The rock salt oxide Li2MgTiO4: Type I dielectric and ionic conductor

The exploration of the Li–Ti–Mg–O system, using both sol–gel technique and solid state reaction method, allowed a new phase, Li₂MgTiO₄, with disordered rock salt structure (a = 4.159 Å) to be synthesized. The latter is shown to be a good type I dielectric material, with a relative constant of 15 at high frequency and low dielectric loss (tanδ < 10⁻³) over the temperature range −60 to 160 °C. It is also observed that the sintering temperature of this phase is strongly lowered by adopting the sol–gel technique compared to solid state reaction (1150 °C instead of 1300 °C). Finally we show that this phase exhibits cationic conductivity above 400 °C (σ_600 °C = 9 × 10⁻⁵ S cm⁻¹).     

快离子导体陶瓷的制备与应用

综述了快离子导体陶瓷的制备方法及应用领域 ,并展望了快离子导体的发展前景。     

Preparation, characterization and conductivity studies of AgI-Ag2O-(TeO2 + P2O5) fast ionic conducting glasses

Silverphosphotellurate (SPT) quaternary fast ionic conducting (FIC) glasses of compositions AgI-Ag₂O-[(1 – x)P₂O₅ + xTeO₂], x = 0.0 to 1.0 in steps of 0.1, were prepared by melt quenching. All SPT compounds were characterized by X-ray diffraction and the amorphous nature of the samples was confirmed. The structure of all compositions was examined by Fourier Transform Infrared Spectroscopy. The glass transition temperature (T _g) was determined for all SPT samples, using differential scanning calorimetry. Complex impedance measurements were made on all glasses in the frequency range 40 Hz to 100 kHz. Impedance data were analyzed using Boukamp equivalent circuit software and the bulk conductivity was obtained. The highest conductivity ( = 1.59*10^–2 S/cm) was shown by the composition 60%AgI – 26.67%Ag₂O – 13.33% (0.3P₂O₅ + 0.7TeO₂).     

Thermoelectric power of superionic conductor Ag7I4VO4

Thermoelectric power studies on Ag₇I₄VO₄. superionic conductor have been carried out in the temperature range 25 to 60°C. Thermo-electric power is found to vary linearly with the inverse of the absolute temperature, and can be expressed by the equation −θ = [(0.182 × 10³/T) + 0.276] mV/K. The heat of transport is nearly equal to the activation energy of Ag⁺ ion migration calculated from the conductivity plots indicating that the material has an average structure.     

Bi2O3-Y2O3体系中纳米δ-Bi2O3相的生成规律研究

以分析纯的Bi(NO3)3·5H2O和Y (NO3)3*6H2O作为原料,经反向滴定法化学共沉淀、干燥和430℃焙烧后获得(75mol%Bi2O3+25mol%Y2O3)纳米复合粉体,粉体平均粒度30nm以下;通过常压反应烧结工艺制备了纳米Bi2O3-Y2O3快离子导体,对烧结过程中高导电相(纳米δ-Bi2O3)的形成规律研究结果表明烧结初期以固溶反应为主,后期以晶粒长大为主,晶粒生长规律符合(D-D0)2=K·t抛物线方程;用模式识别技术对δ-Bi2O3相生成的工艺条件进行了优化.     

(PEG) x NH4ClO4: a new polymeric fast proton conductor

A new polymer electrolyte (PEG) _x NH₄ClO₄(x = 5, 10, 15, 20) has been prepared that shows protonic conduction. The room temperature conductivities are of the order of 10⁻⁷S/cm, and increase with decrease in salt concentration. NMR line width studies indicate fairly low glass transition temperatures of the polymer salt complexes. Paper presented at the poster session of MRSI AGM VI. Kharagpur, 1995     

New fast lithium ionic conductor in the Li3NLiILiOH system

The electrical properties of Li₃NLiILiOH (1:2:x molar ratio) compounds are investigated. These quasi-ternary compounds have a cubic crystal structure similar to Li₅NI₂. The Li₃NLiILiOH (1:2:0.77) compound has a conductivity of 0.95 × 10_?1 (S/m at 25°C with an activation enthalpy of 24.6 (kJ/mol). All the compounds investigated are predominantly ionic conductors. The electronic transference number is smaller than 10^?5 and the decomposition voltage of these compounds is about 1.6V at 25°C.     

聚离子液体型聚合物电解质的制备及表征

以N-乙烯基咪唑、溴乙酸甲酯和二（三氟甲基磺酰亚胺）锂（LiTFSI）为原料,采用溶液聚合法制备了聚（1-乙烯基-3-乙酸甲酯基咪唑二（三氟甲基磺酰亚胺））（PMVIm-TFSI）。将其与LiTFSI和聚（甲基丙烯酸甲酯-醋酸乙烯酯）（P（MMA-VAc））共混制得了不同质量比的聚合物电解质。核磁共振（1 HNMR）、红外光谱（FT-IR）、示差扫描量热计（DSC）、热重分析（TGA）、X射线衍射（XRD）、扫描电镜（SEM）、交流阻抗（AC impedance）等对电解质的测试结果表明,PMVIm-TFSI掺杂到P（MMA-VAc）和LiTFSI组成的电解质中后其电导率得到了极大的改善,30℃下最高可达4.71×10-4S/cm,同时热稳定性也得到了极大的提高。此外,该共混电解质（透过率≥90%）还可以运用到电致变色器件（ECD）导电离子材料中,也显示出了优良的电化学性能。     

