The single-phase BiFeO3 powders were prepared by sol-gel method with the starting materials of bismuth nitrate and ferric nitrate, and the effect of the calcined temperature on the phases of BiFeO3 samples was studied...The single-phase BiFeO3 powders were prepared by sol-gel method with the starting materials of bismuth nitrate and ferric nitrate, and the effect of the calcined temperature on the phases of BiFeO3 samples was studied. The x-ray diffraction (XRD)showed that the single-phase BiFeO3 powders were obtained with a calcined temperature of 700 ℃. The scanning electron microscope(SEM)analysis indicated that the grain size was around 500 nm in single-phase BiFeO3 powders, and uniform particle size distribution. The FT-IR spectra showed that the BiFeO3 powders began to crystallize at 500℃.展开更多
Two series of perovskite-type oxides with composition (La_(1-x))Sr_xFeO_3(x≤0.8)and La_(1-x)Sr_xFe_(1-y)Co_yO_3(x=0.2; y=0.2, 0.4)powder productions were synthesized by EDTA complexing sol-gel method. The products we...Two series of perovskite-type oxides with composition (La_(1-x))Sr_xFeO_3(x≤0.8)and La_(1-x)Sr_xFe_(1-y)Co_yO_3(x=0.2; y=0.2, 0.4)powder productions were synthesized by EDTA complexing sol-gel method. The products were characterized by XRD, TEM, SEM, BET method(N_2 adsorption)and laser granularity analysis for different synthesis conditions to obtain the optimum conditions for the preparation process. Single-phased, uniform perovskite-type oxides with small particle size were obtained by EDTA sol-gel process with high stability and repeatability, and the process temperature is much lower than that of solid state reaction method.展开更多
yb3+/Dy3+ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results...yb3+/Dy3+ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4C9/2→ 6H13/2, 4C9/2→ 6Hll/2, 4115/2 → 6H13/2, and 4F9/2 →6Hll/2 transitions of Dy3+, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3+ and Dy3+ is discussed.展开更多
(Fe7Co3)0.15(SiO2)0.85 granular alloy solid was prepared successfully using sol-gel method. The samples with different reducing temperatures were investigated by X-ray diffractometer(XRD),transmission electron microgr...(Fe7Co3)0.15(SiO2)0.85 granular alloy solid was prepared successfully using sol-gel method. The samples with different reducing temperatures were investigated by X-ray diffractometer(XRD),transmission electron micrography(TEM) and vibrating sample magnetometer(VSM). The av-erage particIe sizes of the samples were also calculated from Scherrer formula. The magnetic properties of (Fe7Co3 )o. 15 (SiO2)0.85 were studied in detail.展开更多
Nanometer Al_2O_3 is one of new types of functional materials with broad application and development prospects in the future. The basic principle and ways of nanometer Al_2O_3 fabricated using sol-gel technique were i...Nanometer Al_2O_3 is one of new types of functional materials with broad application and development prospects in the future. The basic principle and ways of nanometer Al_2O_3 fabricated using sol-gel technique were introduced, and the factors affecting nanometer Al_2O_3 fabricated using sol-gel method were analyzed. The progress in research on nanometer Al_2O_3 and the application fields of nanometer Al_2O_3 were reviewed. The existing problems and the problems prospect for nanometer Al_2O_3 were pointed out.展开更多
The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 ...The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 in the raw materials of Li3V2(PO4)3.The XRD analysis shows that the Al-substituted Li3V2(PO4)3 has the same monoclinic structure as the un-substituted Li3V2(PO4)3.The SEM images show that Al-substituted Li3V2(PO4)3 has regular and uniform particles.The electrochemical measurements show that Al-substitution can improve the rate capability of cathode materials.The Li3Al0.05V1.95(PO4)3 sample shows the best high-rate performance.The discharge capacity at 1C rate is 119 mA·h/g with 30th capacity retention rate about 92.97%.The electrode reaction reversibility and electronic conductivity are enhanced,and the charge transfer resistance decreases through Al-substitution.The improved electrochemical performances of Al-substituted Li3V2(PO4)3 cathode materials offer some favorable properties for their commercial application.展开更多
Bi3.25La0.75Ti3O12(BLT)thin films were prepared on Pt/Ti/SiO2/Si substrate by the sol-gel method.The effect of annealing on their structures and ferroelectric properties was investigated.The XRD patterns indicate th...Bi3.25La0.75Ti3O12(BLT)thin films were prepared on Pt/Ti/SiO2/Si substrate by the sol-gel method.The effect of annealing on their structures and ferroelectric properties was investigated.The XRD patterns indicate that the BLT films annealed at different temperatures are randomly orientated and the single perovskite phase is obtained at 550℃.The remmant polarization increnses and the coercive field decreases with the annealing temperature increasing.The leakage current density of the BLT films annealed at 700℃ is about 5.8×10^-8A/cm^2 at the electrie field of 250kv/cm.展开更多
