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1.
Yuanpeng Zhang Yuan Li Chunzhi Li Wenwen Wang Junying Zhang Rongming Wang 《稀有金属(英文版)》2012,31(2):168-171
The In2O3:W (IWO) films with different W content were deposited on glass substrate using direct current sputtering method. The structure, surface morphology, and optical and electrical properties were investigated. Results showed that both the carrier concentration and carrier mobility were increased with the doping of W. The IWO film with the lowest resistivity of 1. 0× 10-3 Ω· cm, highest carrier mobility of 43. 7 cm2. W-1. s-1 and carrier concentration of 1. 4× 1020 cm-3 was obtained at the content of 2. 8 wt. %. The average optical transmittance from 300 nm to 900 nm reached 87. 6%. 相似文献
2.
L. Y. Kong L. Shen B. Lu R. Yang X. Y. Cui T. F. Li T. Y. Xiong 《Journal of Thermal Spray Technology》2010,19(6):1206-1210
A novel TiAl3-Al coating was prepared by cold spray for high temperature protection of titanium aluminum-based alloy. The substrate alloy
was orthorhombic-Ti-22Al-26Nb (at.%). The composite coating was mainly composed of TiAl3 embedded in the matrix of residual aluminum. An interlayer about 10 μm was formed between the coating and the substrate.
The oxidation test indicated that this composite coating was very effective in improving the high-temperature oxidation resistance
of the substrate alloy at 950 °C in the tested 150 cycles without any sign of degradation. The microstructure analysis of
the oxidized composite coating showed that an Al2O3 scale with a complex structure can be formed outside the interlayer during oxidation and no oxides beneath the interlayer
were detected, which indicated that the complex continuous Al2O3 and the interlayer provide the protection of the substrate at high-temperature oxidation condition. 相似文献
3.
Effects of Sc doping on electrical conductivity of BaZrO<Subscript>3</Subscript> protonic conductors
BaZr1-xScxO3-0.5x (x=0.07,0.10,0.13,0.16) powders were prepared by solid-state reaction method,and ZnO was used as sintering aid.Samples with different amount of ZnO additive were sintered at 1450 ℃ for 6 h in air.Single cubic perovskite phase proton conductors were obtained.Conductivity was measured by electrochemical workstation.It was shown that Sc doping could increase conductivity through enhancing the carrier concentration in the material,but excessive Sc content might decrease the carrier concentration because of its charge compensation.ZnO had an influence on carrier concentration and mobility and affected the electrical conductivity.2 mol% ZnO and 13 mol% ScO1.5 doped sample showed the highest DC conductivity of 3.6 × 10-3 S·cm-1 tested at 800 ℃ in wet hydrogen atmosphere. 相似文献
4.
Ying Lin Baozhi Zeng Yingbin Lin Xiaowei Li Guiying Zhao Ting Zhou Heng Lai Zhigao Huang 《稀有金属(英文版)》2012,31(2):145-149
Olivine structured LiFePO4/C (lithium iron phosphate) and Mn2+-doped LiFe0. 98Mn0. 024/C powders were synthesized by the solid-state reaction. The effects of manganese partial substitution and different carbon content coating on the surface of LiFePO4 were considered. The structures and electrochemical properties of the samples were measured by X-ray diffraction (XRD), cyclic voltammetry (CV), charge/discharge tests at different current densities, and electrochemical impedance spectroscopy (EIS). The electrochemical properties of LiFePO4 cathodes with x wt. % carbon coating (x=3, 7, 11, 15) at γ=0. 2C, 2C (1C=170 mAh·g-1) between 2. 5 and 4. 3 V were investigated. The measured results mean that the LiFePO4 with 7 wt. % carbon coating shows the best rate performance. The discharge capacity of LiFe0. 98Mn0. 02PO4/C composite is found to be 165 mAh·g 1 at a discharge rate, γ=0. 2C, and 105 mAh·g-1 at γ=2C, respectively. After 10cycles, the discharge capacity has rarely fallen, while that of the pristine LiFePO4/C cathode is 150 mAh·g-1 and 98 mAh·g-1 at γ=0. 2 and 2C, respectively. Compared to the discharge capacities of both electrodes above, the evident improvement of the electrochemical performance is observed, which is ascribed to the enhancement of the electronic conductivity and diffusion kinetics by carbon coating and Mn2+-substitution. 相似文献
5.
