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1.
闵新民 《武汉理工大学学报(材料科学英文版)》2007,22(1):27-30
The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SiAl1-xC has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al 3/7. 相似文献
2.
钟胜奎 《武汉理工大学学报(材料科学英文版)》2009,24(3):343-346
Cr-doped Li3V2(PO4)3 cathode materials Li3V2−x
Cr
x
(PO4)3 were prepared by a carbothermal reduction(CTR) process. The properties of the Cr-doped Li3V2(PO4)3 were investigated by X-ray diffraction (XRD), scanning electron microscopic (SEM), and electrochemical measurements. Results
show that the Cr-doped Li3V2(PO4)3 has the same monoclinic structure as the undoped Li3V2(PO4)3, and the particle size of Cr-doped Li3V2(PO4)3 is smaller than that of the undoped Li3V2(PO4)3 and the smallest particle size is only about 1 μm. The Cr-doped Li3V2(PO4)3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV),
and electrochemical impedance spectra(EIS). The optimal doping content of Cr was that x=0.04 in the Li3V2−x
Cr
x
(PO4)3 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced,
and the charge transfer resistance was decreased through the Cr-doping. The improved electrochemical performances of the Cr-doped
Li3V2(PO4)3 cathode materials are attributed to the addition of Cr3+ ion by stabilizing the monoclinic structure.
Funded by the Guangxi Natural Science Foundation(No. 0832259) and the National Basic Research Program of China (No. 2007CB613607) 相似文献
3.
Guo DongYun Li MeiYa Liu Jun Yu BenFang Pei Ling Wang YunBo Yu Jun Yang Bin 《中国科学E辑(英文版)》2008,51(1):10-15
We have investigated the preparation and properties of Bi3.4Ce0.6Ti3O12 thin films. The Bi3.4Ce0.6Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction
and atomic force microscopy. The thin films showed a perovskite phase and dense microstructure. The dielectric constant and
the dissipation factor of the Bi3.4Ce0.6Ti3O12 thin films were about 172 and 0.031 at 1 kHz, respectively. The 2P
r and 2E
c of the Bi3.4Ce0.6Ti3O12 thin films were 67.1 μC/cm2 and 299.7 kV/cm, respectively, under an applied field of 600 kV/cm. The Bi3.4Ce0.6Ti3O12 film did not show fatigue up to 4.46×109 switching cycles at a frequency of 1 MHz, and showed good insulating behavior according to the test of leakage current.
Supported by the Natural Science Foundation of Hubei Province (Grants No. 2004ABA082) 相似文献
4.
《中国科学E辑(英文版)》2009,(1)
In this paper, the effects of Si and Ce on the microstructure and hydrogen storage property of Ti26.5 Cr20V45Fe8.5Ce0.5 alloy were studied, respectively. First of all, effects of Si on the microstructure and hydrogen storage properties of Ti26.5Cr20(V45Fe8.5)1?xSixCe0.5 (x = 0, 0.5, 1.0, 1.5 and 2.0 at%) alloys were studied by X-ray diffraction, scanning electron microscopy and P-C isotherm measurements. As the Si addition increases, the hydrogen absorption capacities of alloys decrease but the equilibrium pressure increases, due to the formation of Laves phase. Secondly, the effect of Ce on Ti26.5Cr20 (V45Fe8.5)0.98Si2 alloy was studied. It was found that Ce addition is an effective way to eliminate the effect of Si on the hydrogen storage properties of the alloy. 相似文献
5.
陈力颖 《武汉理工大学学报(材料科学英文版)》2008,23(5):647-651
The microwave dielectric properties and microstructure of BaTi4.3ZnyO9.6+y +0.02 mol% SnO2+0.01 mol% MnCO3+x mol% Nb2O5(x=0-0.05, y=0-0.08) system ceramics were studied as a function of the amount of ZnO and Nb2O5 doped. Addition of (y=0-0.05) ZnO and (x=0-0.025) Nb2O5 enhanced the reactivity and decreased the sintering temperature effectively. It also increased the dielectric constant ε r and quality factor Q(=1/tan 8) of the system due to the substitution of Ti^4+ ions with incorporating Zn^2+and Nb^5+ ions, which was analyzed by the reaction ZnO+Nb2O5+ 3 TiTxTi →ZnTi+ 2NbTi+3TiO2. When the system doped with (y=0.05) ZnO and (x=0.025) Nb205 were sintered at 1 160 ℃ for 6 h, the εr. Qf0 value and rfwere 36.5, 42 000 GHz, and+1.8 ppm/℃, respectively, at 5 GHz. 相似文献
6.
