热处理温度对TiO2-WO3复合光催化材料储能特性的影响

以离子交换法获得的可溶性钨酸溶液与TiO₂为原料,制备了TiO₂-WO₃复合光催化材料. 用电化学恒电流放电法表征了材料的储能特性,并结合XRD、TEM、BET、UV-Vis等手段,研究了材料中WO₃的晶型和结晶度随热处理温度的变化及其对材料光催化储能效应产生的影响. 在电化学测试中,TiO₂-WO₃复合材料显示了一定的光催化储能特性. 且WO₃的结晶度对材料储能性有一定的影响：WO₃为水合态或结晶度很低时,材料几乎没有光催化储能性;随着结晶度的增强,储能性提高;TiO₂-WO₃的储能性能最高达到0.83×10^-3C·mg^-1; 结晶度过高,储能性反之降低. 利用材料的光催化储能特性,在黑暗条件下对罗丹明B的降解率为11％,显示了一定的储能降解活性.     

SnO2-Sb2O3基压敏陶瓷致密化及脉冲电流耐受特性

实验研究了TiO₂、Co₃O₄、Cr₂O₃、Ni₂O₃和MnO掺杂对SnO₂-Sb₂O₃基压敏陶瓷材料微观结构和电性能的影响. 研究结果表明, TiO₂和Co₃O₄促进SnO₂陶瓷烧结致密化, 根据XRD图谱分析结果, Co₃O₄与SnO₂反应形成了Co₂SnO₄晶相, TiO₂则固溶于SnO₂晶相;Sb元素的引入能够促进SnO₂晶粒的半导化;复合添加Cr₂O₃、Ni₂O₃和MnO可以有效提高材料的电压非线性特性和脉冲电流冲击耐受能力. 获得电性能接近实用化的SnO₂压敏陶瓷样品, 其压敏电压V_1mA约为350V/mm, 非线性系数α达到50, 漏电流小于5μA, 并且在8/20μs脉冲电流冲击试验中,直径14mm的样品能够经受2kA的脉冲峰值电流.     

Ti3SiC2-64vol%SiC复相陶瓷高温氧化机理研究

采用热等静压原位合成了高致密的Ti₃SiC₂-64vol%SiC复相陶瓷. 通过热重实验研究其在1100~1450℃中空气气氛的高温氧化行为和机理. 研究显示,复相陶瓷的等温动力学曲线遵循抛物线型氧化或抛物线型直线型氧化规律. SiC (64vol%)的引入显著提高了Ti₃SiC₂-SiC材料的抗氧化能力. XRD及SEM-EDS分析显示,氧化膜由外层金红石型TiO₂和非晶态SiO₂组成,过渡层为TiO₂与SiO₂混合物. 高温下（1400℃）,非晶态SiO₂的形成改变了TiO₂膜的生长形态,形成致密TiO₂膜,有效阻碍了氧的扩散. 长时间氧化其抛物线速率常数比在1200℃下氧化低一个数量级. 材料在1400℃下的抗氧化性能明显优于在1200℃下的抗氧化性能.     

并关于O—3型铁电复合材料的热极化机构

制备了以PVDF为母体的TGS、BaTiO₃、LiNbO₃及PZT的O—3型复合材料．研究了这些材料的长时间极化弛豫,发现存在三种带有不同弛豫时间的驰豫机构,这些机构分别由晶粒、母体及晶粒边界产生,晶粒边界产生的极化较稳定．     

ZrO2对NiO/CeO2/γ-Al2O3复合催化剂结构的影响

以Ni(NO₃)_2·6H₂O、Al(NO₃)₃·9H₂O、ZrOCl_2·8H₂O和Ce(NO₃)_3·6H₂O为原料,采用共沉淀法分别制备了NiO/CeO₂/γ-Al₂O₃和NiO/CeO₂-ZrO₂/Al₂O₃催化剂.通过X射线衍射（XRD）、透射电子显微镜（TEM）和近边X射线吸收精细结构（XANES）等方法对催化剂的组成结构进行表征.结果表明,煅烧温度高于600℃时,NiO/CeO₂/γ-Al₂O₃催化剂中的NiO与γ-Al₂O₃载体发生作用,形成NiAl₂O₄尖晶石;而NiO/CeO₂-ZrO₂/Al₂O₃催化剂中,NiO能够稳定存在,没有NiAl₂O₄尖晶石生成,且Al₂O₃与CeO₂和ZrO₂作用形成一种新的Zr_0.30Ce_0.45Al_0.25O_1.87固溶体.     

