Nanocomposite films of V<Subscript>2</Subscript>O<Subscript>5</Subscript>−MoO<Subscript>3</Subscript> xerogel with poly ethylene oxide intercalation

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)     

Synthesis and characterization of (PEO)<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>−(V<Subscript>0.85</Subscript>Mo<Subscript>0.15</Subscript>)<Subscript>2</Subscript>O<Subscript>5</Subscript> nanocomposite films

(PEO) _x −(V_0.85Mo_0.15)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 (V_0.85Mo_0.15)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 (V_0.85Mo_0.15)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 (V_0.85Mo_0.15)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)     

Lithium Insertion in Poly(ethylene oxide)/MoO_3 Xerogel Nanocomposite Films

1　ＩｎｔｒｏｄｕｃｔｉｏｎＧｒｅａｔｅｆｆｏｒｔｓｈａｖｅｂｅｅｎｍａｄｅｉｎｒｅｃｅｎｔｙｅａｒｓｔｏｄｅ ｖｅｌｏｐｎｅｗｉｎｔｅｒｃａｌａｔｉｏｎｈｏｓｔ ｇｕｅｓｔｃｏｍｐｏｕｎｄｓｗｉｔｈｎｏｖｅｌｐｒｏｐｅｒｔｉｅｓａｓｍａｔｅｒｉａｌｓｆｏｒｅｌｅｃｔｒｏｃｈｒｏｍｉｃｄｅｖｉｃｅｓａｎｄｓｅｃ ｏｎｄａｒｙｌｉｔｈｉｕｍｂａｔｔｅｒｉｅｓ[1- 4] .ＣｏｍｐｏｕｎｄｓｂａｓｅｄｏｎＭｏＯ3 ｈａｖｅａｔｔｒａｃｔｅｄｍｏｒｅａｔｔｅｎｔｉｏｎｄｕｅｔｏｔｈｅｉｒｄｅｓｉｒａｂｌｅｃｈａｒ…     

Laminated all-solid state NiO/WO3 complementary electrochromic device

Based on the previous studies on the rf reactive sputtered nickel oxide film with nanostructure and its electrochronism, i.e. electrochromic effect of the films is attributed to the reversible change of the non-stoichiometry in the nanocrystalline grain boundaries and interfaces due to the injection and ejection of Li⁺ ions, a prototype of all-solid-state NiO/WO₃ complementary electrochromic device using Li _x TaO _y thin film as inorganic electrolyte was designed and prepared. The results indicate that the solar reflectance of the device could be modulated from 0.15 in colored state to 0.60 in bleached state with excellent cyclic reversibility, durability and high response speed (less than 0.3 s from colored state to bleached state). Project supported by the National Natural Science Foundation of China and the National Climbing Programme A: Nano-structured Materials Sciences.     

Preparation of Poly （ethylene oxide） （PEO） Modified Tungsten Oxide Hybrid Films via Sol-Gel Processing

Poly ( ethylene axide ) ( PEO ) modified WO3 thin films were prepared on glass substrates with special temperature. The sol-gel transition proess was #westigated by using DTA - TG , SEM and XRD. The elec-trochemical characteristic of the films was studied by cyclic voltmmetry measurement. The results show that PEO has heavy effects on the crystallization of W03 during structure evolution because of the interaction between PEO and WO3. It increases the crystallization temperature of the gels and thus improves the electrochemical properties and cyclic life of WO3 film as electrochromic materials.     

