共查询到20条相似文献,搜索用时 15 毫秒
1.
《Ceramics International》2021,47(24):34189-34198
Introduction of artificial pinning centres in different morphology is a beneficial way to improve the flux pinning properties of a YBCO compound. In the present study, we report the effect of addition of sodium niobate (NaNbO3) nanostructures in two different form i.e. nanorods (NRs) and nanoparticles (NPs) with a varied wt% (0, 0.5, and 1 wt%) on the pinning capabilities of bulk YBCO polycrystalline samples. The orthorhombic crystal structure of YBCO was confirmed by the XRD spectra even in the nanocomposite samples. The existence of NPs or NRs on the surface and between the superconducting grains of YBCO was confirmed by morphological analysis. The critical temperature (Tc) remains almost unchanged as compared to pure YBCO on addition of NaNbO3 nanostructure in YBCO compound upto 1 wt% concentration. Even at higher fields (upto 6 T) and higher temperatures (upto 75 K), the addition of NaNbO3 NPs or NRs in YBCO nanocomposite resulted in a significant increase of ~2.6 times in the critical current density as compared to pure YBCO. In comparison to NRs added YBCO nanocomposite samples, NPs added YBCO nanocomposite samples showed higher improvement. Throughout the entire investigated range of applied field, the maximum pinning force was found for 0.5 wt% NPs added composite sample. 相似文献
2.
《Ceramics International》2021,47(23):32685-32698
Three dimensional (3D) plasmonic nanostructures composed of silver nanoparticles decorated ZnO NRs arrays, have been fabricated by a process combining the electrochemical growth of ZnO NRs and further formation of Ag nanoparticles by the solid-state thermal dewetting (SSD) process. The effect of SSD parameters on the morphological, structural and optical properties of the Ag NPs decorated ZnO NRs arrays has been investigated. It is possible to tune the bandgap of the Ag NPs@ZnO nanorods array 3D plasmonic nanostructure by tailoring the Ag nanoparticle sizes, allowing light manipulation at the nanoscale. The silver nanoparticles attached to the ZnO NRs arrays experienced surface plasmonic coupling effect, causing enhancement in the room temperature photoluminescence (PL) UV emission and quenching the corresponding visible light one. An enhancement in the near band edge emission PL intensity of ZnO to the deep level emission PL intensity ratio after Ag NPs decoration of the ZnO nanostructures corresponding to ca. 11 folds has been observed, indicating that the defect emission is obviously suppressed. 相似文献
3.
J. P. Kar S. N. Das S. W. Lee M. H. Ham J. H. Choi 《Chemical Engineering Communications》2013,200(9):1130-1138
ZnO nanorods (NRs) were hydrothermally synthesized by using equimolar zinc nitrate hydrate (Zn(NO3)2 [sdot] 6H2O) and hexamethylenetetramine (C6H12N4) solutions. The shape of the nanostructures, obtained by aqueous method, was greatly influenced by the growth temperature and the molar concentrations. NRs grown at higher temperature (90°C) have rounded tips, whereas nanostructures of hexagonal flat-end shape were obtained at 75°C. Hardly any nanostructures were observed by further reducing the temperature to 60°C. In addition, solutions with higher molarity favored the appearance of nanoflowers. Scattered ZnO NRs were observed on silicon substrate, whereas aligned ZnO nanowires (NWs) 50–70 nm in diameter were obtained at 75°C by introducing sputtered ZnO film as a seed layer. High-resolution transmission electron microscopy (HRTEM) confirmed the growth of ZnO nanowires along [001] direction. A band-edge luminescence along with a broad visible spectrum was observed for the ZnO nanowires. 相似文献
4.