聚吡咯/二氧化钛复合薄膜的制备及气敏性研究

运用静电力自组装和原位化学氧化聚合相结合的方法制备了聚吡咯/纳米二氧化钛(PPy/TiO₂)复合薄膜, 并进行了紫外－可见光谱分析和原子力显微镜分析. 采用平面叉指电极制备了PPy/TiO₂复合薄膜气体传感器, 研究了其在常温下对有毒气体NH₃和CO的敏感性. 最后测试了该传感器的温度湿度特性. 结果表明, 该传感器对NH₃具有较高的灵敏度, 对CO几乎没有响应. 同时讨论了复合薄膜沉积时间对气敏特性的影响, 实验表明当沉积时间为20min时, 该传感器的NH₃敏感特性最好.     

原位溶剂热和热压制备微纳复合n型CoSb3及热电性能

在块体材料中引入纳米组元构建微纳复合材料是热电材料研究的一个新方向. 采用原位溶剂热和热压方法制备了由纳米晶粒和微米晶粒组成的n 型CoSb₃复合材料. 以CoCl₂、SbCl₃为原料, NaBH₄为还原剂, 乙醇为溶剂, 与熔炼制备的n型CoSb₃微米级别的粉末一起放入高压反应釜中, 在250℃下反应72h得到微纳复合的粉末材料, 热压后得到微纳复合的块体材料. 性能测试结果表明, 该材料表现为典型掺杂半导体的导电特征, 具有较好的电学性能. 微纳复合结构引入大量晶界增强了声子散射, 能有效降低材料的热导率, 并且由纳米组元引起的量子效应能提高材料的Seebeck系数, 使材料的热电性能得到改善. 本工作所制备的微纳复合n型CoSb3具有较低的热导率, 在测试温度范围内, 热导率为2.0～2.3W·m^-1·K^-1. 材料的最大无量纲热电优值在600K时达到0.5.     

包覆型高岭土/二氧化钛纳米复合颗粒的电流变效应

采用溶胶-凝胶法制备了一种新型高岭土/二氧化钛纳米复合电流变液材料.XRD、FT-IR、SEM分析表明TiO₂以纳米晶的形态包覆于高岭土表面.电流变性能测试表明,不同的TiO₂质量比的复合颗粒电流变液效应不同,且都比纯高岭土电流变有显著提高.同时当复合颗粒中TiO₂质量百分比在34％,颗粒硅油体积分数为25％,直流电场为3kV/mm时,高岭土/二氧化钛纳米复合材料电流变液的静屈服应力达3.4kPa,是纯高岭土电流变液的5倍.     

锂离子电池正极材料Li1+xV3O8的合成及性能研究

研究了一种新型制备锂离子电池正极材料Li_1+xV₃O₈的工艺方法.以NH₄VO₃为原料,通过淬火法制备出V₂O₅溶胶,加入LiOH溶液后,通过喷雾干燥法制备球形前驱体,再通过一定的热处理即制得锂离子电池正极材料Li_1+xV₃O₈.试验中,进行了前驱体的DTA/TGA分析;对产物进行了XRD、SEM及电化学性能测试研究.结果表明,经过350℃热处理24h后得到的样品颗粒细小、呈球形、粒径分布均匀、结晶度好,并且还表现出很好的电化学性能,其首次放电比容量高达378mAh·g^-1,经过10次充放电循环后,其放电比容量为312mAh·g^-1.     

ABO3型钛铁矿结构化合物的容差因子

通过结构解析, 建立了ABO₃型钛铁矿的容差因子计算公式以评估结构的稳定性, 经过分析具有钛铁矿结构的MgTiO₃、NiTiO₃、CoTiO₃、ZnTiO₃以及(Zn_1-x, M_x )TiO₃(M为Mg、Ni、Co)复合钛铁矿的稳定性, 验证了容差因子公式的合理性; 通过对已发现的具ABO₃型钛铁矿结构的化合物的统计分析, 提出形成稳定钛铁矿结构的经验容差因子范围和经验电负性差值, 即: t>0.80, e>1.465.     