Synthesis and Characterization of (PEO)_x~-(V_(0.85)Mo_ (0.15)_2O_5 Nanocomposite Films

1　IntroductionSomeinorganiclayeredcompounds ,suchasMoO3 andV2 O5,belongtoarapidlygrowingfieldofcontempo raryresearchinterest,becausetheycanbeintercalatedbyavarietyofalkaliions (Li+ ,Na+ ,etc .) ,atomsorlargermoleculestoformintercalationhost guestcompounds ,whichareexpectedtobepromisingcandidatematerialsforcathodesofsecondaryLibatteriesandelectrochromicdevices[1] .Polymer layeredoxidenanocompositesareat tractingmuchattentionduetotheirspecialstructureaswellassuperiorelectrical,electrochemical…     

Novel preparation and XPS analysis of V<Subscript>2</Subscript>O<Subscript>5</Subscript> xerogel

The V₂O₅ sol was fabricated by ultra-fast quenching. The vanadium with low valence (V⁴⁺) was found in V₂O₅ xerogel films by XPS analysis. The technology of oxygen top-blown was applied to analyze the XPS spectrum difference of V₂O₅ xerogel when the powder of V₂O₅ was melting in air or in oxygen atmosphere. The results show that the different melting atmosphere has certain influences on the chemical valence of V₂O₅ xerogel. ZHU Quan-yao: Born in 1968 Funded by the National Natural Science Foundation of China (No. 50172036, No. 59802009)     

The Mechanism of Sol-Gel Synthesis of Normal Spinel LiMn2O4 with Chelation of Citric Acid

The sol-gel process of citric acid chelating with metal cations for the synthesis of normol spinel LiMn2O4 and the reaction mechanion mechavism were investigated by means of XRD,TG-DTA,and SEM ,the results show that at the beginning lithium citrate and chelate compound of citic acid with manganese ions formed ,and then with heating the esterification and condensation reacions occured between them and glyol ,The products obtained are polymers in which metal cations are distibuted homogeneously on atomic scale that ensur hight reacivity to cations of Li^ and Mn^2 ,Firing the gel grepared by this process ,the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are elinimated and avoided .At 400℃ phase-pure LiMn2O4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained ,The model of chelate coordinated of double -molecule between citric acid and Mn^2 in the gel network is proosed ,It is important for explaining the dispersion state of Mn^2 and the formaiton process of gel by this model.     

Preparation of λ-MnO2 by Column Method and Its Ion-Sieve Property

λ-MnO₂ was prepared by column method from normal spinel LiMn₂O₄ with purity of 99.38%. The influence of LiMn₂O₄ grain size and acidity of leaching solution on the lithium leaching process was studied. The results show that the appropriate range of LiMn₂O₄ grain size was 60–160 meshes and the concentration of leaching solution HCl was 0.1 mol·L⁻¹. The adsorption capacity Q of λ-MnO₂ for lithium increased with the increase of pH and changed markedly at pH 6.0–10.0. It was 3.80mmol/g at pH 12.0 The distribution coefficients K_d of Li⁺ and Na⁺ were 3.406×10⁴ and 2.300 respectively, and the separation coefficient a _Na ^Li was 1.481 ×10⁴ at pH 6.5. As a result, λ-MnO₂ is a high performance ion-sieve material for lithium ion. LEI Jia-heng: Born in 1957. Funded by the National Natural Science Foundation of China (No. 59972027) and the Natural Science Foundation of Hubei Province (No. 2002AB074)).     

Nanocomposite Films of V_2O_5-MoO_3 Xerogel with Poly Ethylene Oxide Intercalation

1　IntroductionItiswell establishedthatsomeinorganiclayeredcompoundssuchasMoO3 ,V2 O5canbeintercalatedbyavarietyofalkaliions (Li+ ,Na+ ,etc .) ,atomsandlargermoleculestoformintercalationhost guestcompounds ,whichareexpectedtobeusedaspotentialcathodicmate rialsinsecondaryLibatteriesandelectrochromicdevice s[1] .Thepolymer layeredoxidenanocompositeshaveat tractedmuchattentionduetotheirspecialstructureaswellassuperiorelectrical,electrochemicalandopticalproperties .Recently ,nanocompositesof (P…     