Poly ethylene oxide (PEO)x−V2O5−V2O5−MoO3 (x=0, 0.5, 1) films were prepared by the sol-gel method. The synthesis and structure of the films were investigated by XRD,
TG-DTA, FTIR, etc. The results show that V2O5−MoO3 xerogel has a layered structure and its interlayer space increased from 1.3181 nm at x=0 to 1. 7898 nm at x=1 after the nanocomposite
films were dried, and PEO in the interlayer changes the interface structure by forming hydrogen bonds with V=0 bands. CV measurement
indicates that the intercalation of PEO improves insertion/extration properties of Li+ ions in the interlayer.
ZHENG Jin-xia: Born in 1976
Funded by the National Natural Science Foundation of China (No. 50172036) and Natural Science Foundation of Hubei Province(No.
2001ABB083) 相似文献
7.
KoKai Tseng YaChu Yang ChienChang Juan TsungShune Chin CheWei Tsai JienWei Yeh 《中国科学:技术科学(英文版)》2018,61(2):184-188
A light-weight high-entropy alloy (LWHEA) Al20Be20Fe10Si15Ti35 has been developed to have unique mechanical properties and oxidation resistance. One major and two minor phases are observed in the as-cast microstructure. The density of the alloy is 3.91 g cm?3, and its hardness is HV 911, which is higher than quartz. The hardness and hardness to density ratio are the highest of all light-weight alloys reported before. In addition, it has excellent oxidation resistance at 700°C and 900°C, which far exceeds that of Ti-6Al-4V. Thus, the combination of properties is promising for high-temperature applications, which require light weight, wear-resistant and oxidation-resistant components. 相似文献
8.
赵青南 《武汉理工大学学报(材料科学英文版)》2008,23(4):443-447
CeO2-TiO2 films and CeO2-TiO/SnO2:Sb (6 mol%) double films were deposited on glass substrates by radio-frequency magnetron sputtering (R.F. Sputtering), using SnO2:Sb(6 mol%) target, and CeO2- TiO2 targets with different molar ratio of CeO2 to TiO2 (CeO2:TiO2-0:1.0; 0.1:0.9; 0.2:0.8; 0.3:0.7; 0.4:0.6; 0.5:0.5; 0.6:0.4; 0.7:0.3; 0.8:0.2; 0.9:0.1; 1.0:0). The films are characterized by UV-visible transmission and infrared reflection spectra, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The obtained results show that the amorphous phases composed of CeO2-TiO2 play an important role in absorbing UV, there are Ce^3-, Ce^4- and Ti^4- on the surface of the films; the glass substrates coated with CeO2-TiO2 (Ce/Ti=0.5:0.5; 0.6:0.4)/SnO2:Sb(6 mol%) double films show high absorbing UV(〉99), high visible light transmission (75%) and good infrared reflection (〉70%). The sheet resistance of the films is 30-50 Ω/□. The glass substrates coated with the double functional films can be used as window glass of buildings, automobile and so on. 相似文献
9.
ZHUJiao-qun MEIBing-chu CHENYan-lin 《武汉理工大学学报(材料科学英文版)》2003,18(1):37-40
Polycrystalline bulk Ti3SiC2 material with a high purity and density was fabricated by spark plasma sintering from the elemental powder mixture with starting composition of Ti3Si3Si1-xAlxC2 , where x = 0. 05 -0.2. X-ray diffraction patterns and scanning electron microscopy photographs of the fully dense samples show that a proper addition of aluminum promotes the formation, and accelerates the crystal growth rate of Ti3SIC2, conse-quently results in a high purity of the prepared samples. The synthesized Ti3 SiC2 is in plane-shape with a size of about 10- 25μm in the elongated dimension. Solid solution of aluminum decreases the thermal stability of Ti3SiC2, and lowers the temperature of Ti3SiC2 decomposeing to be 1300 ℃ . 相似文献
10.