Electrospun La₀.₈Sr₀.₂MnO₃ nanofibers for a high-temperature electrochemical carbon monoxide sensor

Lanthanum strontium manganite (La(0.8)Sr(0.2)MnO(3), LSM) nanofibers have been synthesized by the electrospinning method. The electrospun nanofibers are intact without morphological and structural changes after annealing at 1050?°C. The LSM nanofibers are employed as the sensing electrode of an electrochemical sensor with yttria-stabilized zirconia (YSZ) electrolyte for carbon monoxide detection at high temperatures over 500?°C. The electrospun nanofibers form a porous network electrode, which provides a continuous pathway for charge transport. In addition, the nanofibers possess a higher specific surface area than conventional micron-sized powders. As a result, the nanofiber electrode exhibits a higher electromotive force and better electro-catalytic activity toward CO oxidation. Therefore, the sensor with the nanofiber electrode shows a higher sensitivity, lower limit of detection and faster response to CO than a sensor with a powder electrode.     

Pt/YSZ氧传感器的电极电阻和响应特性

应用两电极直流极化法测定了氧传感器在380～800℃中的Pt,空气／YSZ电极电阻,从交流低频阻抗测量外推法测得YSZ的体电阻,可以将YSZ的直流极化从电极的过电位中区分出来．Pt,空气｜（ZrO2）_0．93（Y₂O₃）_0．07｜空气,Pt,电池的直流极化1gI-η作图得出,电极电荷传递系数为2．YSZ体电阻、Pt,空气／YSZ电极电阻和电极交换电流对温度的Arrhenius图,在600℃和570℃附近存在着类似的活化能变化．测量表明;700℃时,氧传感器的测量响应时间≤2．5s．     

Sensor for oxygen evaluation in concrete

This paper includes results from a research work carried out for developing and optimising a sensor to measure the limiting current of oxygen reduction in concrete.Platinum, stainless steel and carbon steel materials were tested as working electrodes in saturated Ca(OH)₂ solution. Linear correlations were obtained between the limiting currents of oxygen reduction and the oxygen concentration in solution.The measurements of the limiting current density due to oxygen reduction have been made in concrete specimens with a sensor consisting of platinum and stainless steel, as working electrodes, graphite, as a counter electrode, and activated titanium, as a reference electrode, under different conditions of water and oxygen accessibility to the concrete. The results show that this sensor detects oxygen content variations in the interstitial solution of the concrete, providing qualitative information about the evolution of oxygen availability in concrete.     

Effect of composition on the polarization and ohmic resistances of LSM/YSZ composite cathodes in solid oxide fuel cell

\(\hbox {La}_{0.8}\hbox {Sr}_{0.2}\hbox {MnO}_{3-\delta }\) (LSM)/8 mol% yttria-stabilized \(\hbox {ZrO}_{2}\) (YSZ) (LSM/YSZ) composite cathodes with varying composition are studied for both polarization and ohmic resistance by electrochemical impedance spectroscopy. It was found that total resistance and polarization resistance are lowest for the composite with 60 wt% of LSM (LSM60/YSZ40). However, the ohmic resistance was highest for the same composition and amounted to 60% of the total resistance value. Compositional dependence of resistances has been explained based on the variations of the triple phase boundaries and width of the \(\hbox {O}^{2-}\) ion migration path with the composition of the electrode. Based on the observed area specific ohmic resistance values for the composite cathodes, it is proposed to verify the advantages of LSM/YSZ over LSM cathode in anode-supported solid oxide fuel cell with thin electrolyte.     

电子迁移对钇稳定氧化锆电解质性能的影响

本文讨论了在不同测氧分压、温度、相对密度及引入Al2O3下,电子迁移对钇稳定氧化锆电解质性能的影响。结果表明：氧化锆氧浓差电池测量的氧分压越低,电子迁移对池电势的影响越大;电池的工作温度越低,电子迁移数越大,测量误差越大;烧结越致密的电解质其电子迁移数越小;适量的引入Al2O3可以降低电子迁移数,提高测氧准确性。     

Microstructural characterisation by X-ray scattering of perovskite-type La<Subscript>0.8</Subscript>Sr<Subscript>0.2</Subscript>MnO<Subscript>3±δ</Subscript> thin films prepared by a dip-coating process