Preparation of LiFePO4 for lithium ion battery using Fe2P2O7 as precursor

In order to obtain a new precursor for LiFePO4, Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃ using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere. Using the as-prepared Fe2P2O7, Li2CO3 and glucose as raw materials, pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃ in an argon atmosphere. X-ray diffractometry and scanning electron microscopy（SEM） were employed to characterize the as-prepared Fe2P2O7, LiFePO4 and LiFePO4/C. The as-prepared Fe2P2O7 crystallizes in the Cl space group and belongs to β-Fe2P2O7 for crystal phase. The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0 μm. During the Li^＋ ion chemical intercalation, radical P2O7^4- is disrupted into two PO4^3- ions in the presence of O^2-, thus providing a feasible technique to dispose this poor dissolvable pyrophosphate. LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA·h/g, respectively.     

Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> thin films prepared by sulfurizing different multilayer metal precursors

Cu₂ZnSnS₄ (CZTS) thin films were successfully fabricated on glass substrates by sulfurizing Cu-Sn-Zn multilayer precursors, which were deposited by ion beam sputtering and RF magnetron sputtering, respectively. The structural, electrical and optical properties of the prepared films under various processing conditions were investigated in detail. Results showed that the as-deposited CZTS thin films with the precursors by both ion beam sputtering and RF magnetron sputtering have a composition near stoichiometric. The crystallization of the samples, however, has a strong dependence on the atomic percent of constituents of the prepared CZTS films. A single phase stannite-type structure CZTS with a large absorption coefficient of 10₄/cm in the visible range could be obtained after sulfurization at 520°C for 2 h. The samples relative to the RF magnetron sputtering showed a low resistivity of 0.073 Ωcm and band gap energy of about 1.53 eV. The samples relative to the ion beam sputtering exhibited a resistivity of 0.36 Ωcm and the band gap energy is about 1.51 eV. Supported by the National Natural Science Foundation of China (Grant No. 10574106), the Planned Science and Technology Project of Guangdong Province (Grant No.2003C05005) and the Natural Science Fund of Zhanjiang Normal University (Grant No.200801)     

Fabrication and magnetic properties of Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanocomposite permanent magnetic material

Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanometer magnetic material was fabricated through rapid solidification, crystallization and nitridation of Sm-Fe (Ti) alloy. The effect of combination of rapid solidification and Ti alloy addition on the phase formation and microstructure of the Sm-Fe alloy is investigated in this paper. The microstructure of amorphous phase and dual-phase nano-grain crystals before and after crystallization annealing were observed using a high-resolution transmission electron microscope (HREM). The dual-phase nano-grains after annealing were compacted together with a clear interface with the direct exchange-coupling mechanism. Different annealing processes were used to examine the melt-spun alloy. Comparison of the images of SEM showed that annealing at 750℃ for 10 min was most suitable to get homogeneous and nano-grains. No obvious kink was detected in the second quadrant of the hysteresis loop like a single hard magnet, and strong exchange coupling was found between hard magnets and soft magnets.     

Ferroelectric properties of Bi3.4Ho0.6Ti3O12 thin films prepared by sol-gel method

We have prepared the Ho-substituted bismuth titanate (Bi_3.4Ho_0.6Ti₃O₁₂, BHT) thin films on Pt/Ti/SiO₂/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm² and 376.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 310 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×10⁹ switching cycles at 1 MHz frenquency, and the BHT film shows good insulating behavior according to the test of leakage current. Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309)     

THE NANOCOMPOSITE FILM OF POLYMER INTERCALATION IN V_2O_5 XEROGEL

The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V_2O_5 xerogel in sol-gel. The synthesis and state of the films are in vestigated by the XRD, IR, SEM, etc. The results show that V_2O_5 xerogel is a layered structure which arranges in c-direction. The interlayer distance of V_2O_5 xerogel increases remarkably when PEO is intercalated in V_2O_5 xero gel interlayer. PEO has strong interaction with V_2O_5 host. The surface of the films is homogeneous without holes and cracks.     