Ali Can Güler Jan Anto Milan Masa Michal Urbnek Michal Machovský Ivo Kuitka 《International journal of molecular sciences》2023,24(1)
Band bending modification of metal/semiconductor hybrid nanostructures requires low-cost and effective designs in photoelectrochemical (PEC) water splitting. To this end, it is evinced that gradient doping of Au nanoparticles (NPs) inwards the ZnO nanorods (NRs) through thermal treatment facilitated faster transport of the photo-induced charge carriers. Systematic PEC measurements show that the resulting gradient Au-doped ZnO NRs yielded a photocurrent density of 0.009 mA/cm2 at 1.1 V (vs. NHE), which is 2.5-fold and 8-fold improved compared to those of Au-sensitized ZnO and the as-prepared ZnO NRs, respectively. The IPCE and ABPE efficiency tests confirmed the boosted photoresponse of gradient Au-incorporated ZnO NRs, particularly in the visible spectrum due to the synergistic surface plasmonic effect of Au NPs. A gradient Au dopant profile promoted the separation and transfer of the photo-induced charge carriers at the electrolyte interface via more upward band bending according to the elaborated electrochemical impedance spectroscopy and Kelvin probe force microscopy analyses. Therefore, this research presents an economical and facile strategy for preparing gradient plasmonic noble NP-incorporated semiconductor NRs, which have excellent potential in energy conversion and storage technologies. 相似文献
5.
Neazar Baghdadi Numan Salah Ahmed Alshahrie A.R. Ansari Kunihito Koumoto 《Ceramics International》2021,47(5):6169-6178
At present, huge research efforts are dedicated to improve the efficiency of thermoelectric (TE) materials. Nanostructuring is one of the suggested methods to improve their TE performance. However, the morphology of a nanomaterial might play a significant role on its TE properties. In this work, we demonstrated this effect by producing zinc oxide (ZnO) in two different morphologies using the microwave assisted chemical route. Nanoparticles (NPs) and nanorods (NRs) were synthesised by changing the molar ratios of the starting precursors. The obtained results show that the NRs have improved TE properties compared to those of the NPs, particularly at high temperature. At 673 K the Seebeck coefficient, electrical conductivity and power factor values of the ZnO NRs reached ?1020 μV/K, 22 S/m and 23 μW/m.K2, respectively. The NPs have only recorded ?850 μV/K, 3 S/m and 2.4 μW/m.K2 of these factors. Moreover, the thermal conductivity of the NRs was found to be three times lower than that of the NPs. As a result of these differences the Figure of Merit (zT) value of the NRs is around 0.012, while that of the NPs is only 0.001. Power generation characteristics of single leg modules made of the ZnO NPs and NRs, measured under the conditions of actual applications in an air atmosphere were also investigated. The output power of the ZnO NRs is found to be several times higher than that of the NPs. These results have clearly demonstrated the effect of nanostructures morphology on the TE performance, which might be important for future TE generators. 相似文献
6.
In this paper we report the zinc oxide nanorods (ZnO NRs) growth by electrochemical deposition onto polycrystalline gold electrodes modified with assemblies of polystyrene sphere monolayers (PSSMs). Growth occurs through the interstitial spaces between the hexagonally close packed spheres. ZnO NRs nucleate in the region where three adjacent spheres leave a space, being able to grow and projected over the PSSMs. The nanorod surface density (NNR) shows a linear dependence with respect to a PS sphere diameter selected. XRD analysis shows these ZnO NRs are highly oriented along the (0 0 2) plane (c-axis). This open the possibility to have electronic devices with mechanically supported nanometric materials. 相似文献
7.
Undoped and group-I elements doped ZnO nanoparticles (NPs) (Zn1?yX2yO, X=Li, Na, K, and y=0.05) were synthesized by a sol–gel method. Structural and morphological studies of the resulting products were carried out by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The XRD results revealed that the sample products were crystalline with a hexagonal wurtzite phase. The TEM images showed ZnO NPs with nearly spherical shapes with particle size distributed over the nanometer range. In addition, the XRD and TEM results showed a decrease in crystallite and particle sizes of NPs from Li-doped to K-doped ZnO NPs. Crystalline development in the ZnO NPs was investigated by X-ray peak broadening. The size-strain plot (SSP) method was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of the undoped and doped ZnO NPs. The effect of doping on the optical band-gap and crystalline quality was also investigated by using photoluminescence (PL) and Raman spectrometers. The Raman spectra of the all ZnO NPs showed a strong E2(high) peak. The PL spectra exhibited a strong peak in the ultraviolet (UV) region of the electromagnetic spectrum for the all ZnO NPs. The UV peak of the doped ZnO NPs was red-shifted with respect to that of the undoped ZnO NPs. 相似文献
8.