The kinetics of forward extraction of Ti(IV) from H2SO4 medium by P507 in kerosene has been investigated using the single drop technique.In the low concentration region of Ti(IV),the rate of forward extraction at 298 K can be represented by F(kmol·m-2·s-1)=10-5.07 [TiO 2 + ][H+]-1 [NaHA 2 ](o)·Analysis of the rate expression reveals that the rate determining step is(TiO)(i)2+ +(HA 2)(i)-[TiO(HA2)](i)+.The values of Ea,H±,S±,and G±298 are calculated to be 22 kJ·mol-1,25 kJ·mol-1,-218 J·mol-1·K-1,and 25 kJ·mol-1,respectively.The experimental negative S± values indicate that the reaction step occurs via SN2 mechanism. 相似文献
6.
V. S. Rudnev T. P. Yarovaya P. M. Nedozorov A. Yu. Ustinov L. M. Tyrina I. V. Malyshev V. G. Kuryavyi V. S. Egorkin S. L. Sinebryukhov S. V. Gnedenkov 《Protection of Metals and Physical Chemistry of Surfaces》2011,47(5):621-628
Regularities of the effect produced by Ce2(SO4)3 salt introduced in an aqueous electrolyte containing Zr(SO4)2 on the plasma-electrolytic formation of oxide coatings on titanium, their composition, and structure are studied. ZrO2 + CeO
x
+ TiO2 three-phase oxide coatings with a thickness about 10 μm are obtained. The coatings involve ZrO2 cubic phase. The ZrO2-to-TiO2 phase ratio in the coatings can be controlled. The zirconium content in the coatings reaches 20 at %, while that of cerium
is 3–5 at %. The surface layer (∼3-nm thick) contains Ce3+ (∼30%) and Ce4+ (∼70%). Pores in the surface part of coatings have diameters around or smaller than 1 μm and are regularly arranged. The
obtained systems have a certain catalytic activity with respect to the oxidation of CO to CO2 at temperatures above 400–450°C. The coatings are corrosion-resistant in chloride-containing environments. The thickness
h of coatings depending on the charge Q supplied to the cell is described by the equation h = h
0(Q/Q
0)
n
, where n = 0.35 and h
0 is the thickness of the coating formed at Q
0 = 1 C/cm2. 相似文献
7.
The formation, microstructure and properties of high-density TiN/Ti5Si3 ceramic composites created by the pyrolysis of preceramic polymer with filler were investigated. Methylpolysiloxane was mixed
with TiH2 as filler and ceramic composites prepared by pyrolysis at 1200°C to 1600°C under N2, Ar and vacuum were studied. When a specimen with 70 vol.% TiH2 was pyrolyzed up to 1600°C in a vacuum after a preheat treatment at 850°C in a N2 atmosphere and subsequently heat-treated at 1600°C for 1 h under Ar at a pressure of 2 MPa, a ceramic composite with full
density was obtained. The microstructure of the ceramic composite was composed of TiN and Ti5Si3 phases. Under specific pyrolysis conditions, a ceramic composite with a density of 99.2 TD%, a Vickers hardness of 18 GPa,
a fracture toughness of 3.5 MPam1/2, a flexural strength of 270 MPa and a electrical conductivity of 6200 ohm−1·cm−1 was obtained. 相似文献
8.
Hui Li Litong Zhang Qingfeng Zeng Laifei Cheng 《Journal of Phase Equilibria and Diffusion》2011,32(5):422-427
The thermodynamics of the oxidation of HfB2 at temperatures of 1000, 1500, 2000, and 2500 K have been studied using volatility diagrams. Both the equilibrium oxygen
partial pressure (
P\textO2 P_{{{\text{O}}_{2} }} ) for the HfB2(s) to HfO2(s) plus B2O3(l) and the partial pressures of B-O vapor species formed due to B2O3(l) volatilization increase with increasing temperature. Vapor pressures of the predominant gaseous species also increase
with
P\textO2 P_{{{\text{O}}_{2} }} . At 1000 K, the predominant vapor transition sequence is predicted be BO(g) → B2O2(g) → B2O3(g) → BO2(g) with increasing
P\textO2 P_{{{\text{O}}_{2} }} , and the predominant gas is BO2(g) with a pressure of 1.27 × 10−6 Pa under the condition of
P\textO2 P_{{{\text{O}}_{2} }} = 20 kPa. At higher temperatures of 1500, 2000, and 2500 K, the system undergoes vapor transitions in the same sequence of
B(g) → BO(g) → B2O2(g) → B2O3(g) → BO2(g). Under the same condition of
P\textO2 P_{{{\text{O}}_{2} }} = 20 kPa, the predominant vapor species is B2O3(g) with pressures of 2.38, 4.49 × 103, and 3.55 × 105 Pa, respectively. Volatilization of B2O3(l) may produce porous HfO2 scale, which is consistent with the experimental observations of HfB2 oxidation in air. The present volatility diagram of HfB2 shows that HfB2 exhibits oxidation behavior similar to ZrB2, and factors other than volatility of gaseous species affect the oxidation rate. 相似文献
9.
