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1.
The CaLaGa3O7:Eu3+ phosphor was prepared by a chemical co-precipitation method. Field emission scanning electron microscopy (FE-SEM), laser
particle size analysis, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence (CL) spectra were utilized
to characterize the synthesized phosphor. The results revealed that the phosphor was composed of microspheres with a slight
agglomerate phenomenon and was spherically shaped. The average grain size was about 1.0 μm. Eu3+ ions, as luminescent centers, substituted La3+ ions into the single crystal lattice of CaLaGa3O7 with the sites of Cs. Although the CL spectrum was greatly different from the PL spectrum, it had the strongest red emission corresponding to
the 5D0 →7F2 transition of Eu3+. Under the excitation of UV light (287 nm) and electron beams (1.0–7.0 kV), the chromaticity coordinates of the phosphor
were found to be in the nearly red and orange light regions, respectively. 相似文献
2.
QU Xiaosheng LI Jie WANG Zhiyong WANG Cunxin 《武汉大学学报:自然科学英文版》2007,12(3):511-514
A coordination complex was synthesized from NiCl2 and dipeptide glycylglycine(GG). It was characterized by element analysis, NMR and TG methods, and then was determined to be Ni(C4HsN2O3)2Cl2. Using an isoperibolic reaction calorimeter, the standard molar enthalpy of formation of Ni(GG)2Cl2(solid) has been determined to be -(1 674.66±2.02) kJ · mol^-1 at 298.15 K. 相似文献
3.
Guo-qiang Liu Xi Wang Ya-jie Gao Lei Wen Guang-yin Liu Jian-jie Zheng Peng Cen Ying Li 《矿物冶金与材料学报》2012,19(5):457-460
Spinel compounds LiNi0.5Mn1.3Ti0.2O4 (LNMTO) and Li4Ti5O12 (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively.
The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of
1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g−1 at 0.2C and 118.2 mA·h·g−1 at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively. 相似文献
4.
CHENYanhui ZHANGXingtang XUEZhonghui LIYuncai HUANGYabin DUZuliang LITiejin 《科学通报(英文版)》2005,50(7):618-621
Semiconductor SnO2 nanotube arrays were fabricated by sol-gel method based on highly ordered nanoporous anodic alumina membrane. Their microstructures were characterized by scanning electron microscopy,transmission electron microscopy, selective electron diffraction spectroscopy and X-ray diffraction. Results indicated that SnO2 nanotubes have a thickness of about 20-30 nm,and a diameter of about 100-200 nm. The length of the nanotubes is about 1 μn, XRD and SEDS indicated that these SnO2 nanotubes are polycrystalline. 相似文献
5.
Effect of the synthesis route on the structural and dielectric properties of SrBi<Subscript>1.8</Subscript>Y<Subscript>0.2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>9</Subscript> ceramics 下载免费PDF全文
Mohamed Afqir Amina Tachafine Didier Fasquelle Mohamed Elaatmani Jean-Claude Carru Abdelouahad Zegzouti Mustapha El Hammioui 《矿物冶金与材料学报》2018,25(11):1304-1312
This work is devoted to the synthesis and characterization of yttrium-doped SrBi2Nb2O9 ceramics prepared by three methods: solid state reaction, co-precipitation, and hydrothermal. Multiple characterizations, specifically scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), were used to validate the structural feature. The crystallite size was estimated by Scherrer’s formula and the Williamson–Hall plot. The effect of the process on the band intensities of the FTIR spectra was investigated. The crystallite size and microstructure of ceramics prepared from different synthesis processes were strongly influenced by the sinterability. SEM images revealed nanograin ceramics for materials prepared by co-precipitation and hydrothermal methods and micrograin ceramics prepared by the solid state method. The synthesized compounds underwent phase transitions at 480–465°C. The dielectric and electrical properties of these Y-doped SrBi2Nb2O9 ceramics appear to be dependent on the grain size. 相似文献
6.
To synthesize pure γ-La2S3 at lower temperature, lanthanide complex La(Et2S2CN)3·phen, containing La-S bond, was chosen as the precursors to decompose. The obtained samples were characterized by X-ray power
diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) with an energy dispersive spectrometer and UV-Vis
diffuse reflectance spectra. The decomposition mechanism of the lanthanide complex was studied by thermogravimetric analyses
(TGA). The results show that the obtained samples are cubic phase particles with sizes among 20–50 nm and the band gap is
2.97 eV, which is bigger than that of its bulk crystal. TG/DTG results indicate that La(Et2S2CN)3·phen decomposed to γ-La2S3
via La4(Et2S2CN)3 as an intermediate product. 相似文献
7.
