纳米粉体(CeO_2)_(0.9-x)(GdO_(1.5))_x(Sm_2O_3)_(0.1)的溶胶-凝胶低温燃烧合成

采用溶胶 -凝胶法与低温燃烧法相结合 ,合成了 (CeO2 ) 0 .9-x(GdO1 .5 ) x(Sm2 O3) 0 .1 系列粉体 .结果表明 :由硝酸盐与柠檬酸混合形成的凝胶 ,可在较低温度 (2 0 0～ 3 0 0℃ )点火并燃烧 ,其火焰温度达 90 0℃以上 .经TEM ,XRD测试 ,燃烧后即直接形成了粒径为 2 0～ 3 0nm ,具有萤石结构的单相粉体 ,由该粉体制备的固体电解质在中温下电导率为 5 .8× 10 - 2 S/cm ,组装的单个H2 -O2 燃料电池最大功率密度达 70mW /cm     

共沉淀和低温燃烧法制备Sr0.9Ce0.9V0.1O3-δ陶瓷粉及性能

分别采用基于Pechini法的溶胶低温燃烧法和共沉淀法制备了Sr0.9Ce0.9Y0.1O3-δ(SCY)超细陶瓷粉.应用X射线衍射、扫描电镜、能量散射谱和激光粒度分析仪对陶瓷粉体的结构和组成进行了表征,并研究了两种方法制备的粉体的烧结性能.结果表明用溶胶低温燃烧法制备的SCY粉体为近似球形、粒径小于50nm,粒度分布范围窄,在1250℃烧结致密;用共沉淀法制备的粉体具有钙钛矿结构,粒径小于0.25μm、粒度分布窄,在1300℃烧结致密.此外,SCY致密膜具有一定的透氢作用,850℃氢渗速率在2×10-3 mL·cm-2·min-1左右.     

自蔓延低温燃烧-溶胶凝胶合成Ce0.8Sm0.2O1.9及烧结性能

用甘氨酸作还原剂、硝酸盐作氧化剂,采用溶胶-凝胶与自蔓延低温燃烧相结合的方法制备了超细Ce_0.8Sm_0.2O_1.9 (SDC)固溶体,对所合成的粉体分别采用XRD、SEM和BET法进行了表征。结果表明,600℃焙烧产物是具有较高相纯度的单一立方相萤石型结构固溶体,根据XRD估算晶粒度为13～30 nm。甘氨酸与金属硝酸盐(G/N)摩尔比对粉体的微观形貌和烧结性能有很大影响, 当G/N相似文献   

溶胶-凝胶法制备Li-β-Al2O3纳米粉体

以硝酸锂、硝酸铝和碳酸氢铵为原料,采用溶胶-凝胶法制备了Li-β-Al2O3纳米粉体。研究了pH值、热处理温度和锂铝物质的量比[n（Li）/n（Al）]对制备Li-β-Al2O3纳米粉体的影响。用X射线衍射仪（XRD）、场发射扫描电镜（FE-SEM）和自动电位粒度仪对制备的粉体进行了表征。结果表明,当n（Li）/n（Al）=1∶5（为化学计量比时）,pH值在3.6左右时,可得到稳定透明的凝胶,经1000℃热处理后,产物为纯相的Li-β-Al2O3,FE-SEM结果表明粉体的粒度在100nm以内。     

共沉淀和低温燃烧法制备Sr0.9Ce0.9Y0.1O3-δ陶瓷粉及性能

分别采用基于Pechini法的溶胶低温燃烧法和共沉淀法制备了Sr_(0.9)Ce_(0.9)Y_(0.1)O_(3-δ)(SCY)超细陶瓷粉。应用X射线衍射、扫描电镜、能量散射谱和激光粒度分析仪对陶瓷粉体的结构和组成进行了表征,并研究了两种方法制备的粉体的烧结性能。结果表明:用溶胶低温燃烧法制备的SCY粉体为近似球形、粒径小于50nm,粒度分布范围窄,在1250℃烧结致密;用共沉淀法制备的粉体具有钙钛矿结构,粒径小于0.25μm、粒度分布窄,在1300℃烧结致密。此外,SCY致密膜具有一定的透氢作用,850℃氢渗速率在2×10-3mL.cm-2.min-1左右。     

