共查询到20条相似文献,搜索用时 31 毫秒
1.
林英光 《武汉理工大学学报(材料科学英文版)》2011,26(5):852-856
The ZrO2/TiO2 pillared laponite (Ti-Zr-lap) photocatalysts were prepared with intercalation reaction by supercritical fluid drying (SCFD),and characterized by XRD,TEM,SEM and BET surface area analysis,and the photocatalytic properties of Ti-Zr-lap were investigated by degradation of azo dye acid red B (ARB).The results showed that the ZrO2/TiO2 pillared structures in laponite could be formed,with the mass fraction of (Zr4++Ti4+)/laponite (Xm) increasing,the basal spacing and the BET surface area of Ti-Zr-lap significantly increased.The Ti-Zr-lap used as photocatalyst had the advantages of stable and porous layered structure,large surface area with the anatase type TiO2.Compared with the Ti-Zr-lap dried by air drying,the Ti-Zr-lap dried by SCFD showed better photocatalytic property which was very close to that of P25 TiO2.Using the Ti-Zr-lap as photocatalyst with the optimum Xm of 0.16 and the calcination temperature of 500 ℃,under the conditions of the initial concentration of ARB 20 mg/L,photocatalyst concentration of 1.5 g/L and irradiation time 60 min,the decoloring rate of ARB could achieve 98.3%,indicating that the Ti-Zr-lap had excellent photocatalytic property. 相似文献
2.
徐晓虹 《武汉理工大学学报(材料科学英文版)》2010,25(3):370-374
A series of nanometer TiO2 photocatalysts co-doped respectively with rare earth Er3+-Ce3+ and La3+-Fe3+ were prepared by sol-gel method,and the photocatalytic activity under ultra-violet light was evaluated by photocatalytic degradation of methyl blue.The crystallographic forms,particles size,and morphology were characterized by XRD and TEM.The results showed that the optimum heat temperature of co-doped TiO2 was 550 ℃,and the co-doped TiO2 kept anatase.The anatase crystal had the average size of 20 nm.The ... 相似文献
3.
杨志远 《武汉理工大学学报(材料科学英文版)》2007,22(3):457-461
Nitrogen-doped TiO2 nanocrystalline powders were prepared by hydrolysis of tetrachloride titanium (TiCl4) in a mixed solution of ethanol and ammonium nitrate (NH4NO3) at ambient temperature and atmosphere followed by calcination at 400 ℃ for 2 h in air. FTIR spectra demonstrate that amine group in original gel is eliminated by calcination, and the TiO2 powder is liable to absorb water onto its surface and into its capillary pore. XRD and SEM results show that the average size of nanocrystalline TiO2 particles is no more than 60 nm and with increasing the calcination temperature, the size of particles increases. XPS studies indicate the nitrogen atom enters into the TiO2 lattice and occupies the position of oxygen atom. The nitrogen doping not only depresses the grain growth of TiO2 particles, but also reduces the phase transformation temperature of anatase to futile. The photocatalytic activity of the nitrogen-doped TiO2 powders has been evaluated by experiments of photocatalytic degradation aqueous methylene blue. 相似文献
4.
王觅堂 《武汉理工大学学报(材料科学英文版)》2016,31(4):830-834
ZnO-B2O3-SiO2-Al2O3-Na2O glass doped with nucleating agent TiO2 was prepared with melting-quenching method and the effect of nucleating agent on the crystallization behavior and phase evolution of this glass was investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The experimental results show that the glass transition temperature and the first crystallization temperature decrease from 630 °C and 765 °C to 595 °C and 740 °C, respectively, with introduction of TiO2 into glass. There is no diffraction peaks in the XRD pattern but it is no longer transparent for the base glass without nucleating agent after heat treatment, which suggests the serious phase separation occurred, and the observation by SEM indicates that the phase separation is developed by nucleation and growth mechanism. However, there are two different crystals ZnAl2O4 and NaAlSiO4 present in the glass containing TiO2 after heat treating at 575 °C for 2 h and 740 °C for 6 h, respectively. What is interesting is that NaAlSiO4 disappears as the crystallization time at 740 °C increases from 6 h to 12 h, and more ZnAl2O4 crystal is formed, namely, the further formation of ZnAl2O4 is at cost of NaAlSiO4 with increasing crystallization time. And observation of the morphology of glass ceramics shows great difference with increasing crystallization time. Moreover, the ability of ZnO-B2O3-SiO2-Al2O3-Na2O glass ceramics against attacking of 1M HCl solution is increased by the crystals precipitated in heat treatment process. 相似文献
5.