《Ceramics International》2017,43(8):5934-5940
This paper reports a facile two-step synthesis route for the preparation of flower-like ZnO/α-Fe2O3 nanorods (NRs). Flower-like ZnO NRs with the average diameter about 810 nm and length about 4.5 µm were firstly synthesized via a chemical solution method, and then ZnO NRs was coated with a continuous α-Fe2O3 layer to form ZnO/α-Fe2O3 core-shell structure through an ionic-layer adsorption and reaction method. The gas-sensing results show that the ZnO/α-Fe2O3 NRs exhibit excellent sensitivity, selectivity, and response-recovery capacity to ethanol vapor at a low optimum temperature of 240 °C. In particular, compared with pure ZnO NRs and α-Fe2O3 nanoparticles (NPs), the ZnO/α-Fe2O3 NRs show an obvious improvement in gas sensing properties. The substantial improvement of sensing properties may be attributed to the unique microstructure and heterojunction formed between ZnO and α-Fe2O3. 相似文献
9.
Musbah Babikier Dunbo Wang Jinzhong Wang Qian Li Jianming Sun Yuan Yan Qingjiang Yu Shujie Jiao 《Nanoscale research letters》2014,9(1):199
Cu-doped ZnO nanorods have been grown at 90°C for 90 min onto a quartz substrate pre-coated with a ZnO seed layer using a hydrothermal method. The influence of copper (Cu) precursor and concentration on the structural, morphological, and optical properties of ZnO nanorods was investigated. X-ray diffraction analysis revealed that the nanorods grown are highly crystalline with a hexagonal wurtzite crystal structure grown along the c-axis. The lattice strain is found to be compressive for all samples, where a minimum compressive strain of −0.114% was obtained when 1 at.% Cu was added from Cu(NO3)2. Scanning electron microscopy was used to investigate morphologies and the diameters of the grown nanorods. The morphological properties of the Cu-doped ZnO nanorods were influenced significantly by the presence of Cu impurities. Near-band edge (NBE) and a broad blue-green emission bands at around 378 and 545 nm, respectively, were observed in the photoluminescence spectra for all samples. The transmittance characteristics showed a slight increase in the visible range, where the total transmittance increased from approximately 80% for the nanorods doped with Cu(CH3COO)2 to approximately 90% for the nanorods that were doped with Cu(NO3)2. 相似文献
10.
The present work takes advantage of green electrospinning to create novel composite multifunctional nanofibers (NFs) bearing inorganic nanoparticles (NPs), more specifically quantum dots (QDs), cerium oxide nanoparticles (CeO2 NPs) and iron oxide nanoparticles (Fe3O4 NPs). This is achieved by first encapsulating the desired inorganic NPs into polymer particles by the use of miniemulsion polymerization, and second, spinning the hybrid polymer particles using polyvinyl alcohol (PVA) as template polymer. It is proved that using green electrospinning, it is not only possible to ensure an excellent distribution and encapsulation of the inorganic NPs along the NFs, but also allows to control and change the concentration, size, and type of the inorganic NPs without altering the NFs size, a fact that is not possible by conventional solution electrospinning. As proof of concept, NFs with up to three different types of inorganic NPs have been created in a single electrospinning step, but this technology allows to incorporate as much inorganic NPs as desired without altering the NFs morphology and ensuring a good distribution and encapsulation of the NPs. This paper demonstrates that green electrospinning is a powerful and attractive technology to create multifunctional NFs that are promising materials for sensing and biomedical applications. 相似文献
11.