Joon Woo Bae Jae-Won Lim Sun Joong Kim Kouji Mimura Takamichi Miyazaki Masahito Uchikoshi Minoru Isshiki 《Metals and Materials International》2010,16(3):447-452
ZrO2 dielectric layers were prepared by a two-step process, a deposition of pure Zr film with and without a negative substrate
bias voltage and a subsequent oxidation of the Zr films. We focused on the effect of the negative substrate bias voltage on
the Zr film deposition and the subsequent oxidation of the Zr films. As a result, the Zr film deposited at the substrate bias
voltage of −50 V (Vs = −50 V) was found to have a high intensity peak of Zr (100) and a uniform and smooth surface. From the
capacitance-voltage and current-voltage measurements of the ZrO2 films, a high dielectric constant of 21 and the equivalent oxide thickness (EOT) of 2.6 nm were obtained on the oxidation
layer of the Zr film deposited at Vs = −50 V. On the other hand, a low dielectric constant of 15 and the EOT of 3.6 nm was
obtained on that of the Zr film deposited at Vs = 0 V. The leakage current density of the ZrO2 film (Vs = −50 V) was 5.69×10−4 A/cm2, and this value was much lower than the 1.21×10−4 A/cm2 for the ZrO2 film (Vs = 0 V). It was found that the two-step process by subsequent oxidation after film deposition using a negative substrate
bias voltage is useful for obtaining high-quality dielectric layers. 相似文献
10.
A new technology was developed to recover V2O5 from Bayer spent liquor by ion exchange.The experimental results show that in the conditions of 105°C and 0.20-0.25 mass ratios between CaO in lime and Al2O3 in spent liquor, the precipitation rate of vanadium in Bayer liquor is more than 85%.The vanadium-bearing precipitation is leached by NaHCO3 solution.The leaching rate of vanadium can reach 85% in the conditions of 95°C, 40 g·L-1 of NaHCO3 concentration, and ventilating of CO2.The 201 × 7 type of resin has... 相似文献
11.
Ki-Ju Lee Jing-Wen Xu Cheol-Ho Lim Won-Seung Cho 《Metals and Materials International》2008,14(4):433-436
In this study, the thermoelectric properties of 0.1 wt.% Cdl2-doped n-type Bi2Te2.7Sb0.3 compounds, fabrieated by SPS in a temperature range of 250°C to 350°C, were characterized. The density of the compounds was
increased to approximately 100% of the theoretical density by carrying out consolidation at 350°C. The Seebeck coefficient,
thermal conductivity, and electrical resistivity were dependent on a hydrogen reduction process and the sintering temperature.
The Seebeck coefficient and the electrical resistivity increased with the reduction process. Also, electrical resistivity
decreased and thermal conductivity increased with sintering temperature. The results suggest that carrier density and mobility
vary according to the reduction process and sintering temperature. The highest figure of merit, 1.93×10−3 K−1, was obtained for the compound consolidated at 350°C for 2 min. 相似文献
12.
N. Garimella M. Ode M. Ikeda H. Murakami Y. H. Sohn 《Journal of Phase Equilibria and Diffusion》2009,30(3):246-253
Ternary interdiffusion in L12-Ni3Al with ternary alloying addition of Re was investigated at 1473 K using solid-to-solid diffusion couples. Interdiffusion
flux of Ni, Al, and Re were directly calculated from experimental concentration profiles and integrated for the determination
of average ternary interdiffusion coefficients. The magnitude of main interdiffusion coefficients and was determined to be much larger than that of the main interdiffusion coefficient A moderate tendency for Re to substitute for Al sites was reflected by its influence on interdiffusion of Al, quantified
by large and positive coefficients. Similar trends were observed from ternary interdiffusion coefficients determined by Boltzmann-Matano analysis.
Profiles of concentrations and interdiffusion fluxes were also examined to estimate binary interdiffusion coefficients in
Ni3Al, and tracer diffusion coefficients of Re (5.4 × 10−16 ± 2.3 × 10−16 m2/s) in Ni3Al. 相似文献
13.
