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1.
LiAl 0.23Mn 1.77O 4 was synthesized by high temperature solid-state reaction. The structure and morphology of LiAl 0.23Mn 1.77O 4 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The supercapacitive performances of LiAl 0.23Mn 1.77O 4 materials were studied using galvanostatic charge/discharge measurements, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods in 2 mol L −1 (NH 4) 2SO 4 solution. The results show that the LiAl 0.23Mn 1.77O 4 electrode exhibits typical supercapacitive characteristics in aqueous (NH 4) 2SO 4 electrolyte. The specific capacitance is up to 185 F g −1 at current density of 2 mA cm −2. The ohmic resistance ( Rsol) is only 0.22 Ω. Besides, the electrodes showed a stable cycle life in the potential range of 0–1.0 V and retained 93% of initial specific capacitance over 100 cycles. 相似文献
2.
Sol–gel derived Bi 2Ti 2O 7 ceramic powders have been prepared from methoxyethoxides of bismuth and titanium (molar ratio of Ti/Bi = 1.23 and water/alkoxides = 1.31). The Bi 2Ti 2O 7 phase was stable at a low temperature (700 °C), but it then transformed into mixed phases of Bi 4Ti 3O 12 and Bi 2Ti 4O 11 at 850–1150 °C. The single phase of Bi 2Ti 2O 7 reoccurred at 1200 °C. Dielectric properties and ferroelectric behavior of samples sintered at 1150 and 1200 °C were examined. Under frequency of 1 MHz, samples sintered at 1150 and 1200 °C had a dielectric constant of 101.3 and 104.2, and a loss tangent of 0.0193 and 0.0145, respectively. Only the sample sintered at 1150 °C showed ferroelectric behavior, where remanent polarization is 3.77 μC cm −2 and coercive field is 24 kV cm −1. Thus, the Bi 2Ti 2O 7 did not exhibit ferroelectricity, but the mixed phase of Bi 4Ti 3O 12 and Bi 2Ti 4O 11 did. 相似文献
3.
Nanosized lead oxide particles were prepared by thermal decomposition of lead hydroxycarbonate synthesized under microwave irradiation. Urea and lead nitrate were used as the starting materials. Microstructure and morphology of the products were investigated by means of XRD, AFM, TEM, and IR absorption spectra. The results indicated that well crystallized, finely dispersed and spherical -PbO nanoparticles with a size of ca. 30 nm were obtained. Meanwhile, an orthogonal phase β-PbO with a size of ca. 38 nm was also obtained when the calcinations temperature was up to 600 °C. In addition, a Pb(II)-selective electrode based on cellulose acetate was prepared using nanosized -PbO powders synthesized. The electrode exhibited a Nernstian slope of 29±1 mV per decade in a linear range of 2.5×10 −5 mol L −1 to 1.0×10 −1 mol L −1 for Pb 2+ ion. The detection limit of this electrode is down to 8.0×10 −6 mol L −1. This sensor has a short response time of about 10 s and could be used in a pH range of 2.0–8.0. High selectivity was obtained over a wide variety of metal ions. 相似文献
4.
Radiation field reduction in the primary heat transport (PHT) system of water-cooled reactors can be achieved by ‘dilute chemical decontamination (DCD)’ process. The corrosion behaviour of carbon steel has been studied in the absence and presence of different concentrations of cinnamaldehyde in 4.76 mM L −1 of citric acid for different immersion times (6 h and 24 h) at 30 °C using weight loss, potentiodynamic polarization and impedance measurements. Cinnamaldehyde has given an inhibition efficiency of about 90% at 15.15 mM L −1 and inhibition efficiency is decreased to 82% when duration of immersion increased from 6 h to 24 h. Electrochemical studies follow the same trend as those observed in weight loss measurements. The formation of the adsorbed inhibitor film on the carbon steel was further confirmed by FTIR studies. 相似文献
5.