《Ceramics International》2022,48(10):13452-13463
The development of targeted drug delivery systems with controlled drug release and enhanced drug bioavailability has attracted increasing attention as a candidate for clinical applications. We designed biocompatible citrate-functionalized hydroxyapatite nanorods (Cit-HAp NRs) loaded with artesunate (ART) for use in colon cancer therapies. These were then encapsulated into surfactant free PLGA nanoparticles (ART@Cit-HAp NRs/SF-PLGA NPs). The synthesized Cit-HAp NRs, ART-loaded Cit-HAp NRs and ART@Cit-HAp NRs/SF-PLGA NPs were characterized using a variety of comprehensive techniques. An ART loading efficiency of ~92% was observed upon using a 1:10 mass ratio (ART: Cit-HAp NRs). We revealed that the adsorption of ART on Cit-HAp NRs proceeds via a pseudo-second-order adsorption mechanism. The in vitro ART release from the nanocomposites (ART@Cit-HAp NRs/SF-PLGA NPs) exhibits a pH dependent release and the rate of ART release from the ART@Cit-HAp NRs/SF-PLGA NPs was slower than the release from Cit-HAp NRs. The effects of ART@Cit-HAp NRs/SF-PLGA NPs were evaluated in human colon cancer (HCT 116 and Caco-2) cell lines. ART@Cit-HAp NRs/SF-PLGA NPs demonstrated higher anti-proliferation activity compared with free ART. The delivery of ART using Citrate-functionalized hydroxyapatite encapsulated, surfactant free PLGA nanoparticles as a carrier could improve their anti-cancer activities. 相似文献
12.
Dong Hyuk Youn Ngoc Minh Tran Thanh Nhan Nguyen Sung Min Cho Harry Jung Aran Lee Jinhee Kim Nayoung Kim Jin Pyeong Jeon Hyojong Yoo 《Journal of the American Ceramic Society》2023,106(12):7218-7229
The design and optimization of nanostructures with unique morphologies and properties are at the forefront of biomedical nanotechnology. Cerium oxides are widely used to investigate the effect of morphology on performance. However, elucidating the morphology–activity relationship of cerium oxide nanocrystals in biomedical applications remains challenging. Herein, the therapeutic effects of cerium oxide nanoparticles with different morphologies: cerium oxide nanorods with two different aspect ratios (CeOx NRs_A and CeOx NRs_B), cerium oxide nanopolyhedra (CeOx NPs), and cerium oxide nanocubes (CeOx NCs) are investigated in in vivo and in vitro mild traumatic brain injury (TBI) models. Cerium oxide nanoparticles inhibit oxidative stress and inflammation after mild TBI, alleviating cognitive impairment; furthermore, the therapeutic effect is significantly affected by their morphology. Owing to the higher Ce3+/Ce4+ ratio, exposure of more active crystal surfaces, and greater number of exposed oxygen vacancies, CeOx NRs show better activity than CeOx NPs and CeOx NCs for mild TBI. Among the two investigated types of cerium oxide nanorods, CeOx NRs_A, with a higher Ce3+/Ce4+ ratio on the surface, appear to spread better than CeOx NRs_B in the injured lesions. The factors causing morphology-controlled biomedical performance, such as Ce3+/Ce4+ molar ratio, surface area, and aspect ratio, are discussed. 相似文献
13.
Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO. 相似文献
14.
《Ceramics International》2016,42(11):13215-13222
Herein, we report the facile growth of ZnO nanoflowers composed of nanorods on silicon substrate by non-catalytic thermal evaporation process. The grown nanoflowers were examined in terms of their morphological, structural, optical and field emission properties. The detailed characterizations revealed that the nanoflowers are grown in high density, possessing well-crystallinity and exhibiting wurtzite hexagonal phase. The Raman-scattering spectrum shows a sharp optical-phonon E2 mode at 437 cm−1 which confirmed the wurtzite hexagonal phase for the grown nanoflowers. The room-temperature PL spectrum depict a strong ultraviolet emission at 381 nm, revealed good optical properties for the ZnO nanoflowers. The field emission studies revealed that a turn-on field for the ZnO nanoflowers based field emission device was 4.3 V/μm and the emission current density reached to 0.075 mA/cm2 at an applied electric field of 7.2 V/μm and exhibit no saturation. The field enhancement factor ‘β’ for the fabricated device was estimated from the F-N plot and found to be ~2.75×103. Finally, systematic time-dependent experiments were performed to determine the growth process for the formation of ZnO nanoflowers composed of nanorods. 相似文献
15.