固体电解质BaPr_（0.9）Y_（0.1）O_3粉体的制备

固体电解质在燃料电池,气体传感器,气体分离和气体制备及化学反应器等方面均有应用的可能,因此,在能源,环保,化学工业,电子工业和航空航天工业等领域均有着十分广阔的应用前景,本文主要采用溶胶燃烧法和热解法制备钙钛矿型氧化物质子导体BaPr0.9Y0.1O3陶瓷粉体。考察溶液组成、燃烧温度、煅烧温度、热解温度等对粉体物相组成、粉体粒度以及粒度分布的影响。寻找合适的制备BaPr0.9Y0.1O3粉体的方法。解决粉体组成不均匀、粒度分布范围宽以及烧结温度高的问题。     

溶胶-凝胶低温燃烧合成法制备Sm0.15Gd0.05Ce0.8O1.9纳米粉体

采用溶胶-凝胶与低温自蔓延燃烧相结合的方法合成了纳米级超细Sm0.15Gd0.05Ce0.8O1．9粉体，选用的合成体系有：柠檬酸-硝酸盐，甘氨酸-硝酸盐，EDTA络合-硝酸盐等方法。对所合成粉体进行了XRD，TEM及激光Raman光谱仪(laser Raman spectroscope，LRS)检测，研究了不同方法制备的粉体的结构及晶相。结果表明：XRD和LRS相结合能较好地表征固溶体的结构和纯度，几种方法合成的粉体为纯度高的掺杂氧化铈固溶体，晶粒尺寸较均匀，但分散性差。影响最终合成的超细粉体粒径的因素有：有机络合剂的种类、性质，有机络合剂与总金属阳离子比例及形成掺杂固溶体所需的温度。     

纳米α-Al_2O_3粉体的低温燃烧合成与表征

以硝酸铝-尿素为反应体系,采用低温燃烧合成法制备了α-Al2O3粉体。通过X射线衍射、扫描电镜、透射电镜和能谱分析等检测,对产物进行了表征。结果表明,硝酸铝和尿素的摩尔比为1∶2.5,加热至450℃可发生燃烧合成反应,此温度下保温煅烧5min后可得到纳米α-Al2O3粉体,反应产物颗粒边缘光滑,粒度分布均匀,呈白色。XRD结果表明有机物已完全分解,经XRD计算、TEM及纳米粒子分析测定,晶粒尺寸在20～60nm之间。     

溶胶-凝胶燃烧法合成Cr~(3+):Al_2O_3纳米粉体

采用溶胶-凝胶燃烧法合成出Cr3+:Al2O3纳米粉体.将所制成的干凝胶加热至约500℃使之发生燃烧反应,再将燃烧产物在不同的温度下进行锻烧.利用热重-差热分析、X射线衍射(X-ray diffraction,XRD)、透射电子显微镜(transmission electron mictoscope,TEM)等对干凝胶及煅烧粉体进行表征,测试了纳米粉体的发光性能.研究了合成条件对粉体分散性、发光性能的影响.XRD和TEM分析表明:在1000℃煅烧1h后,粉体为α-Al2O3结构的单相氧化物粉体,颗粒大小为20～35nm.在制备溶胶时添加聚乙二酵可提高粉体的分散性.光谱分析表明:Cr3+:Al2O3纳米粉体的激发峰位于404nm和540nm,发射峰值位于692nm和668nm.     

纳米Ce0.9Cu0.1O2-δ固溶体的制备、表征和CO低温氧化性能

采用改进的柠檬酸溶胶-凝胶法(即前驱体先在N2气氛下高温预处理)制备了高比表面积纳米Ce0.9Cu0.1O2-δ固溶体。采用XRD、TEM和Raman等对催化剂进行表征,并考察了它们的低温CO氧化性能。研究结果表明,改进的柠檬酸溶胶-凝胶法可以制得晶相比较完整的Ce0.9Cu0.1O2-δ固溶体,晶粒小于10 nm,明显小于常规方法制得的样品。随着样品焙烧温度的提高,表征氧缺位的600 cm-1左右Raman峰的位置向高波数方向迁移。采用改进方法制得的Ce0.9Cu0.1O2-δ固溶体具有更高的CO氧化活性,其原因归结为晶粒的减小,容易形成氧缺位和表面高分散CuO的增加,从而促进了CO的氧化。     

Samarium Coordinated Polymer: Structural, Vibrational and Thermal Studies of [Sm2(C3H2O4)3(H2O)6]n

The title compound, [Sm₂(C₃H₂O₄)₃(H₂O)₆]_, was investigated by X-ray diffraction. It crystallizes in the monoclinic space group C2/c with cell parameters a = 17.1650(8) ?, b = 12.3010(5) ?, c = 11.1420(4) ?, β = 127.5161(10)°, Z = 4 and V = 1866.04(14) ?³. The Sm atom lies on a two-fold axis and has nine-coordination with six oxygen atoms from carboxylate groups and three water molecules. The compound forms a layer-type polymeric structure. The layers are formed by samarium and one independent malonate group to give a three-dimensional framework. The extensive network of hydrogen bonds and bridge bonds observed in this structure enhances the structural stability. The thermal dehydration of the compound was investigated by thermogravimetric analysis.     