The corrosion behaviour of tin in different concentrations of citric acid solutions (0.3–1.0 M, pH=1.8) was studied at 30 °C by potentiodynamic technique. The E/ I profiles exhibit an active passive behaviour. The active dissolution involves one anodic peak A associated with a dissolution of the metals as Sn(II) species. The passivity is due to the formation of thin film of SnO 2 and or Sn(OH) 4 on the anode surface. The cathodic sweep shows a small peak C related to the reduction of the passive film. The peak current density Ip of peak A increases with increasing both acid concentration and sweep rate. The effects of adding increasing concentrations of Na2CrO4, NaMoO4, NaNO3 and NaNO2 on the corrosion of tin in 0.5 M citric acid at 30 °C were investigated. Both CrO42− and MoO42− ions inhibit the corrosion of tin and the extent of inhibition enhances with their concentrations. Addition of either NO3− or NO2− accelerates the corrosion of tin. NO3− ions are more aggressive than NO2− ions. 相似文献
6.
Ti–6Al–4V (Ti64) sheet specimens were cathodically hydrogenated in sulfuric acid solution at ambient conditions. The hydrogenated specimens were then sent to go through the designed thermohydrogen processing (THP) twice to obtain a nano-sized grain structure. The average grain size of resulted microstructure was found to be 10–20 nm obtained by TEM. Qualitative and quantitative analyses performed by employing X-ray diffractometry (XRD) and elemental analysis (EA) showed that the addition of As 2O 3 as hydrogenation promoter in electrolyte significantly increased the hydrogen uptake. The high concentration of hydrogen arising from promoter action is the key factor in grain refinement. The optimal processing parameter found for grain-refining Ti64 was: (1) electrolytic hydrogenation at 100 mA cm −2 for 3 h in 1 N H 2SO 4(aq) by adding 0.1 g L −1 As 2O 3; (2) β transformation carried out at 850 °C for 1 h in air furnace, followed by a furnace cooling to 590 °C and held for 6 h; (3) oxide film removed and then dehydrogenated at 650 °C and 1.0 × 10 −6 Torr for 10 h; (4) repeated the same processes once more. 相似文献
7.
Thin films of the system xAl 2O 3–(100 − x)Ta 2O 5–1Er 2O 3 were prepared by a sol–gel method and a dip-coating technique. The influences of the composition and the crystallization of the films on Er 3+ optical properties were investigated. Results of X-ray diffraction indicated that the crystallization temperature of Ta 2O 5 increased from 800 to 1000 °C with increased values of x. In crystallized films, the intensities of the visible fluorescence and upconversion fluorescence tend to decrease with an increase in x values, due to the high phonon energy of Al 2O 3; the strongest fluorescence is observed in a crystallized film for x = 4 heat treated at 1000 °C. In amorphous films obtained by heat treatment at relatively low temperatures the Er 3+ fluorescence could not be observed because strong fluorescence from organic residues remaining in the films thoroughly covered the Er 3+ fluorescence. On the other hand, the Er 3+ upconversion fluorescence in the amorphous films was observed to be stronger than that in the crystallized films. The strongest upconversion fluorescence is observed in an amorphous film for x = 75 heat treated at 800 °C. 相似文献
8.
Bi 2O 3·B 2O 3 glasses doped with rare-earth oxides (RE 2O 3) (RE 3+ = La 3+, Pr 3+, Sm 3+, Gd 3+, Er 3+ and Yb 3+) were prepared by the melting–quenching method. The relationships between composition and properties were demonstrated by IR, DSC, XRD and SEM analysis. The results show that the network structure resembles that of undoped Bi 2O 3·B 2O 3 glass, composing of [BO 3], [BO 4] and [BiO 6] units. RE 2O 3 stabilizes the glass structure as a modifier. Transition temperature ( Tg) increases linearly with cationic field strength (CFS) of RE 3+. La 2O 3, Pr 2O 3, Sm 2O 3 and Gd 2O 3 are benefit to promote the formation of BiBO 3 crystal. When Er 2O 3 and Yb 2O 3 are introduced, respectively, the main crystal phase changes to Bi 6B 10O 24. Transparent surface crystallized samples are obtained by reheating at 460–540 °C for 5 h. In this case, needle like BiBO 3 crystal or rare-earth-doped BiBO 3 crystal (Pr xBi 1−xBO 3 and Gd xBi 1−xBO 3) are observed, which is promising for non-linear optical application. 相似文献
9.