Effect of Bi content in precursor solutions on microstructure and ferroelectric properties of bismuth cerium titanate thin films

Sol-gel derived bismuth cerium titanate (BCT) thin films with different Bi contents in precursor solutions were deposited on the Pt/Ti/SiO₂/Si substrates. The effect of Bi content in the precursor solutions on the microstructure and ferroelectric properties of the films was investigated. It is found that with Bi content increasing from 90% to 110% of the nominal value in the precursor solutions, the dissipation factor and leakage current density of the BCT films obtained decrease, while the grain sizes, dielectric constant and remanent polarizations (2Pr) increase, and concurrently, a Bi-deficient phase of Bi₂Ti₂O₇ gradually disappears. The film prepared from solution with 110% of the nominal Bi content exhibits pure Bi-layered Aurivillius polycrystalline phase, and the 2Pr value and coercive field value are 67.1 μC/cm² and 299.7 kV/cm, respectively. Their dielectric constant and the dissipation factor are about 172 and 0.033 at 1 kHz, respectively. Moreover, this film shows no polarization fatigue after 4.46×10⁹ switching cycles. Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309)     

Preparation and electrical properties of BaPbO3 thin film

BaPbO3 thin films were deposited on Al2O3 substrates by sol-gel spin-coating and rapid thermal annealing. The microstructure and phase of BaPbO3 thin films were determined by X-ray diffractometry, scanning electrons microscopy and energy dispersive X-ray spectrometry. The influence of annealing temperature and annealing time on sheet resistance of the thin films was investigated. The results show that heat treatment, including annealing temperature and time, causes notable change in molar ratio of Pb to Ba, resulting in the variations of sheet resistance. The variation of electrical properties demonstrates that the surface state of the film changes from two-dimensional behavior to three-dimensional behavior with the increase of film thickness. Crack-free BaPbO3 thin films with grain size of 90 nm can be obtained by a rapid thermal annealing at 700 ℃ for 10 min. And the BaPbO3 films with a thickness of 2.5 μm has a sheet resistance of 35 Ω·-1.     

Effect of Nb on the mechanical properties of Ti/Al2O3 composite

Ti/Al₂O₃ composite with improved mechanical properties was synthesized by the spark plasma sintering. The effect of Nb on the microstructure of the composite was analyzed by TEM, SEM and so on. The experimental results indicate that the bending strength, fracture toughness, micro-hardness and relative density of the composite are 897.29MPa, 17.38MPa·m^1/2, 17.13GPa and 99.24% respectively when adding 1.5vol Nb. The bending strength is improved by reason of forming dislocation ring and transfering fracture mode from integranular to mixture fracture of intergranular and transgranular. The crack propagating is mainly the deflection bridging. It indicates a reduction of crack driving force and an increase in crack growth resistance, which results in toughness enhanced. Funded by the National Natural Science Foundation of China (No. 50232020) and the Natural Science Foundation of Shandong Province (No. 2002F21)     

Synthesis and characterization of a new Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> pillared triple-layered perovskite KSr<Subscript>2</Subscript>Nb<Subscript>3</Subscript>O<Subscript>10</Subscript>

A n-Hexyl NH₃Sr₂Nb₃O₁₀ is obtained by the stepwise ion-exchange reaction, then is dispersed in aqueous solution of trinuclear acetato-hydroxo iron (III) nitrate, [Fe₃(OCOCH₃)₇OH·2H₂O]NO₃, and the interlayer potassium cations of the perovskite niobate are exchanged with the partially hydrolyzed trinuclear acetato complex ions. On heating, the exchanged complex ions are converted into iron oxide pillars which keep the perovskite sheets apart. The product is characterized by XRD, SEM, EDAX and surface area measurement respectively. Zhang Hui: Born in 1970 Funded by the National Natural Science Foundation of China (No. 50002007), Major Program of Ministry of Education (No. 0201) and Open Foundation of State Key Lab of Advanced Tech. for Materials Synthesis and Processing.