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1.
In this paper the synthesis of SnO2 nanoparticles with average particle size up to about 70 nm using SnCl22H2O and NH4OH in 1‐botanol solution by the precipitation method is reported and the inhibition of sodium dodecyl sulphate (SDS) on the SnO2 particle growth is investigated by soaking SnO2precursor in the SDS solution for 24 h. The as‐prepared SnO2and SDS modified‐SnO2 powders, then, were calcined at different temperatures and the X‐ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT‐IR) were used to characterize the output samples. The XRD results reveal that the structure of tin‐dioxide is tetragonal rutile and the as‐prepared SnO2 nanoparticles grow with increasing the annealing temperature, while the SDS treatment prevents the particle growth under the same condition. Furthermore, the FT‐IR results indicate the formation of tin‐hydroxyl group which are then converted into tin‐dioxide with heat treatment. Further characterization of the samples by the transmission electron microscopy (TEM) and the photoluminescence (PL) spectroscopy was carried out. The room temperature PL spectra of SnO2exhibits broad and strong peak attributed to the surface defects such as oxygen vacancies and intensity of which decreases with the increase in particle size. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

2.
Nd‐doped ZnO nanoparticles with different concentration were synthesized by sol‐gel method. The structures, magnetic and optical properties of as‐synthesized nanorods were investigated. X‐ray diffraction (XRD) and x‐ray photoelectron spectroscopy (XPS) results demonstrated that Nd ions were incorporated into ZnO lattice; but Zn1‐xNdxO nanoparticles with Nd concentration of x = 0.05 showed Nd2O3 phase, so the saturation concentration of Nd in Zn1‐xNdxO is less than 5 at%. Vibrating sample magnetometer (VSM) measurements indicated that Nd doped ZnO possessed dilute ferromagnetis behaviour at room temperature. Photoluminescence spectroscopy (PL) showed that Nd ions doping induced a red slight shift and decrease in UV emission with increase of Nd concentration.  相似文献   

3.
L‐Phenylalanine (C9H11NO2), having the morphology of spherulitic needles, an amino acid constituent, responsible for brain nutrition is crystallized in silica gel of pH 6.0 by single diffusion method in a period of 30 minutes. The grown crystals were characterized by X‐ray powder diffraction, Fourier Transform infrared spectroscopy and Visible Ultraviolet spectroscopy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
In this paper, we report a synthesis, characterization and electrochemical properties of V2O5 nanobelts. V2O5 nanobelts have been prepared via hydrothermal treatment of commercial V2O5 in acidic (HCl/H2SO4) medium at relatively low temperature (160 °C). The hydrothermally derived products have been characterized by powder X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), Raman spectroscopy, X‐ray photo electron spectroscopy (XPS), UV‐Vis spectroscopy, Scanning/Transmission electron microscopy (SEM/TEM). XRD pattern of V2O5 nanobelts show an orthorhombic phase. From the FTIR spectrum, the peak observed at 1018 cm−1 is characteristic of the stretching vibration mode of the terminal vanadyl, V = O. The UV‐Vis absorption spectrum of V2O5 nanobelts show maximum absorbance at 430 nm, which was blue‐shifted compared to that of bulk V2O5. TEM micrographs reveal that the products consist of nanobelts of 40‐200 nm in thickness and several tens of micrometers in length. The electrochemical analysis shows an initial discharge capacity of 360 mAh g−1 and its almost stabilized capacity is reached to 250 mAh g−1 after 55 cycles. A probable reaction mechanism for the formation of orthorhombic V2O5 nanobelts is proposed.  相似文献   

5.
MgO nanorods were grown by the thermal evaporation of Mg3N2 powders on the Si (100) substrate coated with a gold thin film. The MgO nanorods grown on the Si (100) substrate were a few tens of nanometers in diameter and up to a few hundreds of micrometers in length. MgO/SiO2 core‐shell nanorods were also fabricated by the sputter‐deposition of SiO2onto the MgO nanorods. Transmission electron microscopy (TEM) and X–ray diffraction (XRD) analysis results indicated that the cores and shells of the annealed core‐shell nanorods were a face‐centered cubic‐type single crystal MgO and amorphous SiO2, respectively. The photoluminescence (PL) spectroscopy analysis results showed that SiO2 coating slightly decreased the PL emission intensity of the MgO nanorods. The PL emission of the MgO/SiO2 core‐shell nanorods was, however, found to be considerably enhanced by thermal annealing and strongly depends on the annealing atmosphere. The PL emission of the MgO/SiO2 core‐shell nanorods was substantially enhanced in intensity by annealing in a reducing atmosphere, whereas it was slightly enhanced by annealing in an oxidative atmosphere. The origin of the PL enhancement by annealing in a reducing atmosphere is discussed with the aid of energy‐dispersive X‐ray spectroscopy analyses. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