The Aurivillius type bismuth layer-structured compound potassium lanthanum bismuth titanate (K 0.5La 0.5Bi 4Ti 4O 15) is synthesized using conventional solid-state processing. The phase analysis is performed by X-ray diffraction (XRD) and the microstructural morphology is conducted by scanning electron microscopy (SEM). The ferroelectric, dielectric and piezoelectric properties of K 0.5La 0.5Bi 4Ti 4O 15 (KLBT) ceramics are investigated in detail. The remnant polarization ( Pr) and coercive field ( Ec) are found to be 8.6 μC cm −2 and 60 kV cm −1, respectively. The Curie temperature Tc and piezoelectric coefficient d33 are 413 °C and 18 pC N −1, respectively. 相似文献
10.
GaOOH:Eu 3+ nanorods with different aspect ratios were prepared by hydrothermal method at 140 °C. - and β-Ga 2O 3:Eu 3+ were converted from as-prepared GaOOH:Eu 3+ particles by calcination at 500 and 850 °C, respectively. The products were characterized with X-ray diffraction (XRD), transmission electron microscope (TEM) and photoluminescence (PL). Results show that solution pH values play a key role in the formation of the GaOOH:Eu 3+ powders with different morphologies and - and β-Ga 2:Eu 3+ inherit the morphology of GaOOH:Eu 3+ exactly. The photoluminescence characteristics of β-Ga 2O 3:Eu 3+ were also investigated. Experimental results reveal that the color purity of β-Ga 2O 3:Eu 3+ nanorods with high aspect ratio is enhanced in comparison with β-Ga 2O 3:Eu 3+ nanorods with low aspect ratio. 相似文献
11.
We report on the properties of (1− x)SrBi 2Ta 2O 9– xBi 3TaTiO 9 solid solution thin films for ferroelectric non-volatile memory applications. The solid solution thin films fabricated by modified metalorganic solution deposition technique showed much improved properties compared to SrBi 2Ta 2O 9. A pyrochlore free crystalline phase was obtained at a low annealing temperature of 600°C and grain size was found to be considerably increased for the solid solution compositions. The film properties were found to be strongly dependent on the composition and annealing temperatures. The measured dielectric constant of the solid solution thin films was in the range 180–225 for films with 10–50% of Bi 3TaTiO 9 content in the solid solution. Ferroelectric properties of (1− x)SrBi 2Ta 2O 9– xBi 3TaTiO 9 thin films were significantly improved compared to SrBi 2Ta 2O 9. For example, the observed remanent polarization (2 Pr) and coercive field ( Ec) values for films with 0.7SrBi 2Ta 2O 9–0.3Bi 3TaTiO 9 composition, annealed at 650°C, were 12.4 μC/cm 2 and 80 kV/cm, respectively. The solid solution thin films showed less than 5% decay of the polarization charge after 10 10 switching cycles and good memory retention characteristics after about 10 6 s of memory retention. The improved microstructural and ferroelectric properties of (1− x)SrBi 2Ta 2O 9– xBi 3TaTiO 9 thin films compared to SrBi 2Ta 2O 9, especially at lower annealing temperatures, suggest their suitability for high density FRAM applications. 相似文献
12.
Synthesis and single crystal structure are reported for a new gadolinium acid diphosphate tetrahydrate HGdP 2O 7·4H 2O. This salt crystallizes in the monoclinic system, space group P2 1/ n, with the following unit-cell parameters: a = 6.6137(2) Å, b = 11.4954(4) Å, c = 11.377(4) Å, β = 87.53(2)° and Z = 4. Its crystal structure was refined to R = 0.0333 using 1783 reflections. The corresponding atomic arrangement can be described as an alternation of corrugated layers of monohydrogendiphosphate groups and GdO 8 polyhedra parallel to the ( ) plane. The cohesion between the different diphosphoric groups is provided by strong hydrogen bonding involving the W4 water molecule. IR and Raman spectra of HGdP2O7·4H2O confirm the existence of the characteristic bands of diphosphate group in 980–700 cm−1 area. The IR spectrum reveals also the characteristic bands of water molecules vibration (3600–3230 cm−1) and acidic hydrogen ones (2340 cm−1). TG and DTA investigations show that the dehydration of this salt occurs between 79 and 900 °C. It decomposes after dehydration into an amorphous phase. Gadolinium diphosphate Gd4(P2O7)3 was obtained by heating HGdP2O7·4H2O in a static air furnace at 850 °C for 48 h. 相似文献
13.