A precursor of BaCe0.5Zr0.4Y0. 1O3-α electrolytes was synthesized by the sol-gel method and sintered at temperature which were 150 - 250 ℃ lower than by solid state reaction. The AC impedance spectrums of electrolyt...A precursor of BaCe0.5Zr0.4Y0. 1O3-α electrolytes was synthesized by the sol-gel method and sintered at temperature which were 150 - 250 ℃ lower than by solid state reaction. The AC impedance spectrums of electrolytes were measured by AUTOLAB PGSTA30 electrochemical measuring device at different temperatures. The conductivities of the electrolytes are 1.62×10^-4 - 6.43×10^-3, 2.52×10^-5 - 3.73×10^-3S·cm^-1 in the temperature range of 350-800℃. The activity energies are 0.54 and 0.84 eV. At the same time BaCe0.9Y0.1O3-α was prepared by direct solid state reaction. The conductivity of BaCe0.9Y0.1O3-α is 1 × 10^-4- 4×10^-3 S·cm^-1 and the activation energy is 0.50 eV at the same condition. The results show that conduction of electrolyte prepared by sol-gel method is higher than the one by solid state reaction. As far as BaCe0.9Y0.1O3-α concerned, its conductivity of the Zr-substituted specimens is decreased.展开更多
Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO...Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.展开更多
The aim of this study was to develop a method to prepare WO<sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span>&l...The aim of this study was to develop a method to prepare WO<sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> film which has high anticorrosion property when it was coated on type 304 stainless steel. A series of WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-modified TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sols were synthesized by peroxo-sol gel method using TiCl</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> and Na</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">WO</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> as the starting materials. TiCl</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> was converted to Ti(OH)</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> gel. H</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> and Na</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">WO</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> were added in Ti(OH)</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> solution and heated at 95<span style="white-space:normal;">°</span>C. The WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sol was transparent, in neutral (pH^7) solution, stable suspension without surfactant, nano-crystallite and no annealing is needed after coating, and very stable for 2 years in stock. WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sol was formed with anatase crystalline structure. These sols were characterized by XRD, TEM, and XPS. The sol was used to coat on stainless steel 304 by dip-coating. The WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> was anatase in structure as characterized by X-ray diffraction. There were no WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> XRD peaks in the WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sols, indicating that WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> particles were very small, possibly incorporating into TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> structure, providing the amount of WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> was very small. The TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> particles were rhombus shape. WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> had smaller size area than pure TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">. The SEM results showed that the film coated on the glass substrate was very uniform. All films were nonporous and dense films. Its hardness reached 2 H after drying at 100<span style="white-space:normal;">°</span>C, and reached 5 H after annealing at 400<span style="white-space:normal;">°</span>C. The WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> film coated on 304 stainless steel had better anticorrosion capability than the unmodified TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> film under UV light illumination. The optimum weight ratio of TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">: WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> was 100:4.</span>展开更多
An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxi...An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural and crystallographic properties of Al2O3 supports. Only the formation of γ-Al2O3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al2O3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO3)3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO3)3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.展开更多