The Sm3+-doped SrO-Al2O3-SiO2 (SAS) glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-ceramics were investigated by DTA, XRD, SEM and luminescence spectroscopy. The results indicate that the crystal phase precipitated in this system is monocelsian (SrAl2Si2O8) and with the increase of nucleation/crystallization temperature, the crystallite increases from 66 % to 79 %. The Sm3+-doped SAS glass-ceramics emit green, orange and red lights centered at 565, 605, 650 and 715 nm under the excitation of 475 nm blue light which can be assigned to the 4G5/2→6 H j/2 (j=5, 7, 9, 11) transitions of Sm3+, respectively. Besides, by increasing the crystallization temperature or the concentration of Sm3+, the emission lights of the samples located at 565, 605 and 650 nm are intensified significantly. The present results demonstrate that the Sm3+-doped SAS glass-ceramics are promising luminescence materials for white LED devices by fine controlling and combining of these three green, orange and red lights in appropriate proportion. 相似文献
6.
Ferroelectric Ba0.7Sr0.3TiO3(BST) and partially Pb^2+ substituted for Ba^2+ ceramics (Ba0.7-xPbx)Sr0.3TiO3 (x=0.1-0.4, BPST) were prepared by using conventional solid-reaction method. XRD analysis shows that the samples microstructure changes from cubic phase to tetragonal one with the Pb^2+ content increasing. ESEM analysis shows that the Pb^2+ substituted samples have a denser and more uniform surface morphology than that of pure BST. Measured electrical properties suggest that the Pb^2+ substitution for Ba^2+ in the BST system enhances the ferroelectric performance obviously when x=0.2. In addition, the substitution increases the samples Curie temperature (To) r (Ba0.5Pb0.2)Sr0.3TiO3 ceramic has good ferroelectric properties measured at a maximal electric field of 30 kV/cm under the condition of room temperature. The corresponding saturated polarization (Ps), remnant polarization (Pr) and coercive field (Ec) is respectively 15.687 μC/cm^2, 8.100 μ C/cm^2 and 6.611 kV/cm. The measured Tc of (Ba0.5Pb0.2)Sr0.3TiO3 is 117 ℃. 相似文献
7.
In this paper, uniform titania (TiO2) films have been formed at 50° on silanol SAMs by the liquid-phase deposition (LPD) method at a temperature below 100°C.
OTS (Octadecyltrichloro-Silane) self-assembled monolayers (SAMs) on glass wafers were used as substrates for the deposition
of titanium dioxide thin films. This functionalized organic surface has shown to be effective for promoting the growth of
films from titanic aqueous solutions by the LPD method at a low temperature below 100°C. The crystal phase composition, microstructure
and topography of the as-prepared films were characterized by various techniques, including X-ray diffraction (XRD), scanning
electron microscopy (SEM), and atomic force microscopy (AFM). The results indicate that the as-prepared thin films are purely
crystallized anatase TiO2 constituted by nanorods after being annealed at 500°. The pH values, concentration of reactants, and deposition temperatures
play important roles in the growth of TiO2 thin films.
Support by the National Natural Science Foundation of China (Grant No. 50672055) and National Key Technology R&D Program (Grant
No. 2006BAF02A28) 相似文献
8.
Na2O-Al2O3-SiO2 glass-ceramics doped with Er3+ ions were synthesized by the conventional melt quenching technique at a low melting temperature. The samples were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The results show that the main crystalline phase of glass-ceramics is nepheline.The best heat-treatment process is at 520 °C for 2 h. Because the up-conversion luminescence and near infrared luminescence properties of glass doped with Eu3+ are studied in detail. 相似文献
9.
Yuan Xi-ming Xu Yong-sheng Yu Jiang-bo Wang Yong-qian Wang Hong-mei 《武汉理工大学学报(材料科学英文版)》2003,18(1):41-43
Nano fluorescent powder of Y4Al2O9: Eu3+ was synthesized by sol-gel method. The XRD shows that the product prepared at 900°C is pure-phase Y4Al2O9: Eu3+. The Y4Al2O9 powder is nano-size crystal testified by BF and ED analysis of TEM. The grain diameter of Y4Al2O9 is in the range between 20 and 50nm, and its average is 30 nm. The luminescent spectra show that Eu3+ ious occupy two kinds of sites in Y4Al2O9 crystal lattice. One is in the strict inversion center, and the other is in off lying inversion center. When excited with
UV light (λ=254nm), Y4Al2O9: Eu3+ exhibits an orange emission bond at λ=590 nm due to the5Do→7F1 transition and a red emission band at λ=610 nm due to5Do→7F2 transition.
YUAN Xi-ming: Born in 1951
Funded by Key Scientific and Technological Project of Hubei Province (2001 AA102A03) 相似文献
10.
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
11.