The microstructure, electrical properties, dielectric characteristics, and DC-accelerated aging behavior of the ZnO–V 2O 5–MnO 2 system sintered were investigated for MnO 2 content of 0.0–2.0 mol% by sintering at 900 °C. For all samples, the microstructure of the ZnO–V 2O 5–MnO 2 system consisted of mainly ZnO grain and secondary phase Zn 3(VO 4) 2. The incorporation of MnO 2 to the ZnO–V 2O 5 system was found to restrict the abnormal grain growth of ZnO. The nonlinear properties and stability against DC-accelerated aging stress improved with the increase of MnO 2 content. The ZnO–V 2O 5–MnO 2 system added with MnO 2 content of 2.0 mol% exhibited not only a high nonlinearity, in which the nonlinear coefficient is 27.2 and the leakage current density is 0.17 mA/cm 2, but also a good stability, in which %Δ E1 mA = −0.6%, %Δ = −26.1%, and %Δtan δ = +22% for DC-accelerated aging stress of 0.85 E1 mA/85 °C/24 h. 相似文献
14.
Ferroelectric SrBi 2Ta 2O 9/SrBi 2Nb 2O 9 (SBT/SBN) multilayer thin films with various stacking periodicity were deposited on Pt/TiO 2/SiO 2/Si substrate by pulsed laser deposition technique. The X-ray diffraction patterns indicated that the perovskite phase was fully formed with polycrystalline structure in all the films. The Raman spectra showed the frequency of the O–Ta–O stretching mode for multilayer and single layer SrBi 2(Ta 0.5Nb 0.5) 2O 9 (SBNT) samples was 827–829 cm −1, which was in between the stretching mode frequency in SBT (813 cm −1) and SBN (834 cm −1) thin films. The dielectric constant was increased from 300 (SBT) to 373 at 100 kHz in the double layer SBT/SBN sample with thickness of each layer being 200 nm. The remanent polarization (2 Pr) for this film was obtained 41.7 μC/cm 2, which is much higher, compared to pure SBT film (19.2 μC/cm 2). The coercive field of this double layer film (67 kV/cm) was found to be lower than SBN film (98 kV/cm). 相似文献
15.
通过球磨分散法和熔融共混法制得纳米Sb 2O 3/溴化环氧树脂-聚丙烯(BEO-PP)阻燃复合材料试样。采用XRD、DSC、拉伸和冲击性能测试,研究了纳米Sb 2O 3/BEO-PP阻燃复合材料的力学性能及其增强机制。研究结果表明:采用球磨法改性后的纳米Sb 2O 3颗粒在PP基体中的分散性和黏结性能得到明显改善;纳米Sb 2O 3颗粒的加入可改善PP基复合材料的强韧性;随着纳米Sb 2O 3质量分数的升高,纳米Sb 2O 3/BEO-PP复合材料的力学性能呈现出先升后降的趋势,PP基体的结晶度逐渐增高;当纳米Sb 2O 3颗粒添加量为2wt%时,纳米Sb 2O 3/BEO-PP复合材料表现出优异的综合性能。 相似文献
16.
Zirconium doped indium oxide thin films were deposited by the atomic layer deposition technique at 500 °C using InCl 3, ZrCl 4 and water as precursors. The films were characterised by X-ray diffraction, energy dispersive X-ray analysis and by optical and electrical measurements. The films had polycrystalline In 2O 3 structure. High transparency and resistivity of 3.7×10 −4 Ω cm were obtained. 相似文献
17.