Synthesis, structure and photoluminescence of a novel palladium(I) compound: [Pd3(μ3-Cl)2(dppp)3][Pd2(μ2-Cl)3(PPh3)2](PPh3)2

Pd(PPh₃)₂Cl₂ reacts with PdCl₂ and 1,3-bis(diphenylphosphine)propane (dppp) in ethanol–DMF–pyridine mixed solvent to yield a novel palladium(I) compound [Pd₃(μ₃-Cl)₂(dppp)₃][Pd₂(μ₂-Cl)₃(PPh₃)₂](PPh₃)₂. It features an isolated structure based on [Pd₃(μ₃-Cl)₂(dppp)₃]⁺ cations having triangulo-palladium clusters and [Pd₂(μ₂-Cl)₃(PPh₃)₂]⁻ anions in which the coordination environment of palladium is an unusual tetrahedral geometry. Its photoluminescence is measured.     

Structural,electrical and ferroelectric characteristics of Bi(Fe0.9La 0.1)O3

Nowadays, much attention is paid for the development of lead-free complex or mixed metal oxides, which can be utilized for multi-functional devices. This communication provides the information on synthesis (by mixed oxide route) and physical properties (structural, electrical and ferroelectric) of the polycrystalline sample of Bi(Fe_0.9La_0.1)O₃ Analysis of the phase formation and basic crystal data of the material using X-ray diffraction (XRD) technique shows an orthorhombic symmetry with well-defined cell parameters. It has been shown that a small amount (10%) of La substitution at the Fe site of BiFeO₃ suppresses the impurity phase usually observed during phase formation of BiFeO₃. The average crystallite size, calculated through applying Scherrer's technique, was found to be 68?nm. For the study of surface morphology (grain size and distribution) of the compound, the scanning electron microscope (SEM) was used. The grains of different dimension were found homogeneously distributed at the entire surface of the sample. The La substitution strongly affects the capacitive (dielectric) and resistive (electrical) characteristics of bismuth ferrite in a wide range of frequency and temperature. The contributions of grains and grain boundaries in the capacitive as well as in the resistive properties of the material at different temperatures and frequencies were studied by means of the impedance spectroscopy technique. This study has provided numerous useful and interesting data which may find potential industrial applications.     

Manganese effect on the relaxation behaviors of the space charge polarization in Pb(Fe2/3W1/3)0.9Ti0.1O3 ceramics

The effects of manganese on the space charge polarization in 0.9Pb(Fe_2/3W_1/3)O₃-0.1PbTiO₃ (0.9PFW-0.1PT) ceramics are discussed using the Debye theory and the Arrhenius law. The static dipole moment of the space charge polarization is decreased by the MnO additives. The values of the Debye relaxation time τ₀ and the activation energy E_τ of the space charge polarization are similar at any temperature range before adding MnO. These values are changed after adding MnO and are obviously changed only at the lower temperature range. According to these results, it is suggested that the space charge polarizations are induced due to the charge imbalance in the micropolarization region and the conductive carriers. The charge imbalance and the conductive carriers are reduced by adding MnO additives since the compositional fluctuation is restrained and the electronic compensation is induced.     

Preparation and Properties of （Na0.50＋xK0.50-2xLix）Nb0.9Ta0.1O3 Lead-Free Piezoelectric Ceramics by Sol-Gel Method

采用溶胶–凝胶法制备Li＋取代（K0.5Na0.5）＋及Ta5＋取代Nb5＋的（K0.5Na0.5）NbO3陶瓷粉体,采用无压烧结工艺制备（Na0.50＋xK0.50–2xLix）Nb0.9Ta0.1O3（x=0,0.02,0.04）陶瓷样品。研究了前驱体煅烧温度对陶瓷粉体物相组成的影响。分析了不同Li＋掺杂量对样品物相组成、微观结构、体积密度及电学性能的影响。结果表明：前驱体的最佳煅烧温度为600℃,通过透射电子显微镜分析陶瓷粉体的粒径为49nm;不同Li＋掺杂量制备的（Na0.50＋xK0.50–2xLix）Nb0.9Ta0.1O3陶瓷样品均为正交相钙钛矿结构;随着Li＋掺杂量的增加,（Na0.50＋xK0.50–2xLix）Nb0.9Ta0.1O3陶瓷的体积密度先增大后减小,介电常数逐渐升高,压电常数先降低再升高,剩余极化强度逐渐升高。Li＋掺杂量x为0.04时样品的压电常数（d33=94pC/N）、相对介电常数（εr=684.33）及剩余极化强度（Pr=98.27μC/cm2）较好。     