纳米Li4Ti5O12/C复合材料的制备与性能

基于煅烧温度对Li4 Ti5O12粒径与反应性的影响,采用两步固相反应制备了纳米Li4 Ti5 O12/C复合材料,并采用XRD、SEM、TG/DTA、电化学阻抗谱(EIS)及充放电测试进行了表征.结果显示,无定形TiO2和Li2 CO3原料于600℃反应生成Li2TiO3和金红石TiO2复合物,晶粒基本无生长;高于700℃煅烧,复合物转化为Li4 Ti5 O12,但晶粒生长增速.在原料中掺入蔗糖于800℃一步固相反应制备Li4 Ti5O12/C复合材料,可显著抑制晶粒生长,但产物中含有金红石TiO2杂相,电化学性能不佳.采用两步固相反应,原料于600℃预热处理得到Li2TiO3/TiO2复合物,然后掺入蔗糖于800℃高温煅烧,可制得粒径约100～200nm的纯相Li4 Ti5O12/C复合材料,0.2C放电容量达167.3mAh/g,1C放电容量达163.1mAh/g,1C循环30周后容量保持率达96％.     

Preparation and characterization of K-substituted NaCa4Nb5O17 microwave dielectric ceramics

The effect of K substitution for Na on the phase, microstructure and microwave dielectric properties of the Na_1?x K _x Ca₄Nb₅O₁₇ (x = 0–1) composition series was investigated. The compositions with x = 0, 0.5 and 1 formed single-phase Na_1?x K _x Ca₄Nb₅O₁₇ ceramics within the detection limit of the in-house XRD facility when sintered at 1,200–1,300 °C. At x = 0.25 and 0.75, the major Na_1?x K _x Ca₄Nb₅O₁₇ phase formed but along with a secondary CaNb₂O₆ phase. Relative permittivity (ε _r ) and temperature coefficient of resonant frequency (τ_f) increased from 45 to 51 and ?120 to +473 ppm/ °C respectively while the quality factor (Q × f _o ) decreased from 13,838 to 2,374 GHz with an increase in x from 0 to 1. Optimum microwave dielectric properties (i.e. ε _r  = 47, Q × f _o  = 5,047 GHz and τ_f = ? 23 ppm/ °C) were achieved for the x = 0.5 (i.e. Na_0.5K_0.5Ca₄Nb₅O₁₇) composition. Further investigations are required to improve the density and hence microwave dielectric properties of Na_1?x K _x Ca₄Nb₅O₁₇ ceramics.     

纳米氟硼酸钾粉末的制备及表征

探讨了高能球磨法制备纳米KBF4粉末的工艺过程及影响因素.通过选择合适的球磨工艺及表面活性剂,以普通KBF4粉末为原料成功制备出粉末的粒度均径为81.2nm、比表面积为28.26m2/g的纳米级KBF4粉末.分别采用BET比表面积测试法、X射线小角度散射法(SAXS)及扫描电镜对纳米KBF4粉末进行了表征.     

Preparation and characterization of AlVO4 compound

AlVO₄ is a relatively new sensor material derived from V₂O₅/Al₂O₃ mixtures to selectively detect NO and NO₂ gases. Previous studies carried out in order to determine its structural, absorptive and sensory properties indicate that the AlVO₄ is not the only single phase. This work deals with the synthesis of the compound by the ceramic and the nitrate decomposition methods, and by the sol gel route. The Rietveld refinement of the compound was carried out in order to determine its crystal structure. Single phase of AlVO₄ was successfully obtained via the nitrate decomposition and the sol gel methods. Thereafter, films prepared by the sol gel route were deposited on alumina and Si/SiO₂/Pt substrates and characterized by SEM and X-ray diffraction. The electric characterization of the AlVO₄ on alumina substrate film is also presented.     

Preparation and characterization of ionic liquid intercalation compounds into layered zirconium phosphates

In this work, immobilizing a series of ionic liquids (ILs) 1-alkyl-3-methylimidazolium chloride [C _n mim]Cl (n = 2, 4, 6, 8) on the layered zirconium phosphates were investigated. [C₄mim]Cl was used to explore in detail the factors affecting intercalation. By comparing several starting materials including α-zirconium phosphate (α-ZrP), γ-zirconium phosphate (γ-ZrP) and the corresponding alkylamine preintercalated composites, it was found that the α-ZrP · 2BA (i.e., preintercalated BA were arranged in a bilayer mode at the galleries of α-ZrP) was a suitable host for intercalating ILs. Intercalation was verified with X-ray diffraction (XRD), Raman, UV–Vis and other instrumental approaches. pH effect on immobilization was investigated. Other ionic liquids including [C _n mim]Cl (n = 2, 6, 8) intercalation compounds were prepared. Based on XRD data, the interlayer distances of the studied intercalation compounds were similar, suggesting that the ionic liquids were arranged in an approximately planar manner, as confirmed by molecular modeling.     