制备水基亚微米Sb 2O 3浆液,用聚乙烯醇(PVA)作空间稳定剂对Sb 2O 3表面修饰后,与氯丁胶乳(CRL)复合制备一种阻燃的PVA修饰Sb 2O 3/CRL(Sb 2O 3-PVA/CRL)复合材料。探究了最优修饰工艺及其对Sb 2O 3-PVA/CRL分散稳定性的影响规律,从粒径分布、FTIR和DTA-TGA等角度探讨PVA修饰明显提升Sb 2O 3分散稳定性的作用机制。结果表明,研钵研磨使Sb 2O 3粒径微细化,是制备亚微米Sb 2O 3的有效手段;PVA修饰Sb 2O 3粉末在3 447 cm -1处的-OH伸缩振动特征峰减弱,1 091 cm -1处的C-O特征吸收峰消失,推测化学键力是PVA包覆Sb 2O 3粉末的重要方式;获得最优分散稳定性的修饰工艺为:PVA与Sb 2O 3质量比为2%、反应温度为90℃、反应时间为30 min;采用最优修饰工艺制备的Sb 2O 3-PVA/CRL复合材料静置6 h内有好的分散稳定性。 相似文献
18.
为实现高岭土(Kaolin)在Cu 2+废水处理中的实际应用,采用球磨方法制备了剥离Kaolin,并通过氧化沉淀法制备了Fe 3O 4/Kaolin磁性复合材料。通过激光粒度分析仪、SEM、XRD对Fe 3O 4/Kaolin磁性复合材料的形貌及组成进行表征,并通过测试Fe 3O 4/Kaolin磁性复合材料对Cu 2+的饱和吸附量和磁分离回收率,确定了当Kaolin球磨4.0 h、掺量为3.0 g时所制备的Fe 3O 4/Kaolin磁性复合材料对Cu 2+的吸附性能最佳,平衡吸附量为17.98 mg/g。磁滞回线结果表明,Fe 3O 4/Kaolin磁性复合材料具有较好的磁响应性,饱和磁化强度约为16.19 emu/g。此外,采用Langmuir和Freundlich吸附等温式对Fe 3O 4/Kaolin磁性复合材料的吸附数据进行拟合,结果表明,Fe 3O 4/Kaolin磁性复合材料对Cu 2+的吸附行为基本符合Langmuir吸附等温模型和Freundlich吸附等温模型,既存在单分子层吸附,也存在多分子层吸附。 相似文献
19.
Solid solutions of Bi 3(Nb 1−xTa x)O 7 ( x = 0.0, 0.3, 0.7, 1) were synthesized using solid state reaction method and their microwave dielectric properties were first reported. Pure phase of fluorite-type could be obtained after calcined at 700 °C (2 h) −1 between 0 ≤ x ≤ 1 and Bi 3(Nb 1−xTa x)O 7 ceramics could be well densified below 990 °C. As x increased from 0.0 to 1.0, saturated density of Bi 3(Nb 1−xTa x)O 7 ceramics increased from 8.2 to 9.1 g cm −3, microwave permittivity decreased from 95 to 65 while Qf values increasing from 230 to 560 GHz. Substitution of Ta for Nb modified temperature coefficient of resonant frequency τf from −113 ppm °C −1 of Bi 3NbO 7 to −70 ppm °C −1 of Bi 3TaO 7. Microwave permittivity, Qf values and τf values were found to correlate strongly with the structure parameters of fluorite solid solutions and the correlation between them was discussed in detail. Considering the low densified temperature and good microwave dielectric proprieties, solid solutions of Bi 3(Nb 1−xTa x)O 7 ceramics could be a good candidate for low temperature co-fired ceramics application. 相似文献
20.
Novel pure and cobalt-doped magnesium borate crystals (Mg 3B 2O 6) have been grown successfully by the Czochralski technique for the first time. Crystal growth, X-ray powder diffraction (XRD) analysis, absorption spectrum, fluorescence spectrum as well as fluorescence decay curve of Co 2+:Mg 3B 2O 6 (MBO) were described. From the absorption peaks for the octahedral Co 2+ ions, the crystal-field parameter Dq and the Racah parameter B were estimated to be 943.3 cm −1 and 821.6 cm −1, respectively. The fluorescence lifetime of the transition 4T1( 4P) → 4T2 centered at 717 nm was measured to be 9.68 ms. 相似文献
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