6.
Large single crystals of lanthanide hydroxides [Ln(OH)3 (Ln = La, Pr, Nd, Sm, Eu and Tb)] up to several millimeters have been grown by using solid KOH assisted hydrothermal method. Eu(OH)3 samples, as a representative of the Ln(OH)3 crystals, were characterized by X‐ray diffraction (XRD), 4‐circle single‐crystal diffraction, Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). FESEM image shows hexagonal prism morphology for the Eu(OH)3 large crystals. Research on the photoluminescence and magnetic properties of Eu(OH)3 species was conducted.  相似文献   

7.
A novel high‐efficiency photoelectrode (Fe2O3/reduced graphene oxide/CdS) built from heterostructure and conductive scaffold has been successfully designed and synthesized. Reduced graphene oxide works as a “bridge” which benefits for electron and hole transport. The obtained heterostructure photoelectrodes were systematically characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, and X‐ray photoelectron spectroscopy (XPS). The photoconversion efficiency (η) and photocurrent densities vs. time (I‐t) curves responding to monochromatic lights have been further investigated in‐depth, which reveals that introduction of CdS and reduced graphene oxide played an important role in the enhancement of photoelectrochemical performance.  相似文献   

8.
Bis(isothiocyanato)‐bis(4‐methylpyridine)zinc(II)(Zn(SCN)2(C6H7N)2), (abbreviated as ZBNC) single crystals of optical quality have been grown from acetone solution by the slow temperature‐lowering method. Its solubilities at different temperatures in acetone were measured. The X‐ray powder diffraction (XRPD) spectroscopy of ZBNC crystal was performed at room temperature. The second harmonic generation (SHG) efficiency was determined by powder technique of Kurtz and Perry using Nd:YAG laser, which is equivalent to KDP crystal. The thermal decomposition process was characterized by thermal gravity and differential thermal analysis (TG\DTA). The specific heat of the crystal is 1440.67 J/mol·K at 325 K. The IR spectrum was recorded in the 500∼3500 cm–1 region, using KBr pellets on a Nicolet 170sx FT‐IR spectrometer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

9.
A facile route to prepare lithium niobate (LiNbO3) powders was proposed by an alternative solid‐state method. Stoichiometric Li2C2O4 and ammonium niobium oxalate were mixed with small amounts of water and then dried at room temperature. It was demonstrated that Li[NbO(C2O4)2n H2O intermediate was produced by an ion‐exchange reaction. Pure LiNbO3 powders were successfully synthesized by heating the intermediate at 500, 600 and 700 °C for 3 h. X‐ray diffraction (XRD), scanning electron microscopy (SEM), Fourier‐transform infrared (FTIR) spectroscopy, UV‐Vis diffuse reflectance (UV‐Vis) spectroscopy and thermogravimetric (TG) analysis were used to characterize the precursor compound and as‐prepared samples. XRD results reveal that all the products are identified as hexagonal structure with high relative crystallinity (>87%). The particle size is found to be about 40 nm for the mixture calcined at 500 °C according to XRD data, which is in good agreement with SEM data. The as‐prepared LiNbO3 powders by this method are high quality according to FTIR spectra. (Li0.996Nb0.005)Nb0.999O3 phase was formed when the calcination temperature was raised to 800 °C. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

10.
Thin polycrystalline diamond films were synthesized on silicon substrate by Hot Filament Chemical Vapor Deposition (HF CVD) technique from a mixture of hydrogen and different content of methyl alcohol. A comparative study on the Electron Paramagnetic Resonance (EPR), Raman spectroscopy and Scanning Electron Microscopy (SEM) were performed. It was shown that EPR signal, Raman spectra and morphology, studied by SEM, strongly depend on the ratio of CH3OH/H2 in the HF CVD reactor. The peak‐to‐peak line‐width in EPR signal varies from 0.09 to 0.8 mT depending on diamond quality. The Raman spectra of our diamond film showed, except well defined diamond Raman lines positioned at 1332 cm‐1 with different Full Width at Half Maximum (FWHM), a broad band having maximum at around 1530 cm‐1 which is characteristic for amorphous carbon phase. The obtained results show that EPR, SEM and Raman spectroscopy yield complementary results about the defects present in CVD diamond films. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