采用水热法在不同条件下制备BiFeO3光催化剂,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外-可见漫反射光谱(UV Vis DRS)等对其进行表征,并以罗丹明B(RhB)溶液为降解物,研究BiFeO3的可见光光催化性能.研究结果表明:制备的BiFeO3光...采用水热法在不同条件下制备BiFeO3光催化剂,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外-可见漫反射光谱(UV Vis DRS)等对其进行表征,并以罗丹明B(RhB)溶液为降解物,研究BiFeO3的可见光光催化性能.研究结果表明:制备的BiFeO3光催化剂具有单一的晶相,粒径为几微米至几十微米,颗粒团聚,吸收的截止波长约为600 nm.BiFeO3颗粒的催化性能表明:中性环境下BiFeO3颗粒对RhB的降解能力很弱,基本对RhB无降解.将体系引入酸性环境,当体系的pH=5时,RhB经过90 min照射,降解率为89.2%;当体系的pH=3时,经过90 min照射,RhB完全降解.说明在模拟太阳光光照下,BiFeO3颗粒对酸性环境下的RhB有良好的光催化降解作用.展开更多
Nanosized 1 at% Sm^(3+)doped Y_(2)O_(3)powders were prepared by an ultrasound assisted sol-gel method.Y_(2)O_(3):Sm^(3+)powders crystallize in Y_(2)O_(3)pure cubic phase and XRD analysis shows that the as-used agitati...Nanosized 1 at% Sm^(3+)doped Y_(2)O_(3)powders were prepared by an ultrasound assisted sol-gel method.Y_(2)O_(3):Sm^(3+)powders crystallize in Y_(2)O_(3)pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite’s shape and mean size.The recorded emission spectra under λ_(em)=600 nm exhibit two absorption bands;the first one is assigned to O^(2-)→Sm^(3+)charge transfer state(CTS) with a maximum absorption at 223 nm,and the second is due to intraconfigurational transition 4f^(5)-4f^(5) of Sm^(3+) with a maximum absorption at 407 nm.The 223 and 407 nm transitions are attributed to characteristics intra-configurational transitions of Sm^(3+).All emission spectra are dominated by reddish/orange luminescence located at 606 nm and assigned to ^(4)G_(5/2)→^(6)H_(7/2) transition.It is found that the photoluminescence intensity of samples obtained under excitation at 407 nm is 60 times smaller than that obtained under 223 nm excitation.Decay time measurements of the ^(4)G_(5/2)→^(6)H_(7/2) luminescence transition indicate that decay time of nano-sized powder is significantly shorter than bulk material one.展开更多
The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X...The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.展开更多
Sol-gel process was adopted to prepare BiFeO3 films.BiFeO3 films were deposited on LaNiO3 coated Si(100) substrates annealed at 500 and 550 ℃,respectively.The X-ray diffraction results reveal that BiFeO3 film has a...Sol-gel process was adopted to prepare BiFeO3 films.BiFeO3 films were deposited on LaNiO3 coated Si(100) substrates annealed at 500 and 550 ℃,respectively.The X-ray diffraction results reveal that BiFeO3 film has a rhombohedrally distorted perovskite structure with space group R3c.The film annealed at 500 ℃ has larger remnant polarization(Pr) of 35.3 μC/cm2.For the film annealed at 550 ℃,smaller remnant polarization of Pr=4.8 μC/cm^2 is observed for its low breakdown electric field.Lower leakage conduction is observed in the film annealed at 500 ℃ at low applied field.展开更多
Nanocrystal SmBO3 powders were synthesized by nitrate-citrate sol-gel combustion method. The phase evolution, morphologies and absorbency of the synthesized powders were characterized by X-ray diffraction (XRD), Fie...Nanocrystal SmBO3 powders were synthesized by nitrate-citrate sol-gel combustion method. The phase evolution, morphologies and absorbency of the synthesized powders were characterized by X-ray diffraction (XRD), Field emission scanning electronic microscope (FESEM), Fourier transform infrared spectroscopy (FFIR) and UV-3101PC spectrophotometer (UVPC), respectively. XRD and FESEM results showed that pure SmBO3 phase was obtained at 750 ℃, with an average original particle size of about 100 nm. FTIR showed that there were apparently concentrated absorbent peaks between 500 and 1400 cm^-1. Moreover, the reflectivity of the powders apparently decreased at the wavelength between 1.05 and 1.15 μm. Therefore, SmBO3 might be a kind of absorbent material for infrared laser.展开更多
The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy...The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively.展开更多
文摘The single-phase BiFeO3 powders were prepared by sol-gel method with the starting materials of bismuth nitrate and ferric nitrate, and the effect of the calcined temperature on the phases of BiFeO3 samples was studied. The x-ray diffraction (XRD)showed that the single-phase BiFeO3 powders were obtained with a calcined temperature of 700 ℃. The scanning electron microscope(SEM)analysis indicated that the grain size was around 500 nm in single-phase BiFeO3 powders, and uniform particle size distribution. The FT-IR spectra showed that the BiFeO3 powders began to crystallize at 500℃.
文摘Two series of perovskite-type oxides with composition (La_(1-x))Sr_xFeO_3(x≤0.8)and La_(1-x)Sr_xFe_(1-y)Co_yO_3(x=0.2; y=0.2, 0.4)powder productions were synthesized by EDTA complexing sol-gel method. The products were characterized by XRD, TEM, SEM, BET method(N_2 adsorption)and laser granularity analysis for different synthesis conditions to obtain the optimum conditions for the preparation process. Single-phased, uniform perovskite-type oxides with small particle size were obtained by EDTA sol-gel process with high stability and repeatability, and the process temperature is much lower than that of solid state reaction method.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11004092) and the Scientific Research Fund of Education Department of Liaoning Province, China (Grant No. 2009A417).