Ta-doped In2O3 transparent conductive oxide films were deposited on glass substrates using radio-frequency (RF) sputtering at 300°C. The
influence of post-annealing on the structural, morphologic, electrical and optical properties of the films was investigated
using X-ray diffraction, field emission scanning electron microscopy, Hall measurements and optical transmission spectroscopy.
The obtained films were polycrystalline with a cubic structure and were preferentially oriented in the (222) crystallographic
direction. The lowest resistivity, 5.1×10−4 Ω cm, was obtained in the film annealed at 500°C, which is half of that of the un-annealed film (9.9×10−4 Ω cm). The average optical transmittance of the films was over 90%. The optical bandgap was found to decrease with increasing
annealing temperature. 相似文献
8.
Qiong Zhang YunQiu He XiaoGang Chen DongHu Hu LinJiang Li Ting Yin LingLi Ji 《科学通报(英文版)》2011,56(3):331-339
TiO2-Graphene Oxide intercalated composite (TiO2-Graphene Oxide) has been successfully prepared at low temperature (80°C) with graphite oxide (GO) and titanium sulfate (Ti(SO4)2) as initial reactants.GO was firstly exfoliated by NaOH and formed single and multi-layered graphite oxide mixture which can be defined as graphene oxide,[TiO]2+ induced by the hydrolysis of Ti(SO4)2 diffused into graphene oxide interlayer by electrostatic attraction.The nucleation and growth of TiO2 crystallites took place at low temperature and TiO2-Graphene Oxide composite was successfully synthesized.Furthermore,the photocatalytic properties of TiO2-Graphene Oxide under the irradiation of UV light were also studied.The results show that the degradation rate of methyl orange is 1.16 mg min-1 g-1(refer to the efficiency of the initial 15 min).Compared with P25 powder,this kind of intercalation composite owns much better efficiency.On the other hand,the reusable properties and stable properties of TiO2-Graphene Oxide intercalated composite are also discussed in this paper.At last,crystalline structure,interface status,thermal properties and microscopic structure of TiO2-Graphene Oxide were characterized by X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),thermogravimetric analysis (TGA),field emission scanning electron microscopy (FESEM) and high-resolution Transmission Electron Microscopy (HRTEM).Also,we have analyzed major influencing factors and mechanism of the composite structures which evidently improve the photocatalytic properties. 相似文献
9.
De-yong Wang Jun Liu Mao-fa Jiang Fumitaka Tsukihashi Hiroyuki Matsuura 《矿物冶金与材料学报》2011,18(6):646-651
Al-Ti-O inclusions always clog submerged nozzles in Ti-bearing Al-killed steel. A typical synthesized Al2TiO5 inclusion was immersed in a CaO-SiO2-Al2O3 molten slag for different durations at 1823 K. The Al2TiO5 dissolution paths and mechanism were revealed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).
Decreased amounts of Ti and Al and increased amounts of Si and Ca at the dissolution boundary prove that inclusion dissolution
and slag penetration simultaneously occur. SiO2 diffuses or penetrates the inclusion more quickly than CaO, as indicated by the w(CaO)/w(SiO2) value in the reaction region. A liquid product (containing 0.7–1.2 w(CaO)/w(SiO2), 15wt%–20wt% Al2O3, and 5wt%–15wt% TiO2) forms on the inclusion surface when Al2TiO5 is dissolved in the slag. Al2TiO5 initially dissolves faster than the diffusion rate of the liquid product toward the bulk slag. With increasing reaction time,
the boundary reaches its largest distance, the Al2TiO5 dissolution rate equals the liquid product diffusion rate, and the dissolution process remains stable until the inclusion
is completely dissolved. 相似文献
10.
In this study,TiO2@MgO core-shell film was obtained by using a simple chemical bath deposition method to coat a thin MgO film around TiO2 nanoparticles. The core-shell configuration was characterized by X-ray diffractometer (XRD),scanning elec-tron microscopy (SEM),energy dispersive X-ray spectroscopy (EDX),and high-resolution transmission electron microscopy (HRTEM). Lattice fringes were observed for the TiO2 particles,and the MgO shell showed an amorphous structure,revealing a clear distinction between the core and shell materials. Applying the core-shell film as photoanode to the dye-sensitized solar cells (DSSCs),it shows a superior performance compared to the pure TiO2 electrode. Under the illumination of simulated sunlight (75 mW-cm-2),the short circuit photocurrent (Jsc),the open circuit photovoltage (Voc),and the fill factor (fF) are 8.80 mA-cm-2,646 mV,and 0.69,respectively,and the conversion efficiency (η) in-creased by 21.8% (from 4.32% to 5.26%) when dipping for opti-mum condition. 相似文献
11.
