ray powder diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), elemental color mapping, energy-dispersive X-ray spectroscopy (EDAX), Raman spectrometry, Fourier transform infrared (FT-IR) spectroscopy, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL) spectroscopy. PXRD analysis reveals that the heterostructure has the monoclinic lattice phase of α-Bi2O3, the cubic phase of CeO2 and the hexagonal wurtzite phase of ZnO. FE-SEM images show that Bi2O3−CeO2−ZnO has an ordered mixture of nanorod and nanochain structures. EDAX, elemental color mapping, Raman and FT-IR analyses confirm the successful formation of the heterostructured Bi2O3−CeO2−ZnO. The UV–Vis DRS results demonstrate that Bi2O3−CeO2−ZnO exhibits wide visible-light photoabsorption in 400–780 nm range. Moreover, the reduction in PL intensity of the heterostructured Bi2O3−CeO2−ZnO, when compared to the pristine Bi2O3, CeO2, and ZnO, indicates enhanced charge separation. The study on the mechanism displayed that the improved photocatalytic activity of Bi2O3−CeO2−ZnO could be attributed to (1) the efficient separation of photoinduced electrons and holes of the photocatalysts, caused by the vectorial transfer of electrons and holes among ZnO, CeO2 and Bi2O3, and (2) the wide visible-light photoabsorption range. This study introduces a new class of promising sunlight-driven photocatalysts. 相似文献
16.
T. Rodriguez-Suarez J.F. BartoloméA. Smirnov S. Lopez-EstebanL.A. Díaz R. TorrecillasJ.S. Moya 《Ceramics International》2011,37(5):1631-1636
In the present work, the processing and characterization of electroconductive Alumina-TiC-Ni nanocomposites obtained by Spark Plasma Sintering (SPS) are described. These nanocomposites are singular due to the excellent mechanical properties they present (particular regarding Vickers hardness, 25.6 ± 0.7 GPa), as well as their extremely good wear behaviour, studied under “ball-on-disk” dry sliding conditions. The wear rate obtained was 25 times (almost 1.5 orders of magnitude) smaller than the value obtained for a monolithic alumina sintered under the same conditions. Flexural strength had been improved up to 75% with respect to the monolithic alumina processed under the same conditions. As these nanocomposites can be machined by electroerosion (EDM), they can adopt any shape for devices requiring a good mechanical performance and low wear rates. 相似文献
17.
《Ceramics International》2016,42(12):13359-13367
We report the synthesis of flexible ceramic composites with a high tensile strength (536.33±7.23 MPa) using carbon nanotube sheet aligned by mechanically stretching process. The process is based on the infiltration and pyrolysis of liquid ceramic precursor into aligned carbon nanotube sheet. Mechanical properties and microstructure of the resultant composites are investigated. The resultant nanocomposites maintain well-aligned carbon nanotube morphology with high volume fraction (60%) and long pullout (15 µm), contributing to a high degree of load-transfer efficiency and toughening. Flexibility test reveals that such ceramic nanocomposites retain the original mechanical properties and microstructures after one thousand repetitions of 75% bending deformation, showing excellent compliance and durability. Applications requiring materials with high flexibility and mechanical properties can benefit from this research. 相似文献
18.
M. Aminzare A. Eskandari M.H. Baroonian A. Berenov Z. Razavi Hesabi M. Taheri S.K. Sadrnezhaad 《Ceramics International》2013
Two different hydroxyapatite based composites reinforced by oxide ceramic (20 wt%) nano crystals were synthesized by high-energy ball milling and sintered by pressure less technique. Alumina and titania nanoparticles as secondary phases improved densification and mechanical behavior of apatite and postponed its decomposition to the tricalcium phosphate (TCP) phases at elevated temperatures. Increasing the relative density of apatite using nano reinforcements leads to enhance the bending strength by more than 40% and 27% (as compared to the pure HA) and increase the hardness from 2.52 to 5.12 (Al2O3 composite) and 4.21 (TiO2 addition) GPa, respectively. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction spectroscopy were employed to study morphologies, fracture surfaces and phase compositions, respectively. The morphological study and micro structural analysis confirm the X-ray diffraction and relative density diagrams. 相似文献
19.
《Ceramics International》2017,43(17):15040-15046
A process of obtaining N-doped TiO2 nanotubes sensitized by CdS nanoparticles is presented, including detailed characterizations performed along the synthesis. Transparent TiO2 films consisting of nanotubes, 2.5 µm long and of ~60 nm inner diameter, were obtained after anodization of a titanium film deposited onto FTO glass substrate. N-doping was achieved by annealing of TiO2 film in ammonia. X-ray Photoelectron Spectroscopy measurements showed that nitrogen was substitutionally incorporated in the TiO2 matrix, with the N:Ti concentration ratio of 1:100. The doping changed the optical properties of the material in such a way that the absorption edge was shifted from 380 nm to 507 nm, as observed from diffuse reflectance spectra. The influence of the microwave (MW) irradiation on the synthesized CdS quantum dots and their optical properties was investigated. It was shown that the diameter of CdS nanoparticles was increased due to releasing of S2- ions from dimethyl sulfoxide (DMSO) as a consequence of the MW treatment. The (N)TiO2 films were then used as substrates for matrix assisted pulsed laser deposition of the CdS quantum dots with DMSO as a matrix. The laser parameters for the deposition were optimized in order to preserve the nanotubular structure open, the latter being an important feature of this type of photoanode. The structure obtained under optimized conditions has an additional absorption edge shift, reaching 603 nm. 相似文献
20.
Nanocomposites of the (1 − x)PZT-xBT system were fabricated by the bimodal particle concept. The effect of fabricating conditions on structural characteristics and dielectric properties of the ceramics was investigated using XRD, SEM, and a standard dielectric measurement. The ceramic–solid solutions and -nanocomposites in the PZT–BT system were comparatively explored. It was clearly seen that the microstructures and the dielectric properties of PZT–BT ceramic-nanocomposites are totally different from those of ceramic–solid solutions. The dielectric behavior of ceramic-nanocomposites displayed superimposition of two phase transitions with a lower maximum value of the dielectric constant than that of the solid solutions. 相似文献