11.
Cd1‐xMnxTe (x =0.2, CdMnTe) crystal was grown by the vertical Bridgman method, which exhibits a pure zincblende structure in the whole ingot. The major defect, twins, which is fatal to CdMnTe crystal, was analyzed with scanning electron microscopy (SEM), X‐ray energy disperse spectroscopy (XEDS) and optic microscopy on the chemical etching surface. The twins observed in the as‐grown ingot are mainly lamellar ones, which lie on the {111} faces from the first‐to‐freeze region of the ingot and run parallel to the growth axis of the ingot. Coherent twins with {115}t‐{111}h orientations when indexed with respect to both the twin and host orientations, are often found to be terminated by {110}t‐{114}h lateral twins. Te inclusions with about 20 μm in width are observed to preferentially decorate the lamellar twin boundaries. The origin of the twins, relating to the growth twin and the phase transformation twin, is also discussed in this paper. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

12.
CdO nanowires were produced by calcination process using Cd(OH)2nanowires as precursors. The Cd(OH)2 nanowires were synthesized via arc discharge method submerged in de‐ionized water. Transmission electron microscopy (TEM) analysis of the as‐synthesized Cd(OH)2 nanowires revealed that nanowire morphology was abundant form with the diameters range from 5 to 40 nm. In addition to the nanowire morphology, Cd(OH)2 nanospheres and hexagonal shaped nanoparticles were also displayed. The Cd(OH)2 nanostructures were used as precursors to produce CdO nanowires and calcinated in air at 400 °C for four hours. After calcination, the structural, morphological and optical properties of the as‐synthesized CdO nanowires were characterized by means of TEM, selected area electron diffraction (SAED), X‐ray diffraction (XRD) and UV‐vis spectroscopy. The XRD and SAED techniques showed that the as‐synthesized Cd(OH)2 nanostructures could be transformed into CdO nanostructures after the calcination process. TEM results revealed that the as‐synthesized CdO nanowires were 5–30 nm in diameter and shorter than corresponding Cd(OH)2 nanowires. In addition, the diameters of the spherical or irregular CdO nanoparticles ranged from 20 nm to 50 nm. UV‐vis spectroscopy analysis was showed that the direct gap of the CdO nanowires were found to be 2.60 eV which is slightly higher than the earlier reported values of the bulk CdO for direct band gaps (2.3 eV) due to quantum size effect. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

13.
In this article, diaquatetrakis (thiocyanato) manganese(II) mercury(II)‐N‐methyl‐2‐pyrrolidone, MnHg(SCN)4(H2O)2.2(C3H6CONCH3), (abbreviated as MMTWMP), a new organometallic nonlinear optical crystal material is reported. The structure, optical and thermal characterizations were determined by elemental analysis, infrared and Raman spectroscopy, X‐ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, special heat, SHG measurements and UV/Vis/NIR optical transmission spectra. It belongs to the tetragonal crystallographic system, with cell parameters: a = 12.1294, c = 8.2238Å, V = 1211.27Å3. Single crystals with dimensions up to 8 × 7 × 5 mm3 have been obtained. The morphology of the crystals was indexed. The MMTWMP crystal exhibits good physicochemical stability at normal temperature and pressure. Its UV transparency cutoff is 360 nm, which is shifted to the violet by 13 nm, as compared with MnHg(SCN)4 (MMTC); the optical transmission is 44.82% at 404 nm, which is by 17.46% higher than that of MMTC.  相似文献   

14.
The coloration and oxygen vacancies in 0.65Pb(Mg1/3Nb2/3)O3‐0.35PbTiO3 (PMN‐PT(65/35)) (starting composition) single crystals grown by a so‐called modified Bridgman technique were investigated in this paper. Light yellow and dark brown colored crystals were generally observed for the typical as‐grown PMN‐PT(65/35) single crystals. X‐ray diffraction results demonstrated that they were both of pure perovskite structure, but good electric properties were only obtained for the light yellow crystal. X‐ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of its components. The O 1s photoelectron spectra of the dark brown colored crystals located at the higher binding energy side, which meant the existence of the more oxygen vacancies. It accordingly led to the formation of the low valence cations associated with the coloration of the crystals, which is also testified by the obtained X‐ray photoelectron spectra of Ti and Nb. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

15.
L‐Valinium picrate (C5H12NO2)+. (C6H2N3O7), a non‐linear optical material from the amino acid family which has large second harmonic generation (SHG) efficiency, was grown by slow evaporation method. Characterization of the crystals was made using single crystal X‐ray diffraction. The functional groups and the modes of vibrations were found by using the Fourier transform infrared (FTIR) spectroscopy. The second harmonic generation (SHG) conversion efficiency was investigated using the Kurtz and Perry method. The SHG conversion efficiency is 60 times higher than that of the standard KDP and 8 times higher than that of the standard Urea and the optical transparency was analyzed using UV‐visible‐NIR absorption spectrum. The structural features of the material leading to the large SHG efficiency are discussed. Microhardness and dielectric studies were also carried out. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