陆洪智 《武汉理工大学学报(材料科学英文版)》2011,26(4):668-670
Influences of addition of CaO, CoO and V2O5 on the microstructure and magnetic properties of (Mg0.476Mn0.448Zn0.007)(Fe1.997Ti0.002)O4 ferrites were investigated. The powders of (Mg0.476Mn0.448Zn0.007) (Fe1.997Ti0.002)O4 composition were prepared by using a conventional ceramic powder processing technique. The experimental results showed that the average grain size of the sintered ferrites codoped with 0.03wt% CaO, 0.04wt% CoO and 0.06wt% V2O5 was about 15 μm; the saturation magnetization of ferrites was 68.78 emu/g. The addition of V2O5 in the ferrites can not only increase value of the saturation magnetization, but also decrease the average grain size of (Mg0.476Mn0.448Zn0.007)(Fe1.997Ti0.002)O4 ferrites. Simultaneous incorporation of CoO, CaO and V2O5 dopants into (Mg0.476Mn0.448Zn0.007)(Fe1.997Ti0.002)O4 ferrites can not only improve the saturation magnetization of the materials, but also inhibit abnormal grain growth. 相似文献
11.
A metallic crystalline/amorphous (c/a) bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscope (SEM), the composite consists of the primary dendrite α-Ee (without Si) as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays (EDAX), SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy. 相似文献
12.
Effects of Zr addition and annealing treatment on the formation, microstructure and magnetic properties of Nd12.3Fe81.7−x
Zr
x
B6.0 (x=0−3.0) ribbons melt-spun and annealed have been systematically investigated by means of vibrating sample magnetometer (VSM),
differential scanning calorimeter (DSC), X-ray diffraction (XRD), and high resolution scanning electron microscopy (HRSEM).
Phase analysis reveals that Nd2Fe14B is single-phase material. It has been found that the intrinsic coercivity H
ci of the optimally processed Nd12.3Fe81.7−x
Zr
x
B6.0 ribbons increases monotonically from 751.7 kA/m for x=0 to 1005.3 kA/m for x=3.0. The remanence polarization J
r and maximum energy product (BH)max increase first with Zr addition, then slightly decrease with further increasing Zr content. Optimum magnetic properties with
J
r=1.041 T, H
ci=887.5 kA/m and (BH)max=175.2 kJ/m3 have been achieved for the ribbons with x=1.5. The significant improvement of magnetic properties originates from the finer grains of the ribbons by introducing Zr. 相似文献
13.
(Ni0.81 Fe0.19)0.66 Cr0.34 has a high resistivity and a crystal structure close to that of Ni0.81 Fe0.19. The electrical and X-ray diffraction measurements prove that a thin NiFeCr seed layer induces a well (111)-orented Ni0.81 Fe0.19 film. Post-annealing treatment improves the magnetic properties of (Ni0.81Fe0.19)0.66 Cr0.34(45Å)/Ni0.81Fe0.19 (150Å)/Ta(55Å) thin film prepared under a deposition field, whereas the inter-diffusion of NiFe/Ta deteriorates the magnetoresistance properties of the film. 相似文献
14.