La0.75Sr0.25Cr
y
Mn1−y
O3 (LSCM) (y = 0.0–0.6) composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid (EDTA)
and citrate. X-ray diffraction (XRD), temperature-programmed reduction, electrical conductivity, I–V polarization, and impedance spectroscopy were conducted to investigate the Cr doping effect of La0.75Sr0.25MnO3 on its phase stability and electrochemical performance as a solid-oxide fuel cell (SOFC) anode. The chemical and structural
stabilities of the oxides increased steadily with increasing Cr doping concentration, while the electrical conductivity decreased
on the contrary. At y ≥ 0.4, the basic perovskite structure under the anode operating condition was sustained. a cell with 0.5-mm-thick scandia-stabilized
zirconia electrolyte and La0.75Sr0.25Cr
y
Mn1−y
O3 anode delivered a power density of ∼15 mW·cm−2 at 850°C. 相似文献
14.
Nanostructured skutterudite-related compound Fe0.25Ni0.25Co0.5Sb3 was synthesized by a solvothermal method using FeCl3, NiCl2, CoCl2, and SbCl3 as the precursors and NaBH4 as the reductant. The solvothermally synthesized powders consisted of fine granules with an average particle size of tens
of nanometers. The bulk material was prepared by hot pressing the powders. Transport property measurements indicated a heavily
doped semiconductor behavior with n-type conduction. The thermal conductivity is about 1.83 W·m−1·K−1 at room temperature and decreases to 1.57 W·m−1·K−1 at 673 K. The low thermal conductivity is attributed to small grain size and high porosity. A maximum dimensionless figure
of merit of 0.15 is obtained at 673 K. 相似文献
15.
In Sung Kim Soon Jong Jeong Jae Sung Song Pan Seok Shin 《Metals and Materials International》2002,8(6):577-582
The present study describes the dielectric properties of RF sputtered Ta2O5 thin films as a function of the buffer layer and annealing condition. The buffer layers were Ti or TiO2. And the thin film was annealed in various conditions. The X-ray pattern results showed that the phase of the RF sputtered
Ta2O5 thin films was amorphous and this state was kept stable to RTA (rapid thermal annealing) even at 700°C. Measurements of the
electrical and dielectric properties of the reactive sputtered Ta2O5 fabricated in two simple metal insulator semiconductor (MIS) structures, (Cu/Ta2O5/Ti/Si/Cu and Cu/Ta2O5/TiO2/Si/Cu) indicated that the amorphous Ta2O5 grown on Ti possesses a high dielectric constant (30–70) and high leakage current (10−1–10−4 A/cm2), whereas a relatively low dielectric constant (−10) and low leakage current (−10−10 A/cm2) were observed in the amorphous Ta2O5 deposited on the TiO2 buffer layer. In addition, the leakage current mechanisms of the two amorphous Ta2O5 thin films were investigated by plotting the relation of current density (J) vs. applied electric field (E). The Ta2O5/Ti film exhibited three dominant conduction mechanism regimes contributed by the Ohmic emission at low electrical field,
by the Schottky emission at intermediate field and by the Poole-Frenkel emission at high field. In the case of Ta2O5/TiO2 film, the two conduction mechanisms, the Ohmic and Schottky emissions, governed the leakage current density behavior. The
conduction mechanisms at various electric fields applied were related to the diffusion of Ta, Ti and O, followed by the creation
of vacancies, in the rapid thermal treated capacitors. 相似文献
16.
The electrochemical properties of spinel compound LiNi0.5Mn1.2Ti0.3O4 were investigated in this study.The chemicals LiAc·2H2O,Mn(Ac)2·2H2O,Ni(Ac)2·4H2O,and Ti(OCH3)4 were used to synthesize LiNi0.5Mn1.2Ti0.3O4 by a simple sol-gel method.The discharge capacity of the sample reached 134 mAh/g at a current rate of 0.1C.The first and fifth cycle voltammogram almost overlapped,which showed that the prepared sample LiNi0.5Mn1.2Ti0.3O4 had excellent good cycle performance.There were two oxidation peaks at 4.21 V and 4.86 V,and two reduction peaks at 4.55 V and 3.88 V in the cycle voltammogram,respectively.By electrochemical impedance spectroscopy and its fitted result,the lithium ion diffusion coefficient was measured to be approximately 7.76 × 10?11 cm2/s. 相似文献
17.