Sara Khosravi-Gandomani Ramin Yousefi Farid Jamali-Sheini Nay Ming Huang 《Ceramics International》2014
Zn1−xAgxO nanoparticles (NPs) (x=0, 0.02, 0.04, and 0.06) were synthesized by a sol–gel method. The synthesized undoped ZnO and Zn1−xAgxO-NPs were characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and UV–visible spectroscopy. The XRD patterns indicated that undoped and Ag-doped ZnO crystallize in a hexagonal wurtzite structure. The TEM images showed ZnO NPs with nearly spherical shapes, with particle size distributed over the nanometer range. Evidence of dopant incorporation is demonstrated in the XPS measurements of the Ag-doped ZnO NPs. The Raman measurements indicated that the undoped and Ag-doped ZnO-NPs had a high crystalline quality. From the result of UV–vis, the band-gap values of prepared undoped and Ag-doped ZnO were found to decrease with an increase in Ag concentration. The obtained undoped and Ag-doped ZnO nanoparticles were used as a source material to grow undoped and Ag-doped ZnO nanowires on n-type Si substrates, using a thermal evaporation set-up. Two probe method results indicated that the Ag-doped ZnO nanowires exhibit p-type properties. 相似文献
16.
Joselito P. Labis Anwar Q. Al-Anazi Hamad A. Al-Brithen Mahmoud Hezam Mohammad Abdulaziz Alduraibi Ahmad Algarni Abdulaziz A. Alharbi Abdulrhman S. Al-Awadi Aslam Khan Ahmed Mohamed El-Toni 《Journal of the American Ceramic Society》2019,102(7):4367-4375
In this study, pulsed laser ablation technique, also known as pulsed laser deposition (PLD), is used to design and grow zinc oxide (ZnO) nanostructures (nanoworms, nanowalls, and nanorods) by template/seeding approach for gas-sensing applications. Conventionally, ZnO nanostructures used for gas-sensing have been usually prepared via chemical route, where the 3D/2D nanostructures are chemically synthesized and subsequently plated on an appropriate substrate. However, using pulsed laser ablation technique, the ZnO nanostructures are structurally designed and grown directly on a substrate using a two-step temperature-pressure seeding approach. This approach has been optimized to design various ZnO nanostructures by understanding the effect of substrate temperature in the 300-750°C range under O2 gas pressure from 10-mTorr to 10 Torr. Using a thin ZnO seed layer as template that is deposited first at substrate temperature of ~300°C at background oxygen pressure of 10 mTorr on Si(100), ZnO nanostructures, such as nanoworms, nanowalls, and nanorods (with secondary flower-like growth) were grown at substrate temperatures and oxygen background pressures of (550°C and 2 Torr), (550°C and 0.5 Torr), and (650°C and 2 Torr), respectively. The morphology and the optical properties of ZnO nanostructures were examined by Scanning Electron Microscope (SEM-EDX), X-ray Diffraction (XRD), and photoluminescence (PL). The PLD-grown ZnO nanostructures are single-crystals and are highly oriented in the c-axis. The vapor-solid (VS) model is proposed to be responsible for the growth of ZnO nanostructures by PLD process. Furthermore, the ZnO nanowall structure is a very promising nanostructure due to its very high surface-to-volume ratio. Although ZnO nanowalls have been grown by other methods for sensor application, to this date, only a very few ZnO nanowalls have been grown by PLD for this purpose. In this regard, ZnO nanowall structures are deposited by PLD on an Al2O3 test sensor and assessed for their responses to CO and ethanol gases at 50 ppm, where good responses were observed at 350 and 400°C, respectively. The PLD-grown ZnO nanostructures are very excellent materials for potential applications such as in dye-sensitized solar cells, perovskite solar cells and biological and gas sensors. 相似文献
17.