Zhaofeng Li 《武汉理工大学学报(材料科学英文版)》2008,23(6):859-862
The phase structure and electrical properties of pure and La2O3-doped Bi-InO3-PbTiO3 (BI-PT) ceramics were studied respectively. In (1 -x)BI-xPT (x=0.72-0.80) ceramics, the stability of tetragonal phase increased with increasing x, and pure perovskite structure was obtained for x=-0.80 ceramics. The phase transition temperature range was between 575 ℃ and 600 ℃ for x=0.72-0.80 ceramics, higher than that of PT (-490 ℃). The c/a ratio almost linearly decreased with increasing La2O3 content in x-0.80 ceramics. It is believed that Pb^2+ vacancies were formed by La^3+ substituting Pb^2+ in La2O3-doped BI-PT ceramics. Tc shifted to lower temperature by 30 ℃/mol% La2O3. The maximum dielectric constant 8557 around 559 ℃ was exhibited in 0.5mol%-doped BI-0.80PT ceramics. La2O3-doped ceramics could be poled resulting from decreasing of c/a ratio and improving of dielectric loss and resistivity. The maximum piezoelectric coefficient d33 was 12 pC/N for 2mol%-doped BI-0.80PT ceramics. 相似文献
15.
Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power mixtures.Volume fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions process.TiC and Ti5Si3 were two important intermediate phases during the whole reactions.The microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix. 相似文献
16.
The principal refractive indices and the thermal refractive index coefficients for Be3Al2Si6O18 crystal doped with 1.01wt% Cr2O3 have been accurately measured by the auto-collimation method at wavelengths of 0.488, 0.53975, 1.064, 1.0795 and 1.3414 μm,
and temperatures of 308.2, 328.6, 359.1 and 395.4 K respectively. Based on the measured results of principal indices of 0.488,
0.6328, 1.0795 and 1.3414μm, the Sellmeier’s equations and the thermal refractive index coefficients have been obtained, and
the result has been proven to be accurate by error analysis. 相似文献
17.
(PEO)
x
−(V0.85Mo0.15)2O5(x=0,0.5,1.0) nanocomposite films were prepared by a modified sol-gel method. The structure of the films was analyzed by XRD,
and the DC electrical conductivity. Cyclic voltammogram and optical spectral transmittance were investigated. The results
show that the (V0.85Mo0.15)2O5 xerogel has a layered structure and its interlayer space increased from 1.3181 nm at x=0 to 1.7897 nm at x=1.0. The introduction
of MoO3 improved the DC electrical conductivities of the films due to the generation of V4+ to maintain the electrical neutrality of the oxides. PEO intercalated in the interlayer of (V0.85Mo0.15)2O5 oxides has interaction with the oxides, enhancing the amount of Li+ ions inserted into the interlayer of the oxides. Moreover, the intercalation of PEO into the interlayer of (V0.85Mo0.15)2O5 oxides improved the cathodic electrochromic property in near ultraviolet region and anodic electrochromic property in visible
range.
JIANG Cong-sheng: Born in 1963
Supported by the Science Foundation of Hubei Province (Grant No. 2001ABB083) 相似文献
18.
Qiang Li 《中国科学E辑(英文版)》2009,52(7):1919-1922
Nanostructured Fe40Ni40P14B6 alloy ingots of 3–5 mm in diameter could be synthesized by a metastable liquid state spinodal decomposition method. For undercooling
ΔT > 260 K, the microstructure of the undercooled specimen had exhibited liquid state spinodal decomposition in the undercooled
liquid state. The microstructure could be described as two intertwining networks with small grains dispersed in them. For
undercooling ΔT > 290 K, the overall microstructure of the specimen changed into a granular morphology. The average grain sizes of the small
and large grains are ≅ 30 nm and ≅ 80 nm, respectively. These prepared samples are soft magnets with saturation magnetization
B
s
≅ 0.744 T.
Supported by the Hong Kong Research Grants Council the National Natural Science Foundation of China (Grant No. 50861007) and
Xinjiang University Doctoral Research Start-up Grant (Grant No. BS050102) 相似文献
19.
Guo DongYun Li MeiYa Liu Jun Pei Ling Yu BenFang Zhao XingZhong Yang Bin Wang YunBo Yu Jun 《中国科学E辑(英文版)》2007,50(4):472-477
The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant (ε) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect because of the BZT film's ferroelectric polarization. 相似文献
20.
付承菊 《武汉理工大学学报(材料科学英文版)》2008,23(5):622-624
The Bi4Ti3Oi2 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr (remanent polarization) value of Bi3.25La0.75Ti3O12 thin films is 18.6 μC/cm^2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.2eLa0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed. 相似文献