Deuk Yong Lee Myung-Hyun Lee Nam-Ihn Cho Bae-Yeon Kim Young-Jei Oh 《Metals and Materials International》2010,16(3):453-457
Barium titanate (BaTiO3, BT) nanofibers with a diameter range of 160 nm to 300 nm were prepared by drying electrospun BT/polyvinylpyrrolidone (BT/PVP)
composite fibers for 1 h at 80 °C in vacuum with a subsequent calcination in air for 1 h at a temperature range of 650 °C
to 750 °C. The morphology and crystal structure of calcined BT nanofibers were characterized with the aid of XRD, FT-IR, SEM,
and TEM. The XRD and FR-IR measurements confirm that BT nanofibers with a diameter of about 160 nm and a tetragonal perovskite
structure were present in the electrospun fibers after calcination for 1 h at 750 °C. The FR-IR analysis of the BT fibers
reveals that the intensity level of the O-H stretching vibration bands (at 3430 cm−1 and 1425 cm−1) become weaker as the calcination temperature is increased and that a broad band at 570 cm−1, which represents the Ti-O vibration, appears sharper and narrower after calcination at 750 °C due to the formation of metal
oxide bonds. In contrast, BT fibers prepared by a refluxing process in a nitrogen atmosphere show a dramatic change in crystal
structure: the tetragonal structure changes to a cubic perovskite structure, probably due to the suppression of carbonate
contamination. Thus, the calcination temperature and atmosphere appear to have a significant influence on the crystal structure
of BT. 相似文献
18.
Fabrication and characterization of SmO_(0.7)F_(0.2)FeAs bulk with a transition temperature of 56.5 K 总被引:1,自引:1,他引:0
The superconductivity of iron-based superconductor SmO 0.7 F 0.2 FeAs was investigated. The SmO 0.7 F 0.2 FeAs sample was prepared by the two-step solid-state reaction method. The onset resistivity transition temperature is as high as 56.5 K. X-ray diffraction (XRD) results show that the lattice parameters a and c are 0.39261 and 0.84751 nm, respectively. Furthermore, the global J c was more than 2.3 × 10 5 A/cm 2 at T = 10 K and H = 9 T, which was calculated by the formula of J c = 20ΔM/[a(1-a/(3b))]. The upper critical fields, H c2 ≈ 256 T (T = 0 K), was determined according to the Werthamer-Helfand-Hohenberg formula, indicating that the SmO 0.7 F 0.2 FeAs was a superconductor with a very promising application. 相似文献
19.
O. V. Lozovaya M. R. Tarasevich V. A. Bogdanovskaya I. V. Kasatkina A. I. Shcherbakov 《Protection of Metals and Physical Chemistry of Surfaces》2011,47(1):48-53
TiO2 nanotubes (TiO2 NTs) were synthesized using the electrochemical method in a 1 M H2SO4 + 0.15% HF electrolyte. The initial nanotubes have a diameter of 100 ± 10 nm (with the length of up to 150–200 nm) and a
wall thickness of 20 ± 5 nm. Nanotube treatment at 400°C results in negligible changes in their structure compared to the
initial samples. At 600°C, a change occurs in the nanotube structure and morphology, i.e., the amount decreases drastically;
the diameter changes; and, as a consequence, the surface area value decreases. Changes in the structure lead to changes in
the electrochemical properties, which is apparently related to a transition from the amorphous structure to anatase and rutile.
It is shown that a reversible two-electron reaction, including hydrogen intercalation and Ti4+/Ti3+ oxidation/reduction in the potential range of (−0.6−0.4 V), occurs as a result of moderate thermal treatment. The possibility
of the use and promising character of TiO2 NTs as support for a nonplatinum catalyst based on cobalt tetra(p-methoxyphenyl)porphyrin are brought to light. The electrocatalytic activity of the synthesized catalyst per nominal CoTMPP
mass in the reaction of O2 reduction at E = 0.7 V is ≈25 A/gCoTMPP, which is comparable to nonplatinum systems on a carbon support. 相似文献
20.
Grażyna Dąbrowska Piotr Tabero Maria Kurzawa 《Journal of Phase Equilibria and Diffusion》2009,30(3):220-229
Phase relations in the ternary oxide system Al2O3-V2O5-MoO3 in the solid state in air have been investigated by using the x-ray diffraction (XRD) and differential thermal analysis/thermogravimetric
(DTA/TG) methods. It was confirmed that in the subsolidus area of the Al2O3-V2O5-MoO3 system, there exist seven phases, that is Al2O3, V2O5(s.s.), MoO3, AlVO4, Al2(MoO4)3, AlVMoO7, and V9Mo6O40. Seven fields, in which particular phases coexist at equilibrium, were isolated. The crystal structure of AlVO4 has been refined from x-ray powder diffraction data. Its space group is triclinic, , Z = 6, with a = 0.65323(1) nm, b = 0.77498(2) nm, c = 0.91233(3) nm, α = 96.175(2)°, β = 107.234(3)°, γ = 101.404(3)°, V = 0.42555 nm3. The crystal structure of the compound is isotypic with FeVO4. Infrared (IR) spectra of AlVO4 and FeVO4 are compared. 相似文献