纳米晶La0．8Sr0．2FeO3气敏元器件的制备与乙醇敏感特性

采用溶胶-凝胶法制备了纳米晶La0.8Sr0.2FeO3。X射线衍射表明：该样品为正交晶系钙钛矿结构，其平均粒径约为31nm。将La0.8Sr0.2FeO3纳米晶粉体与聚乙烯醇PVA混合固化，然后在400℃下分别退火20min和120min。固化退火120min的元器件电阻随乙醇浓度的增加而增加，元器件具有P型半导体特性。而固化退火20min的元器件电阻随乙醇浓度的增加而减小，该元器件具有n型半导体特点。固化退火120min的La0．8Sr0．2FeO3元器件的气敏灵敏度S=Rg／Ra在80℃下高达100，低工作温度、高灵敏度特性对应用有益。发现La0.8Sr0.2FeO3元器件的电阻R和乙醇浓度C只在较低温区符合指数关系（R≈KC^α）。     

钙钛矿型锰氧化物La0.8Sr0.2MnO3的高频性能

采用溶胶-凝胶法制得La0.8Sr0.2MnO3氧化物多晶样品。通过XRD、SEM对样品的微观结构进行了分析,结果表明:所得样品为钙钛矿结构,样品的颗粒大小比较均匀,平均粒度约100nm。利用阻抗分析仪对样品的介电常数和磁导率的频谱(10MHz～1GHz和1MHz～1GHz)进行了研究。研究表明,在整个测试频率范围内,La0.8Sr0.2MnO3的介电常数实部和虚部随频率的升高而降低。La0.8Sr0.2MnO3的复磁导率的频谱谱线为典型的弛豫型谱线,磁导率实部在1MHz时为6.2,共振频率fr为50MHz,共振时虚部峰值为2.8;磁谱测试表明材料的弛豫损耗峰出现在频率f≤300MHz的频率范围内,在此频率区域引起损耗的机制主要是畴壁共振。     

AgI纳米粒子水溶胶的制备与表征

采用沉淀法制备了AgI纳米粒子水溶胶，对制备水溶胶的条件进行了系统的研究。TEM分析表明，AgI纳米粒子呈球形，粒径小于50nm，粒径分布均匀，无明显团聚现象；ED分析表明，AgI纳米粒子为多晶结构，其中有少量的发育良好的单晶颗粒存在。     

溶胶-凝胶法制备固体氧化物燃料电池复合阴极

用溶胶-凝胶法制备了中温固体氧化物燃料电池的50w/%Sm0.2Ce0.8O1.90(SDC)+50w/%(La0.85Sr0.15)0.9MnO3-8(LSM)复合阴极.阴极-电解质(SDC)界面电阻深受阴极微结构的影响用溶胶凝胶法制备的阴极具备有利于氧还原反应的微结构,包括小的粒径、高的孔隙率、高的比表面积等.而微结构又受到烧结温度的影响,界面电阻最小时的烧结温度为950℃.800℃时界面电阻为0.14Ωcm2,明显低于其他方法制备的同化学成分阴极的界面电阻.     

溶胶-凝胶法制备La0.8Sr0.2CoO3纳米材料

以La(NO3)3·6H2O、Sr(NO3)2、Co(NO3)2·6H2O为原料,用EDTA络合溶胶-凝胶法制备La0.8Sr0.2CoO3凝胶,在700℃、800℃、900℃煅烧,制得La0.8Sr0.2CoO3粉体.用DTA、FT-IR、XRD、SEM等手段对制备过程、热分解机理及粉体的性能进行了研究.在700℃焙烧2 h得到La0.8Sr0.2CoO3纯相纳米粉,颗粒呈球形.选取700℃焙烧2 h的La0.8Sr0.2CoO3粉体制成管状传感器,进行NO2敏感性能测试,探讨了相同NO2浓度下,传感器敏感信号与温度的关系.结果表明:纳米La0.8Sr0.2CoO3粉体在450℃时对NO2的敏感信号最大,输出的电动势信号与NO2浓度之间呈线性关系.     

Emissivity of La1-xSrxMnO3/acrylic Resin Thermal Control Coating

Thermal control coatings were fabricated by mixing of La1-xSrxMnO3(LSMO)powder and acrylic resin and brushed on Al alloy substrate.The powders of La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 were prepared using sol-gel method.XRD results reveal the phase structure of LSMO powders are perovskite.The transition temperature from metal to insulator of La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 are 300 and 275 K,respectively.The emissivity evolution with temperature of the coatings was measured.For La0.7Sr0.3MnO3/acrylic resin coating,the emissivity increases from 0.56 to 0.88,and for La0.7Sr0.3MnO3/acrylic resin coating from 0.50 to 0.90.     