ZSM—5沸石膜的合成与表征

叙述了沸石膜的发展与应用,综述了 Ｚ Ｓ Ｍ － ５ 沸石膜的合成、修饰与表征方法．制备膜最常用的方法为水热法在载体上直接就地合成．气相化学沉积法（ Ｃ Ｖ Ｄ） 、溶胶－ 凝胶法（ｓｏｌ － ｇｅｌ） 以及合成后积炭等方法被用来对膜的缺陷进行修饰．膜的表征手段为 Ｘ Ｒ Ｄ、 Ｓ Ｅ Ｍ、气体渗透等     

Preparation and characterization of zirconia and mixed zirconia/titania in ionic liquids

Zirconia and mixed zirconia/titania were synthesized in two different ionic liquids, namely, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP]TFSA) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide ([EMIm]TFSA) using sol–gel methods. The synthesized oxides were characterized by means of X-ray diffraction, scanning electron microscopy with energy dispersive X-ray (SEM-EDX)), thermogravimetric and differential thermal analyses (TGA–DTA). The results show that the as-synthesized ZrO₂ powders obtained either in [BMP]TFSA or in [EMIm]TFSA show amorphous behaviour, and calcination at 500 °C yields t-ZrO₂ which is subject to further phase transformation to m-ZrO₂ at 1000 °C. The type of the ionic liquid influences the morphology of the synthesized zirconia as the sample obtained from [BMP]TFSA showed a porous morphology with very fine particles in the nanometer regime, whereas micro-rods were obtained from [EMIm]TFSA. ZrO₂-TiO₂ nanorods with an average diameter of about 100 nm were synthesized in [EMIm]TFSA. The presence of zirconia in the mixed oxides stabilizes the anatase phase and elevates the temperature at which the phase transformation to rutile occurs.     

Preparation and structural properties of the solid state ionic conductor CuTi2 (PO4)3

The solid state ionic conductor CuTi₂(PO₄)₃ belonging to the Nasicon family has been synthesized; its lattice parameters have been obtained from X-ray diffraction patterns by comparison with isostructural NaTi₂(PO₄)₃. The characterization of this light brown solid has been completed by IR and UV-visible spectroscopies. Reverse ion exchange between Cu and Na has been shown to occur in a molten salt bath. These properties are discussed through the main structural features of the M^IM′^IV₂(PO₄)₃ family.     

锂离子电池负极材料Li4Ti5O12的合成及电化学性能

采用高温固相反应法制备尖晶石相Li4Ti5O12负极材料.初步研究了反应温度和反应时间对Li4Ti5O12电化学性能的影响.XRD衍射未观测到TiO2残余存在;电化学测试显示,1.2～2.5V恒流充放电,其可逆容量达158.3mAh/g,首次库仑效率为95.2%;循环20周其容量衰减率仅为3.1%.     

Preparation and characterization of V2O5 macro-plates

V₂O₅ macro-plates have been prepared using water/ethanol media. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The as-prepared V₂O₅ plates appear to be an orthorhombic structure, and they seem to be composed of strip-like V₂O₅ nanocrystals which appear to be parallel or perpendicular to each other. The band gap of the V₂O₅ macro-plates calculated from the optical absorption edge is about 3.4 eV, showing a strong blue shift compared to bulk V₂O₅. It is also found that the final shape of the V₂O₅ macro-plates strongly depends on the reaction conditions. The possible formation mechanism of the V₂O₅ macro-plates is discussed.     

Preparation and characterization of bulk ZnGa2O4

High-quality bulk ZnGa₂O₄ has been synthesized from equimolar mixtures of ZnO and Ga₂O₃ by the conventional solid-state method. For the first time, the sample has been characterized in detail to confirm the formation of pure single phase of spinel ZnGa₂O₄. The formation of ZnGa₂O₄ has been confirmed by sintering the mixtures of ZnO and Ga₂O₃ at different temperatures, ranging from 900–1200 °C. It is observed that the single phase of ZnGa₂O₄ has been formed at and above 1000 °C sintering temperature for 24 h. The crystallinity and phase formation of this single phase has been confirmed by X-ray diffraction. X-ray photoelectron spectroscopic studies have been carried out for bulk ZnGa₂O₄ sintered at 1000 °C for 24 h which showed 14% Zn, 28% Ga and 58% O, indicating stoichiometric ZnGa₂O₄. A new parameter, the energetic separation between the Zn 2p_3/2 and Ga 2p_3/2 peaks, has been used as a sensitive tool to distinguish between a complete formation of ZnGa₂O₄ compound and a mixture of ZnO and Ga₂O₃ powders. Surface morphology studies by scanning electron microscopy reveal that the formation of ZnGa₂O₄ takes place in mosaic rod-like structure. The purity of the compound has also been checked by the energy dispersive X-ray method, indicating the absence of foreign ions and the ratio of zinc to gallium has been calculated and found to be 1 : 2, indicating stoichiometric ZnGa₂O₄.