《Ceramics International》2022,48(7):9229-9238
Controllable assembly from one-dimensional (1-D) and two-dimensional (2-D) nanoscale structures to three-dimensional (3-D) complex nanostructures has attracted great interest. For the first time, nanorods and nanosheets were controllably assembled into 3-D SnO2 nanoflower architectures based on a facile and shape-controlled acid vapor oxidation (AVO) method from the substrate in a simple reaction system. The as-prepared 3-D SnO2 nanoflowers have diameters ranging from 625 to 875 nm and are self-assembled by many nanorods and nanosheets with diameters and thicknesses of 33 nm. The growth of SnO2 with different morphologies was studied by controlling the reaction temperature and hydrochloric acid concentration. Their application in gas sensing was evaluated, indicating that the 3-D SnO2 nanoflower-based sensor is ultrasensitive to ethanol with a response of 2.54–50 ppb at the optimal working temperature of 230 °C. This work offers a facile, shape-controlled, and efficient route to synthesize complex SnO2 nanoflowers for gas detection with high performance, including ultrahigh sensitivity, good selectivity, and reversibility. 相似文献
18.
Sumetha Suwanboon Pongsaton AmornpitoksukPhuwadol Bangrak 《Ceramics International》2011,37(1):333-340
Zn1−xTixO (x = 0, 0.01, 0.03 and 0.05) nanoparticles were prepared by high-energy ball milling at 400 rpm. The milled powders were characterized by X-ray diffractometer (XRD) and the results exhibited that Ti-doped ZnO nanoparticles consisted of single phase with hexagonal structure when the mixtures of ZnO and TiO2 powders were milled for 20 h. The crystallite size reduced as a function of the doping content and milling time from 1 to 10 h then increased after milling for 20 h and when the annealing temperature increased. The strain changed inversely to the crystallite size. A wider band-gap was obtained by increasing the doping content and annealing temperature because of a reduction in defect concentration. Both ZnO- and Ti-doped ZnO nanoparticles caused damage to S. aureus, E. coli, P. mirabilis, S. typhi and P. aeruginosa. 相似文献
19.
This paper firstly reports on a series of nanocomposite thin films composed of a ferroelectric Bi3.6Eu0.4Ti3O12 (BET) and Au-decorated ZnO nanorods (Au-ZnO), which are prepared by a ultraviolet-induced hybrid chemical solution method. The effects of Au nanoparticles (NPs) and ZnO nanorods on the significantly red photoluminescence enhancement of Eu3+ ions are investigated. The results indicate that the larger near band edge (NBE) emission of ZnO by the SPR effect of Au NPs can make an energy transfer from ZnO to Eu3+ ions. Simultaneously, the depression of the deep-level emission of ZnO can improve the monochromaticity in the visible range. Furthermore, the dielectric and ferroelectric properties of the thin films are also enhanced. The findings suggest that the nanocomposite thin films of a ferroelectric BET and Au-ZnO could be used as a multifunctional material in the ferroelectric optoelectronic devices with bright light emitting. 相似文献
20.
In the present work, the effects of two different morphologies of zinc oxide nanoparticles (nanosheets and nanorods) were investigated by in-situ measurement of deposition weight, and current density. ZnO nanosheets and nanorods were synthesized by microwave-assisted method using co-surfactant route. The average thickness of obtained nanosheets, and the average diameter of nanorods were measured to be about 26 nm and 139 nm, respectively. ZnO films were obtained by electrophoretic deposition from suspension of nanoparticles in ethanol under different voltages. Results indicated that ZnO nanosheets tend to have greater deposition rate than ZnO nanorods under similar conditions. The compactness of the film obtained from nanosheet suspension was higher than the one obtained from nanorod suspension. However, the film obtained from ZnO nanorods displayed more uniformity at different voltages in comparison to the film obtained from ZnO nanosheets, which can be due to different active surface area, and also different way of motion under hydrodynamic forces in the suspension. 相似文献