TiO2 films were coated on the surface of diamond particles using a sol-gel method. The effects of heat treatment temperature on the morphology, phase composition and chemical bond of diamond particles coated with TiO2 films were investigated through SEM, TEM, X-ray diffraction analysis, Raman spectroscopy, FTIR, and XPS. The results showed that when being heat-treated at 600 °C, the amorphous TiO2 film transfered to the anatase film which bonded well with diamond substrate. Meanwhile, the Ti-O-C bond formed between TiO2 film and diamond substrate. When being heat-treated at 800 °C, TiO2 film was still anatase, and partial diamond began to graphitize. The graphitizated carbon could also form the Ti-O-C bond with TiO2 film, although TiO2 film would tend to crack in this case. 相似文献
12.
MeiYa Li Ling Pei Jun Liu BenFang Yu DongYun Guo XiaoHua Sun XingZhong Zhao 《中国科学E辑(英文版)》2008,51(11):1843-1849
Ferroelectric Bi3.25La0.75Ti3O12 (BLT) and Bi3.15Nd0.85Ti3O12 (BNT) thin films were fabricated on Pt/TiO2/SiO2/Si (100) substrates by a modified sol-gel technique. X-ray diffraction indicated that these films were of single phase with
random polycrystalline orientations. The surface morphologies of the films were observed by scanning electron microscope,
showing uniform, dense films with grain size of 50–100 nm. Well-saturated hysteresis loops of the films were obtained in metal-ferroelectric-metal
type capacitors with Cu top electrodes at an applied voltage of 400 kV/cm, giving the remanent polarization (2P
r) and coercive field (2E
c) values of the films of 25.1 μC/cm2 and 203 kV/cm for BLT, and 44.2 μC/cm2 and 296 kV/cm for BNT, respectively. Moreover, these capacitors did not show fatigue behaviors after up to 1.75×1010 switching cycles at the test frequency of 1 MHz, suggesting a fatigue-free character. The influences of the La3+ and Nd3+ doping on the properties of the films were comparatively discussed.
Supported by the National Key Basic Research and Development Program of China (Grant No. 2006CB932305) and the Natural Science
Foundation of Hubei Province, China (Grant No. 2004ABA082) 相似文献
13.
High refractive index TiO2 thin films were deposited on BK7 glass by reactive electron—beam (REB) evaporation at pressure of 2×10−2 Pa, deposition rate of 0.2 nm/s and at various substrate temperatures from 120°C to 300°C. The refractive index and the thickness
of the films were measured by visible spectroscopic ellipsometry (SE) and determined from transmission spectra. Optical properties
and structure features were characterized by UV-VIS, SEM and XRD, respectively. The measurement and analysis on transmission
spectra of all samples show that with the substrate temperature increasing from 120°C to 300°C, the refractive indices of
thin films increase from 1.7 to 2.1 and the films after heat treatment have higher refractive indices due to its crystallizing.
The XRD analysis results indicate that the structure of TiO2 thin films deposited on BK7 glass at substrate temperatures of 120°C, 200°C and 300°C is amorphous, after post-annealing
under air condition at 400°C for 1 hour, the amorphous structure is crystallized, the crystal phase is of 100% anatase with
strong preferred orientation (004) and the grain size of crystalline is within 3.6–8.1 nm, which is consistent with results
from SEM observation.
WANG Xue-hua: Born in 1976.
Funded by the Youth Project Foundation of Hubei Provincial Education Department (No. 2003B00) 相似文献
14.
胡秀丽 《武汉理工大学学报(材料科学英文版)》2017,32(1):67-75
Ag loaded mesoporous silica-embedded TiO2 nanocomposites were successfully synthesized via two different routes, including one-pot solvothermal method and solvothermal-chemical reduction method, both using Titanium (IV) n-butoxide (Ti(OC4H9)4) as a precursor, formic acid as a solvent and reducing agent, silver nitrate as a silver source and tetraethyl silicate (TEOS) as a stabilizer. The transmission electron microscopic (TEM) images showed that silica-embedded anatase TiO2 sample exhibited approximately rhombic shape and Ag nanoparticles could be embedded into the nanocomposites or deposited on the surface with high dispersion. The N2 adsorption-desorption isotherms indicated that the silica-embedded anatase TiO2 had obvious mesoporous structure with a BET specific surface area of 203.5 m2·g-1. All Ag loaded silica-embedded TiO2 composites showed a higher photocatalytic H2-generation activity from water splitting under simulative solar light irradiation than that of TiO2 products. The maximum H2 production rate (6.10 mmol·h-1·g-1) was obtained over 2% Ag/silica-embedded TiO2 nanocomposites (2% Ag/MST) prepared by solvothermal-chemical reduction method, which was 20 times that achieved on the silica-embedded TiO2 sample. The enhanced photocatalytic H2-evolution activity of Ag loaded mesoporous silica-embedded TiO2 nanocomposites can be attributed to the multi-function of surface Ag co-catalyst, mesoporous structure, and embedding of silica. 相似文献
15.