Preparation and upconversion luminescence of YVO<Subscript>4</Subscript>:Er<Subscript>3+</Subscript>, Yb<Subscript>3+</Subscript> 下载免费PDF全文
YVO4:Er3+, Yb3+ with varying Yb3+ concentrations were prepared by a precipitation method. The results of X-ray diffraction (XRD) show that all the samples
have a tetragonal zircon structure; the calculated average crystallite sizes are in the range of 14–22 nm. The lattice constants
and cell volume of the samples decrease slightly with the increase in Yb3+ concentration. The upconversion luminescence spectra of all the samples were studied under 980 nm laser excitation. The strong
green emission is observed, which is attributed to the 2H11/2 → 4I15/2 and 4S3/2→4I15/2 transitions of Er3+, and the red emission peaks in 650–675 nm can be ignored. The emission intensity for the sample depends on the Yb3+ concentration. These results reveal that the upconversion processes of YVO4:Er3+, Yb3+ are related to the structure and the doping Yb3+ concentration of the sample. 相似文献
12.
ZHAO Lihong TIAN Zhidong TANG Zheng WANG Ziyu ZHU Benpeng WANG Lili XIONG Rui SHI Jing 《武汉大学学报:自然科学英文版》2007,12(6):1039-1042
Polycrystalline samples of a novel spin-liquid compound Tb2Ti2O7 were prepared by a standard solid-state reaction. X-ray diffraction at room temperature confirms that the synthesized compound of Tb2Ti2O7 is single phase with cubic unit cell constant a0 of 1.015 44 nm. Magnetic susceptibility measurements in the temperature range between 100 and 300 K give an effective moment of 9.44 μB and Curie-Weiss temperature of 12.68 K, respectively, indicating the dominance of antiferromagnetic interactions. However, below 50 K, the magnetic behavior of Tb2Ti2O7 deviates from Curie-Weiss law, whose origin remains suspicion. 相似文献
13.
The electro-deoxidation of V2O3 precursors was studied. Experiments were carried out with a two-terminal electrochemical cell, which was comprised of a molten
electrolyte of CaCl2 and NaCl with additions of CaO, a cathode of compact V2O3, and a graphite anode under the potential of 3.0 V at 1173 K. The phase constitution and composition as well as the morphology
of the samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 3 g of V2O3 could be converted to vanadium metal powder within the processing time of 8 h. The kinetic pathway was investigated by analyzing
the product phase in samples prepared at different reduction stages. CaO added in the reduction path of V2O3 formed the intermediate product CaV2O4. 相似文献
14.
A single host white emitting phosphor, CaLaGa3O7:Dy3+, was synthesized by chemical co-precipitation. Field emission scanning electron microscopy, X-ray diffraction, laser particle size analysis, and photoluminescence and cathodoluminescence spectra were used to investigate the structural and optical properties of the phosphor. The phosphor particles were composed of microspheres with a slight tendency to agglomerate, and an average diameter was of about 1.0 μm. The Dy3+ ions acted as luminescent centers, and substituted La3+ ions in the single crystal lattice of CaLaGa3O7 where they were located in Cs sites. Under excitation with ultraviolet light and a low voltage electron beam, the CaLaGa3O7:Dy3+ phosphor exhibited the characteristic emission of Dy3+ (4F9/2-6H15/2 and 4F9/2-6H13/2 transitions) with intense yellow emission at about 573 nm. The chromaticity coordinates for the phosphor were in the white region. The relevant luminescence mechanisms of the phosphor are investigated. This phosphor may be applied in both field emission displays and white light-emitting diodes. 相似文献
15.
Porous ceramics were prepared from kaolinite gangue and Al(OH)3 with double addition of MgCO3 and CaCO3 by the pore-forming in-situ technique. The characterizations of porous ceramics were investigated by X-ray diffractometry, scanning electron microscopy,
and mercury porosimetry measurements, etc. It is found that although the decomposition of MgCO3 and CaCO3 has little contribution to the porosity, the double addition of MgCO3 and CaCO3 strongly affects the formation of liquid phase, and then changes the phase compositions, pore characterization, and strength.