文摘yb3+/Dy3+ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4C9/2→ 6H13/2, 4C9/2→ 6Hll/2, 4115/2 → 6H13/2, and 4F9/2 →6Hll/2 transitions of Dy3+, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3+ and Dy3+ is discussed.
文摘(Fe7Co3)0.15(SiO2)0.85 granular alloy solid was prepared successfully using sol-gel method. The samples with different reducing temperatures were investigated by X-ray diffractometer(XRD),transmission electron micrography(TEM) and vibrating sample magnetometer(VSM). The av-erage particIe sizes of the samples were also calculated from Scherrer formula. The magnetic properties of (Fe7Co3 )o. 15 (SiO2)0.85 were studied in detail.
文摘Nanometer Al_2O_3 is one of new types of functional materials with broad application and development prospects in the future. The basic principle and ways of nanometer Al_2O_3 fabricated using sol-gel technique were introduced, and the factors affecting nanometer Al_2O_3 fabricated using sol-gel method were analyzed. The progress in research on nanometer Al_2O_3 and the application fields of nanometer Al_2O_3 were reviewed. The existing problems and the problems prospect for nanometer Al_2O_3 were pointed out.
基金Project(GuiJiaoRen[2007]71)supported by the Research Funds of the Guangxi Key Laboratory of Environmental Engineering,Protection and Assessment Program to Sponsor Teams for Innovation in the Construction of Talent Highlands in Guangxi Institutions of Higher Learning,China
文摘The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 in the raw materials of Li3V2(PO4)3.The XRD analysis shows that the Al-substituted Li3V2(PO4)3 has the same monoclinic structure as the un-substituted Li3V2(PO4)3.The SEM images show that Al-substituted Li3V2(PO4)3 has regular and uniform particles.The electrochemical measurements show that Al-substitution can improve the rate capability of cathode materials.The Li3Al0.05V1.95(PO4)3 sample shows the best high-rate performance.The discharge capacity at 1C rate is 119 mA·h/g with 30th capacity retention rate about 92.97%.The electrode reaction reversibility and electronic conductivity are enhanced,and the charge transfer resistance decreases through Al-substitution.The improved electrochemical performances of Al-substituted Li3V2(PO4)3 cathode materials offer some favorable properties for their commercial application.
文摘Bi3.25La0.75Ti3O12(BLT)thin films were prepared on Pt/Ti/SiO2/Si substrate by the sol-gel method.The effect of annealing on their structures and ferroelectric properties was investigated.The XRD patterns indicate that the BLT films annealed at different temperatures are randomly orientated and the single perovskite phase is obtained at 550℃.The remmant polarization increnses and the coercive field decreases with the annealing temperature increasing.The leakage current density of the BLT films annealed at 700℃ is about 5.8×10^-8A/cm^2 at the electrie field of 250kv/cm.
文摘A precursor of BaCe0.5Zr0.4Y0. 1O3-α electrolytes was synthesized by the sol-gel method and sintered at temperature which were 150 - 250 ℃ lower than by solid state reaction. The AC impedance spectrums of electrolytes were measured by AUTOLAB PGSTA30 electrochemical measuring device at different temperatures. The conductivities of the electrolytes are 1.62×10^-4 - 6.43×10^-3, 2.52×10^-5 - 3.73×10^-3S·cm^-1 in the temperature range of 350-800℃. The activity energies are 0.54 and 0.84 eV. At the same time BaCe0.9Y0.1O3-α was prepared by direct solid state reaction. The conductivity of BaCe0.9Y0.1O3-α is 1 × 10^-4- 4×10^-3 S·cm^-1 and the activation energy is 0.50 eV at the same condition. The results show that conduction of electrolyte prepared by sol-gel method is higher than the one by solid state reaction. As far as BaCe0.9Y0.1O3-α concerned, its conductivity of the Zr-substituted specimens is decreased.
文摘Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.