Hydrothermal synthesis of LiNi0.9Co0.1O2 cathode materials

Ultrafine powders of LiNi_0.9Co_0.1O₂ were prepared under mild hydrothermal conditions. The product was characterized by XRD, TEM and EDS tests, which indicated that the obtained products were pure and well-crystallized LiNi_0.9Co_0.1O₂. The ICP-AES results indicated the products were lithium-deficient compounds. The addition of KOH hardly effected the crystallinity of the product but gave larger crystals.     

A study of CaO (Fe2O3)1−x (Al2O3)x system

The members of the ferrite series CF_1?1A_x and with O ? × ? 0.8 have been studied by x-ray diffraction and Mössbauer spectroscopic techniques. The observed Mössbauer parameters are explained in the light of the following model, which is supported by the x-ray data. For non-zero x, the two phases CF and CA co-exist such that Al and Fe are distributed in these, respectively. With increase in x, the CF phase decreases and the CA phase increases.     

Synthesis of LiNi0.9Co0.1O2 from Li2CO3, NiO or NiCO3, and CoCO3 or Co3O4 and their electrochemical properties

Cathode active materials with a composition of LiNi_0.9Co_0.1O₂ were synthesized by a solid-state reaction method at 850 °C using Li₂CO₃, NiO or NiCO₃, and CoCO₃ or Co₃O₄, as the sources of Li, Ni, and Co, respectively. Electrochemical properties, structure, and microstructure of the synthesized LiNi_0.9Co_0.1O₂ samples were analyzed. The curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂ for the first charge–discharge and the intercalated and deintercalated Li quantity Δx were studied. The destruction of unstable 3b sites and phase transitions were discussed from the first and second charge–discharge curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂. The LiNi_0.9Co_0.1O₂ sample synthesized from Li₂CO₃, NiO, and Co₃O₄ had the largest first discharge capacity (151 mA h/g), with a discharge capacity deterioration rate of −0.8 mA h/g/cycle (that is, a discharge capacity increasing 0.8 mA h/g per cycle).     

Co2O3 substitution effects on the structure and microwave dielectric properties of low-firing (Zn0.9Mg0.1)TiO3 ceramics

Low-firing (Zn_0.9Mg_0.1)_1?xCo_xTiO₃ (x = 0.02–0.10) (ZMC_xT) microwave dielectric ceramics with high temperature stability were synthesized via conventional solid-state reaction. The influences of Co₂O₃ substitution on the phase composition, microstructure and microwave dielectric properties of ZMC_xT ceramics were discussed. Rietveld refinement results show the coexistence of ZnTiO₃ and ZnB₂O₄ phases at x = 0.02–0.10. (Zn_0.9Mg_0.1)_1?xCo_xTiO₃ ceramic with x = 0.06 (ZMC_0.06T) obtains the best combination microwave dielectric properties of: ε_r = 21.58, Q × f = 53,948 GHz, τ_f = ? 54.38 ppm/°C. For expanding its application in LTCC field, 3 wt% ZnO-B₂O₃-SiO₂ (ZBS) and 9 wt% TiO₂ was added into ZMC_0.06T ceramic, great microwave dielectric properties were achieved at 900 °C for 4 h: ε_r = 26.03, Q × f = 34,830 GHz, τ_f = ? 4 ppm/°C, making the composite ceramic a promising candidate for LTCC industry.     

Electrical properties of (Bi2O3)0.75(RE2O3)0.25 ceramics (RE=Dy, Y, Ho, Er and Yb)

Five kinds of rare earth stabilized bismuth oxide ceramics, (Bi₂O₃)_0.75(RE₂O₃)_0.25 (RE=Dy, Y, Ho, Er and Yb), were synthesized by sintering a mixture of Bi₂O₃ and RE₂O₃ at 900–1100 °C and their electrical properties were investigated. The bulk density and the lattice constant linearly increased with an increase in the atomic weight of RE and the ionic radius of RE³⁺, respectively. The electrical conductivity at 300 °C slightly increased with the increasing ionic radius of RE³⁺, while at 500 and 700 °C, it was constant regardless of the ionic radius of RE³⁺. The migration activation energy and the association activation energy showed a maximum value and a minimum value at RE=Er, respectively.