The La_0.8Sr_0.2MnO₃ (LSM) cathode materials are widely used in solid oxide fuel cells (SOFCs) as electronic conductors. In such materials, the reduction of oxygen is located at the triple contact boundaries: air/cathode LSM/electrolyte which is generally Yttria Stabilised Zirconia (YSZ). In order to improve the chemical reactions at these air/cathode LSM/electrolyte interfaces, the triple phase boundary length has to be optimised. In this aim, we have first synthesised the La_0.8Sr_0.2MnO₃ phase by a sol–gel route and, second, LSM thin films have been deposited on various polished substrates by using a dip-coating process. The structure and microstructure of the resulting LSM thin layers have been investigated by using well suited complementary techniques such as X-ray reflectometry, grazing incidence small angle X-ray scattering, X-ray diffraction and scanning electronic microscopy. The structural and microstructural parameters of LSM thin films have been managed and studied as a function of synthesis parameters such as initial metallic salt concentration, time and temperature of annealing. The higher the metallic salt concentration, the higher the thickness of the film, the smaller the film density. The as-prepared layers are amorphous and the single crystallised perovskite form is obtained for low temperature heat treatments. Therefore, the annealed coatings are constituted by randomly oriented LSM nanocrystals, which organise in a more or less dense close-packed microstructure according to the initial metallic salt concentration.     

用电泳沉积-电沉积联合法制备二氧化锆(YS Z)薄膜

先用电泳法在掺锶锰酸镧（La0.8Sr0.2MnO3-LSM）基片沉积一层钇稳定二氧化锆（yttria-stabilized zirconia-YSZ)薄膜,在烧结后的电泳薄膜上进行若干次电沉积和烧结。以封堵薄膜中孔隙进行。上述联合法综合了电泳沉积薄膜附着力强,烧结时不龟裂的优点和电沉积薄膜的颗粒细,易烧结性的优点,较好地解决了电化学沉积膜难以烧结致密的问题。制备出的薄膜致密性高,厚度为8～14um。     

Functionally graded cathodes for solid oxide fuel cells

Functionally graded Solid Oxide Fuel Cell cathodes have been prepared from mixtures of strontium doped lanthanum manganite (LSM) and yttria stabilised zirconia (YSZ) using screen printing techniques. Samples were characterised using scanning electron microscopy, elemental dot mapping, and electrochemical impedance spectroscopy. Characterisation using AC impedance techniques showed that each cathode could be analysed in terms of a low frequency, mid frequency and high frequency response. Results showed that as the level of YSZ-LSM grading within the cathode increased, the polarisation resistance decreased. No region of the graded cathode should contain less than 20 wt% LSM to prevent an accompanying increase in series resistance.     

La1−xSrxCuO2.5−δ as new cathode materials for intermediate temperature solid oxide fuel cells

La_1−xSr_xCuO_2.5−δ (LSCu), which exhibit excellent electrical conductivity and oxygen vacancies were investigated as potential cathode materials for solid oxide fuel cell (SOFC) applications. The structure stability, electrical conductivity, cathodic overpotential, and the reactivity with yttria-stabilized zirconia (YSZ) were examined in this study. It was found that the LSCu perovskite was obtained only when the addition of strontium fell in the range between 15 and 30%. With more than 20% of strontium addition, this material showed excellent electrical property and immunity to the reaction with YSZ at 800 °C. The conductivities of LSCu were as high as 900 S/cm at 600 °C, and 800 S/cm at 800 °C. The cathodic overpotential of this material was approximately 3.8 and 10.6 mV at a current density of 100 mA/cm² at 850 and 750 °C, respectively. These properties are superior to Sr-doped lanthanum manganite (LSM), which is the state-of-the-art cathode material of SOFCs.     

高温水蒸汽对CO2电化学传感器性能的影响

使用锂钡掺杂氧化碳酸盐作为敏感电极材料制备YSZCO₂电化学传感器,研究了高温水蒸汽对传感器性能的影响。结果表明,经300℃高温水蒸汽处理(24~120 h)后,传感器对CO₂浓度的变化(271~576802 μL/L)仍然表现出准确的响应特性,电子转移数接近理论值2;未经高温水蒸汽处理和经高温水蒸汽处理120 h的传感器,均表现出较低的氧含量依赖特性,在不同的氧含量条件下传感器对CO₂浓度突变的响应电动势相同。这种传感器不但能在含有一定比例水蒸汽的环境中长时间工作,而且在经过一定程度的高温水蒸汽累积作用后其性能没有明显的劣化。