The appropriate mode is the sample containing 1.17wt% MgCO3 and 1.17wt% CaCO3, which has high apparent porosity (41.0%), high crushing strength (53.5 MPa), high mullite content (76wt%), and small average
pore size (3.24 μm). 相似文献
16.
The microstructure and electrical properties of ZnO-based varistors with the SiO2 content in the range of 0–1.00mol% were prepared by a solid reaction route. The varistors were characterized by scanning
electron microscopy, X-ray diffraction, energy-dispersive X-ray spectrometry, inductively coupled plasma-atomic emission spectrometry,
and X-ray photoelectron spectroscopy. The results indicate that the average grain size of ZnO decreases with the SiO2 content increasing. A new second phase (Zn2SiO4) and a glass phase (Bi2SiO5) are found. Element Si mainly exists in the grain boundary and plays an important role in controlling the Bi2O3 vaporization. The electric measurement shows that the incorporation of SiO2 can significantly improve the nonlinear properties of ZnO-based varistors, and the nonlinear coefficients of the varistors
with SiO2 are in the range of 36.8–69.5. The varistor voltage reaches the maximum value of 463 V/mm and the leakage current reaches
the minimum value of 0.11 μA at the SiO2 content of 0.75mol%. 相似文献
17.
Zhan-lei Wu Ru Zhang Ma Zhao Shao-ming Fang Zhou-xiang Han Ji-fan Hu Kai-ying Wang 《矿物冶金与材料学报》2012,19(2):141-145
The acetone-sensing properties of the undoped and Pd doped perovskite-type oxides NdFeO3 were investigated from room temperature to 400°C. The perovskite-type NdFeO3 was synthesized by a sol-gel method, and the dopants Pd with the content from 1wt% to 5wt% were implanted into NdFeO3 nanoparticles by thermal diffusion. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques show that NdFeO3 is an orthorhombic structure with the average particle size of about 40 nm. A giant acetone-sensing response of 675.7 is
observed when the Pd content in NdFeO3 powders is about 3wt%. The response and recovery time of the sensor to the 5×10−4 acetone gas are 16 and 1 s, respectively. At the same time, it performs a good selectivity to acetone gas and may be a new
promising material candidate for the acetone-sensor development. 相似文献
18.
ShiChuang ZhuQuan-yao ShuHong JiangZhong-xing 《武汉大学学报:自然科学英文版》2004,9(1):105-108
Poly ( N, N, N-trimethyl ( 2-pyrrol-l-yl ) ethyl ammonium iodide )/V2O5 ( PTPAI/V2O5) nanocomposites were synthesized by sol-gel method. This method involved formation of vanadium pentoxide xerogel in the prcscnce of polypyrrole derivatives solution. X-ray diffraction(XRD) indicated that the polypyrrole derivative particles encapsulated in the fibrous V2O5 network and the layered distance significantly increased from 1. 077 39 to 1. 354 56 nm. The interaction between polypyrrole and V2O5 in the ‘nanocomposites‘ was characterized by IR spectroscopy. The Scanning Electron Microscope(SEM) micrographs reveal the structural contrasts between the hybrid materials and the pristine vanadium oxide xerogel. 相似文献
19.
LI Gong GAO YunPeng SUN YiNan MA MingZhen LIU Jing LIU RiPing 《科学通报(英文版)》2007,52(4):440-443
The compression behavior of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using insitu high pressure energy dispersive X-ray diffraction with a syn- chrotron radiation source. The equation of state is determined by fitting the experimental data accord- ing to Birch-Murnaghan equation: -ΔV/V0=0.08606P-3.2×10-4P2 5.7×10-6P3. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa. 相似文献
20.
We prepared highly-ordered titanium dioxide nanotube arrays (TNAs) by anodizing Ti foils in F-containing electrolytes.The crystalline nature and morphology of the TNAs were studied using X-ray diffraction patterns and scanning electron microscopy.We found the morphology of TNAs affects the light-to-electricity conversion efficiency (η) of dye-sensitized solar cells (DSSCs).The efficiency of DSSCs reached 5.95% under the condition of light illuminated from the counter electrode.The high efficiency of TNA-based DSSCs was attributed to the neat top surface of TNAs,which allows more dye molecule loading on the surface of the TiO 2 nanotubes,and fewer electron recombination centers and a low interface resistance of integrated TNAs. 相似文献