MoO3纳米有机溶胶的制备与光致变色性质研究

采用表面活性剂CTAB对MoO3水溶胶中的纳米粒子进行表面修饰，通过正戊醇萃取制备了MoO3纳米有机溶胶，对制备有机溶胶的条件进行了系统地研究。TEM分析表明，MoO3纳米粒子呈球形，粒径约为40nm，粒度分布均匀。ED分析表明，MoO3纳米粒子为多晶结构。UV-VIS分析表明，MoO3纳米有机溶胶具有较好的光致变色特性。     

La0．5Sr0．5MnO3纳米晶体的制备与电磁性能研究

以柠檬酸为络合剂，采用溶胶-凝胶（sol—gel）自燃烧方法制备了La0．5Sr0．5MnO3纳米晶体。使用FT-IR，DSC—TG，XRD，波导方法对反应、反应产物以及反应产物的电磁性能进行了研究。结果表明，在凝胶中，金属离子与柠檬酸以络合物的形式存在。凝胶在273℃基本完成自燃烧反应。生成的La0．5Sr0．5MnO3纳米晶体为钙钛矿结构，随着反应温度的提高，产物的粒径逐渐增大。电磁性能结果表明，La0．5Sr0．5MnO3在8GHz～12GHz的微波范围内具有明显的介电损耗。随着厚度的增加，混合媒质的反射率逐渐增加，反射率吸收峰随着厚度的增加向低频移动。     

AgCl与Cu^2＋共存纳米溶胶的制备与表征

采用沉淀法制备了AgCl与Cu^2 共存的纳米水溶胶，油酸萃取并包覆AgCl与Cu^2 共存的纳米水溶胶，制备了AgCl与Cu^2 共存的纳米有机溶胶，对水溶胶和有机溶胶的制备条件进行了系统的研究。TEM分析表明，AgCl纳米粒子呈球形，粒径约50nm，粒度分布均匀，无明显团聚现象。ED分析表明，AgCl纳米粒子为多晶结构，其中有少量的单晶存在。表面包覆油酸的AgCl纳米粒子易溶于弱极性溶剂，难溶于极性溶剂。     

不同晶粒尺寸的(La0.47Gd0.2)Sr0.33MnO3纳米颗粒磁性能

采用非晶态多核配合的方法制备了(La0.47Gd0.2)Sr0.33MnO3纳米颗粒,用XRD、HRTEM和MPMS等手段对纳米颗粒的微观结构和磁性能进行研究。XRD和SAD分析表明,所有的样品都具有单相钙钛矿结构;TEM分析表明, 经过600,800和1000 ℃烧结10 h后的样品颗粒尺寸分别为40~50 nm,90~100 nm和140~150 nm。样品的磁学性能结果表明：(La0.47Gd0.2)Sr0.33MnO3纳米颗粒的居里温度TC (298 K)基本上不随颗粒尺寸的变化而变化,而相对磁制冷能力取决于颗粒尺寸;颗粒尺寸为90~100 nm的(La0.47Gd0.2)Sr0.33MnO3纳米颗粒的相对磁制冷能力最大,可以作为室温下使用的磁制冷工质侯选材料。     

Ca缺位型稀土金属氧化物La_(0.65)Ca_xMnO_3的磁电特性分析

制备了 Ca缺位型稀土金属氧化物 L a0 .6 5Cax Mn O3,并对磁性及电输运特性进行了研究。发现随 Ca缺位的增加 ,材料的晶胞体积增大 ,但居里温度却减小 ,铁磁相互作用减弱。材料的金属 -半导体转换峰值温度 Ttran随 Ca缺位程度的增加相应减小而电阻峰值却增大 ,作者用极化子电阻模型拟合了金属 -半导体转换峰温度 Ttran以上的电阻温度依赖关系 ,发现 Ca缺位材料电阻的增大可能与局域波函数的衰减长度减小有关。还同时利用迪尼模型在 10 0 K～ 3 0 0 K温区内 ,分析计算了材料电阻随温度的变化关系 ,发现磁交换能和电 -声相互作用能对极化陷阱能的贡献在有 Ca缺位时比无缺位时均有所增大。极化陷阱能的增高减低了载流子的活动能力。同时还对 Ca含量、Mn+ 3/ Mn+ 4含量、氧缺位量存在的关系进行了讨论。     

Y_(0.08)Sr_(0.92)TiO_(3+δ)/Gd_(0.2)Ce_(0.8)O_(1.9)双相混合导体合成及在氧传感器中应用

以SrCO_3、TiO_2、Y_2O_3、CeO_2及Gd_2O_3为原料,用传统固相烧结法在不同温度下制备了一系列比例(体积比)的Y_0.08Sr_0.92TiO_(3+δ)/Gd_0.2Ce_0.8O_1.9(CGO)双相复合混合导体材料.用Archimedes法、SEM 、XRD、 EIS等手段对材料的致密度、微观结构、化学相容性及导电性能进行了研究.结果表明,1600 ℃烧结的40% (体积分数, 下同)YST/60% CGO的试样相对体密度达到了99%,未发生相转变,化学相容性较好且电导率较高.以40%YST/60%CGO的粉体作为混合导体制备极限电流传感器,进行O_2敏感性能测试.结果表明:传感器在氧浓度低于0.1%,温度范围在600～700℃内,极限电流随氧浓度增大而增大,二者具有较好的线性关系.实验证明YST/CGO混合导体材料可以作为限流型氧传感器的扩散阻使用.     

La_(0.8)Sr_(0.2)CoO_3基阻抗谱型厚膜NO_2传感器的研究

以La_2O_3、SrCO_3和Co_3O_4为原料,采用高温固相反应法制备了La_0.8Sr_0.2CoO_3(LSC)粉体.采用丝网印刷涂膜法在Y_2O_3稳定的ZrO_2(YSZ) 固体电解质表面制备LSC膜层,经1400 ℃煅烧,制成厚膜型NO_2传感器.采用扫描电子显微镜(SEM)观察其断面形貌.采用交流阻抗技术对NO_2敏感性能进行测试.研究了氧气浓度和LSC厚度对传感器阻抗值的影响.结果表明:LSC膜层均匀致密,且与YSZ结合良好.传感器的阻抗值随NO_2浓度的增加而迅速减小,敏感性能良好.氧气体积分数越大,LSC膜层厚度越小,传感器低频区阻抗值越大.     

IT-SOFC复合阳极材料CDC-LSCMCo的制备及性能

采用甘氨酸-硝酸盐法(GNP法)一次性合成固体氧化物燃料电池复合阳极材料Ce0.8Ca0.2O2-La0.7Sr0.3Cr0.5Mn0.5-xCoxO3-δ(CDC-LSCMCo)。XRD、SEM和EDS分析结果表明:1350℃下烧结5h能够得到单一萤石-钙钛矿结构且粒度较小(1μm左右)的复合阳极粉体。电导率的测试研究发现,温度大于750℃时,电导率随Co含量的增加而增大。800℃时,CDC-LSCMCo0.15分别在空气与氢气气氛下的电导率分别为10.5和0.7S·cm-1。SEM和XRD分析表明:CDC-LSCMCo与La0.9Sr0.1Ga0.8Mg0.2O3-δ电解质材料有很好的热与化学相容性,是一种应用前景良好的IT-SOFC阳极材料。     

La_xSr_(1-x)TiO_3氧化物热电材料的制备与电传输性能

利用溶胶凝胶(sol-gel)法和放电等离子烧结(SPS)制备了单相的钙钛矿结构La_xSr_(1-x)TiO_3 (0≤x≤0.15)块体材料,与传统的固相反应法相比,烧结温度大幅降低.在室温至679 K的温度范围内测量了La_xSr_(1-x)TiO_3 (0≤x≤0.15)的Seebeck系数和电导率,确定了最佳La掺杂量x=0.08.La_0.08Sr_0.92TiO_3在679 K时,最大功率因子PF=2.95 μWm~(-1)·K~(-2),随温度升高,PF增大趋势明显,表明在高温环境中可具有更大的PF.     

Enhancement of room-temperature magnetoresistance in La0.5Sm0.2Sr0.3MnO3/（Ag2O）x/2

La0.5Sm0.2Sr0.3MnO3/(Ag2O)x/2 (x = 0.00, 0.04, 0.08, 0.25, 0.30) samples were prepared by the solid-state reaction method, and their transport behaviors, transport mechanism, and magnetoresistance effect were studied through the measurement and fitting of ρ-T curves. The results show that the element Ag takes part in reaction when the doping amount is small. Ag is mainly distributed at the grain boundary of the host material and is in metallic state when the doping amount is relatively large; then the system becomes a two-phase composite. A small amount of Ag doping can apparently increase grain-boundary magnetoresistance induced by the spin-dependent scattering. The resistivity of the sample doped with 30 mol% Ag is one order of magnitude smaller than that of low-doped samples, and its magnetoresistance in the magnetic field of 0.5 T and at 300 K is strengthened apparently reaching 9.4%, which is connected not only with the improvement of the grain-boundary structure of the host material but also with the decrease of material resistivity.     

Absence of superconductivity in Nd_(0.8)Sr_(0.2)NiO_x thin films without chemical reduction

The recently reported 9-15 K superconductivity in Nd_(0.8)Sr_(0.2)NiO_2/SrTi03 heterostructures that were fabricated by a soft-chemical topotactic reduction approach based on precursor Nd_(0.8)Sr_(0.2)NiO_3 thin films deposited on SrTiO_3 substrates,has excited an immediate surge of research interest.To explore an alternative physical path instead of chemical reduction to realizing superconductivity in this compound,using pulsed laser deposition,we systematically fabricated 63 Nd_(0.8)Sr_(0.2)NiO_x(NSNO) thin films at a wide range of oxygen partial pressures on various oxide substrates.Transport measurements did not find any signature of superconductivity in all the 63 thin-film samples.With the oxygen content reducing in the NSNO films by lowering the deposition oxygen pressure,the NSNO films are getting more resistive and finally become insulating.Furthermore,we tried to cap a 20-nm-thick amorphous LaAlO_3 layer on a Nd_(0.8)Sr_(0.2)NiO_3 thin film deposited at a high oxygen pressure of 20 Pa to create oxygen vacancies on its surface and did not succeed in obtaining higher conductivity either.Our experimental results together with the recent report on the absence of superconductivity in synthesized bulk Nd_(0.8)Sr_(0.2)NiO_2 crystals suggest that the chemical reduction approach could be unique for yielding superconductivity in NSNO/SrTiO_3 heterostructures.However,SrTiO_3 substrates could be reduced to generate oxygen vacancies during the chemical reduction process as well,which may thus partially contribute to conductivity.     

Synthesis and characterization of La0.8Sr0.2MO3−δ (M=Mn, Fe, or Co) cathode materials by induction plasma technology

In this work, nanopowders of perovskite cathode materials (La_0.8Sr_0.2MnO_3−δ, La_0.8Sr_0.2FeO_3−δ, and La_0.8Sr_0.2CoO_3−δ), for use in solid oxide fuel cells (SOFC), were successfully synthesized, using induction plasma techniques. Their compositions, structures, morphology, particle size distributions, and BET specific surface areas were determined for comparison with their counterparts prepared by the Pechini method and by the glycine-nitrate combustion (GNC) technique. The particle sizes of the plasma-synthesized powders are mostly around 63 nm. These plasma-synthesized powders are generally globular, their BET specific surface areas being about 26 m²g⁻¹, approximately twice those of powders prepared by the GNC and Pechini methods. These plasma-synthesized powders are readily reproducible and are not agglomerated. Their individual particle sizes and distributions are very independent of their composition.     

Preparation of nanometer perovskite-type oxide La0.8Sr0.2MnO3 by organic solvent sol-gel method and capability testing

A perovskite-type oxide, La0.8Sr0.2MnO3, was synthesized by the organic solvent sol-gel method. The desired metal cations were chelated in a solution by using citric acid as the chelating agent and absolute ethanol as the solvent. The thermal decomposition of the metal carboxylate precursor gels was studied by thermogravimetric/differential thermal analyzer （TG/DTA） and the products derived from calcining the gels were characterized by X-ray diffraction （XRD） and transmission electronic microscope （TEM）. The polarization curves were acquired on an electrochemical workstation （LK98） and the discharge curves were acquired on a testing instrument of batteries （DC-5）, with a constant current discharge, less than 120 mA/cm^2. The results revealed that the nanometer perovskite-type powder with lesser particle size could be achieved with an organic solvent and had a better catalytic activity.     

表面活性剂对球磨法制备纳米Sb2O3粉末的影响

采用球磨法制备纳米Sb2O3粉末,研究表面活性剂对制备纳米Sb2O3的影响。采用X射线衍射仪、透射电子显微镜、红外光谱仪研究了球磨产物的物相组成、颗粒形貌以及平均粒径。研究结果表明表面活性剂对产物的Sb2O3含量、结晶度、粒径大小、形貌以及分散性具有显著地影响。当硬脂酸、辛基酚聚氧乙烯醚、聚丙烯酸钠作为表面活性剂时,球磨产物中Sb2O3的含量低于92%,颗粒大小不均匀,甚至出现团聚现象。当辛基酚聚氧乙烯醚与聚丙烯酸钠复配作为表面活性剂时,产物中Sb2O3含量为94%,颗粒形貌不规则。当聚丙烯酸钠与硬脂酸复配作为表面活性剂时,球磨产物中Sb2O3的含量达99%以上,分散性最好,粒径分布在10~20 nm之间,平均粒径15 nm左右。