Bai ShouLi Tong ZhangFa Li DianQing Huang XiaoWei Luo RuiXian Chen AiFan 《中国科学E辑(英文版)》2007,50(1):18-26
The nanocomplex oxides of Sn-In and Sn-In-Ti were prepared by controlled co-precipitation method as sensing materials of semiconductor gas sensors for detection of CO, CH4 and NO2. Through manipulating the Sn/In cation ratio, metal salt total concentration, precipitation pH value and aging time, the nanocrystalline powders were successfully derived with chemical homogeneity and superior thermal stability, compared with the single component oxides. The particle size and morphology, surface area, and thermal and phase stabilities were characterized using TEM, TG-DTA, BET and XRD. The sensing tests showed that the Sn-In composites exhibit high sensitivity and selectivity for CO and NO2. The introduction of TiO2 enhanced CH4 sensitivity and selectivity, particularly, additives of Pd and Al2O3 as a dopant and surface modification greatly enhanced the sensing properties. The sensitivity depended on the composition of composites, calcination temperature and operating temperature. The optimal values were (25%In2O3- 75%SnO2)-20%TiO2 for ternary composite, 600 and 300℃, respectively. Temperature-programmed desorption (TPD) studies were employed to explain the gas adsorption behavior displayed by the surface of nanocomposites and X-ray photoelectron spectroscopic (XPS) analysis was used to confirm the electronic interactions existing between oxide components. The sensing mechanism of the nanocomposites was attributed to chemical and electronic synergistic effects. 相似文献
16.
The single-phrase Ba(Mgl/3Nb2/3)O3(BMN) powder was saccessfully prepared by the KCImolten salt synthesis(MSS) method. The temperature for single-phase BMN powders by MSS was about 400℃ lower than that by the solid-phase method. The average particle size (APS) was about 0.91,u.m at 900℃ and increased with increasing synhesis temperature. Based on the APS, the activation energy for particle growth in theMSS, whose value was 64. 1kJmol^-1.was attained. The sinterability of the powder prepared by MSS method wasbetter than that pretared by solid-phase method. 相似文献
17.
A coprecipitation/hydrothermal route was utilized to fabricate pure phase BiFeO3 powders using FeCl3·6H2O and Bi(NO3)3·5H2O as starting materials, ammonia as precipitant and NaOH as mineralizer. The synthesized powders were characterized by XRD, SEM and DSC-TG analysis. In the process, single-phase BiFeO3 powders could be obtained at a hydrothermal reaction temperature of 180 ℃, with NaOH of 0.15 mol/L, in contrast to 200 ℃ and 4 mol/L for conventional hydrothermal route. Meanwhile, the micro-morphology of synthesized BiFeO3 powders changed with different reaction temperatures and concentrations of NaOH. The N6el temperature, Curie temperature and decomposition temperature of the synthesized BiFeO3 powders were detected to be 301 ℃, 828 ℃ and 964 ℃, respectively. The hydrothermal reactions mechanism to fabricate BiFeO3 powders were discussed based on the in-situ transformation process. 相似文献
18.
Red phosphor K2LiAlF6:Mn4+ has been synthesized by a cation-exchange method in HF solution. To optimize their optical properties, phosphors were synthesized using different reaction conditions. The K2LiAlF6:0.5%Mn4+ synthesized at 20°C for 4 h shows the highest luminescence intensity. The temperature-dependent emission intensity of the phosphor was investigated, and it was found to exhibit good thermal stability, making it a promising red phosphor candidate for warm WLEDs. 相似文献
19.
A novel lanthanum and sulfur co-doped TiO2 photocatalyst was synthesized by precipitation- dipping method, and characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM) and UV-Vis diffuse reflectance spectroscopy. Compared with the S-doped TiO, La-doped TiO2 and the standard Degussa P25 photocatalysts, the lanthanum and sulfur co-doped TiO2 photocatalyst (the molar percentage of La is 3.0%) calcined at 450 ℃ for 2 h showed the strongest absorption for visible light and highest activities for degradation of reactive blue 19 dye in aqueous solution under visible light(λ〉400 nm) irradiation. It was also discovered that the co-doping of lanthanum and sulfur hindered the aggregation and growth of TiO2 particles, and the doping of lanthanum reduced slightly the phase transition temperature ofTiO2 from anatase to rutile. 相似文献
20.
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