16.
Unfilled and ytterbium (Yb)‐filled cobalt antimony (CoSb3) nanoparticles were synthesized via solvothermal route using sodium borohydride (NaBH4) as a reducing agent. The effect of various amounts of sodium borohydride on the formation of as‐synthesized CoSb3 nanoparticles with pure phase was investigated. It is found that a sufficient amount of NaBH4 was required in order to form pure phase CoSb3. In addition, the effect of annealing time and temperature on the phase transformation of the as‐prepared non‐pure phase CoSb3 sample was also investigated. It is found that annealing at 500 °C for 5 h would eliminate those non‐CoSb3 phases and result in pure cubic skutterudite phase CoSb3. Structural characterization of the as‐prepared unfilled and Yb‐filled nanoparticles was carried out with transmission electron microscopy (TEM) which revealed the formation of highly crystalline cubic phase of skutterudite Yb‐filled CoSb3. Laser induced breakdown spectroscopy (LIBS) confirmed the presence of ytterbium in the Yb‐filled CoSb3 samples.  相似文献   

17.
Elliptic NdCrO3 microplates were synthesized by a simple and facile one‐step hydrothermal method of processing temperature 280 °C for 3 days. The products prepared in this paper have been characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), X‐ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR) and field‐emission scanning electron microscopy (FESEM). The magnetic properties of the final sample are also studied. The XRD pattern indicates the pure orthorhombic phase for NdCrO3 particles, the XPS, XRF and FTIR results further demonstrate the composition and purity of the final product. A possible growth mechanism for elliptic NdCrO3 microplates is proposed. Through the investigation of magnetic properties, it can be generally concluded that the orthorhombic elliptic NdCrO3 microplates exhibit typical behaviors of magnetic transition, spin reorientation transition and magnetic exchange bias. The Néel temperature is 218 K and the spin reorientation transition temperature is 46 K. The hysteresis loop under 5 K shows that the value of exchange bias field (Hex) is 12 Oe and the shift of remanent magnetization (ΔM) is 0.008 emu/g, respectively.  相似文献   

18.
In this paper, strontium carbonate (SrCO3) crystals have been synthesized in the presence of two organic additives, including sodium citrate and hexamethylenetetramine (HMT). Scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, X‐ray powder diffractometry and selected area electron diffraction (SAED) were used to characterize the products. The results indicate that SrCO3rods with the ratio of length to diameter about 20 are obtained in the aqueous solution containing sodium citrate. While polycrystalline SrCO3 hierarchical branches with about 10 μm length are produced by using HMT.The possible formation mechanism of the SrCO3crystals obtained in above two systems is discussed, which can be interpreted by particle‐aggregation based non‐classical crystallization laws. Sodium citrate and HMT may direct the formation of SrCO3 rod‐like or branch‐like structures by adsorbing onto certain facets of SrCO3 crystals. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

19.
Stoichiometric lithium niobate powder which are used as feeding material in near stoichometric LiNbO3 crystal growth have been successfully prepared from commercial niobium hydroxide [Nb(OH)5] and nontoxic DL‐malic acid by a wet chemical method. The synthesis temperature was pre‐determined by the results from thermogravimetric and differential thermal analysis. The structure and morphology of the as‐prepared samples were observed by using the infrared spectroscopy and the scanning electron microscopy. The X‐ray diffraction experiment showed that lithium niobate powder had an ilmenite structure, and its unit cell parameters were calculated to be a = b = 0.5140 nm, c = 1.3738 nm, and V = 0.3144 nm3. The melting point of the synthesized powder is 1239 °C and Curie temperature Tc is 1122 °C. This synthesis method would be helpful to grow the near‐stoichiometric LiNbO3 crystal with double crucible techniques. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

20.
Unusual rhombohedral strontium carbonate (SrCO3) aggregates have been synthesized in situ from strontium nitrate by the slow release of carbon dioxide by alkaline hydrolysis of diethyl carbonate at the water/hexamethylene interface in the presence of cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy, Fourier transform infrared spectroscopy and X‐ray powder diffractometry were used to characterize the products. The results indicate that rhombohedral SrCO3 aggregates are obtained with weaker crystallinity and sizes of several micrometers. The possible formation mechanism of the SrCO3 aggregates at the interface is discussed, which can be interpreted by particle‐aggregation based non‐classical crystallization laws. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

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