文摘The aim of this study was to develop a method to prepare WO<sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> film which has high anticorrosion property when it was coated on type 304 stainless steel. A series of WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-modified TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sols were synthesized by peroxo-sol gel method using TiCl</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> and Na</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">WO</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> as the starting materials. TiCl</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> was converted to Ti(OH)</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> gel. H</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> and Na</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">WO</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> were added in Ti(OH)</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> solution and heated at 95<span style="white-space:normal;">°</span>C. The WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sol was transparent, in neutral (pH^7) solution, stable suspension without surfactant, nano-crystallite and no annealing is needed after coating, and very stable for 2 years in stock. WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sol was formed with anatase crystalline structure. These sols were characterized by XRD, TEM, and XPS. The sol was used to coat on stainless steel 304 by dip-coating. The WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> was anatase in structure as characterized by X-ray diffraction. There were no WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> XRD peaks in the WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> sols, indicating that WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> particles were very small, possibly incorporating into TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> structure, providing the amount of WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> was very small. The TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> particles were rhombus shape. WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> had smaller size area than pure TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">. The SEM results showed that the film coated on the glass substrate was very uniform. All films were nonporous and dense films. Its hardness reached 2 H after drying at 100<span style="white-space:normal;">°</span>C, and reached 5 H after annealing at 400<span style="white-space:normal;">°</span>C. The WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">-TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> film coated on 304 stainless steel had better anticorrosion capability than the unmodified TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> film under UV light illumination. The optimum weight ratio of TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">: WO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> was 100:4.</span>
文摘An aqueous sol-gel method for the synthesis of γ-Al2O3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural and crystallographic properties of Al2O3 supports. Only the formation of γ-Al2O3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al2O3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO3)3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO3)3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.
基金supported by Nuclear Research Center of Algiers(CRNA),Department of Laser,Luminescence Laboratory。
文摘Nanosized 1 at% Sm^(3+)doped Y_(2)O_(3)powders were prepared by an ultrasound assisted sol-gel method.Y_(2)O_(3):Sm^(3+)powders crystallize in Y_(2)O_(3)pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite’s shape and mean size.The recorded emission spectra under λ_(em)=600 nm exhibit two absorption bands;the first one is assigned to O^(2-)→Sm^(3+)charge transfer state(CTS) with a maximum absorption at 223 nm,and the second is due to intraconfigurational transition 4f^(5)-4f^(5) of Sm^(3+) with a maximum absorption at 407 nm.The 223 and 407 nm transitions are attributed to characteristics intra-configurational transitions of Sm^(3+).All emission spectra are dominated by reddish/orange luminescence located at 606 nm and assigned to ^(4)G_(5/2)→^(6)H_(7/2) transition.It is found that the photoluminescence intensity of samples obtained under excitation at 407 nm is 60 times smaller than that obtained under 223 nm excitation.Decay time measurements of the ^(4)G_(5/2)→^(6)H_(7/2) luminescence transition indicate that decay time of nano-sized powder is significantly shorter than bulk material one.
基金financially supported by (i) Suranaree University of Technology,(ii) Thailand Science Research and Innovation,and (iii) National Science,Research and Innovation Fund(project codes 90464 and 160363)。
文摘The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.
基金Funded by the National Natural Science Foundation of China(No.10874075)the Key Program of Hubei Province Education Committee(No. D20082203)
文摘Sol-gel process was adopted to prepare BiFeO3 films.BiFeO3 films were deposited on LaNiO3 coated Si(100) substrates annealed at 500 and 550 ℃,respectively.The X-ray diffraction results reveal that BiFeO3 film has a rhombohedrally distorted perovskite structure with space group R3c.The film annealed at 500 ℃ has larger remnant polarization(Pr) of 35.3 μC/cm2.For the film annealed at 550 ℃,smaller remnant polarization of Pr=4.8 μC/cm^2 is observed for its low breakdown electric field.Lower leakage conduction is observed in the film annealed at 500 ℃ at low applied field.
基金supported by the 973 Research Project of China (6134502)
文摘Nanocrystal SmBO3 powders were synthesized by nitrate-citrate sol-gel combustion method. The phase evolution, morphologies and absorbency of the synthesized powders were characterized by X-ray diffraction (XRD), Field emission scanning electronic microscope (FESEM), Fourier transform infrared spectroscopy (FFIR) and UV-3101PC spectrophotometer (UVPC), respectively. XRD and FESEM results showed that pure SmBO3 phase was obtained at 750 ℃, with an average original particle size of about 100 nm. FTIR showed that there were apparently concentrated absorbent peaks between 500 and 1400 cm^-1. Moreover, the reflectivity of the powders apparently decreased at the wavelength between 1.05 and 1.15 μm. Therefore, SmBO3 might be a kind of absorbent material for infrared laser.
基金the Natural Science Foundation of Hubei Province (Grant Nos. 2003ABA061, 2004ABA082)
文摘The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively.