共沉淀法合成新型阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-σ

草酸共沉淀法合成了中温固体氧化物燃料电池（ITSOFC）新型阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-σ（BSCF）。XRD，DSC和SEM结果显示：经过900℃煅烧2h后，产物的钙钛矿结构已经初步形成，但由于晶化不完全，衍射峰强度相对较弱，且存在杂相；随着煅烧温度提高到1200℃后，产物中杂相消失，晶体结构转变为单一的立方型钙钛矿，颗粒大小基本在2μm～3μm；BSCF与Ce0．8Sm0．2O1．9（SDC）混合物（质量比1：1）在1000℃下热处理24h后未发现杂相，表明BSCF与SDC具有良好的化学相容性。     

La0.6Sr0.4Co0.8Fe0.2O3-δ超细粉体的溶胶凝胶-自燃烧法制备及其性能表征

采用溶胶凝胶-自燃烧法合成La0.6Sr0.4Co0.8Fe0.2O3-δ(LSCF)复合氧化物粉体,用XRD、TG-DTA、TEM等对产物形成过程及微观结构进行了表征.结果表明,溶胶凝胶-自燃烧法一步合成了粒径为30～70nm的具有钙钛矿结构的La0.6Sr0.4Co0.8Fe0.2O3-δ超细粉体,粉体具有较高烧结活性,1100℃下烧结2 h相对密度达到95%.利用热膨胀仪测量发现样品从室温到1000℃的平均膨胀系数为19.3×10-6/K;直流四探针法电导测试表明,样品在200～600℃温度范围内电导率随温度的升高而升高,由580 S·cm-1升至最大值1000 S·cm-1,在600℃后样品的电导率随着温度的升高缓慢降低,样品的电导率在200～800℃温度范围内均高于580 S·cm-,能很好地满足中低温SOFC的使用要求.     

Zn2SiO4微波陶溶胶-凝胶法制备及性能研究

以Zn(NO3)2·6H2O和正硅酸乙酯为前驱体,乙醇作为溶剂,采用溶胶-凝胶法制备了ZnzSiO4微波陶瓷粉体,并研究了粉体的烧结特性和微波介电性能.干凝胶在800℃热处理后得到的ZnO和Zn2SiO4纳米级混合粉体.溶胶凝胶法制各的粉体具有更大的比表面积,使作为粉体烧结驱动力的表面能剧增,促使陶瓷在1200～1350℃实现致密烧结,比固相法合成粉体的烧结温度降低近200℃,并具有优异的介电性能:εr=6.14,Qf=67,500 GHz(12 GHz).     

表面修饰对La0.6Sr0.4Co0.2Fe0.8O3-δ阴极性能 及稳定性的影响研究

本研究采用一步溶液浸渍法成功对La0.6Sr0.4Co0.2Fe0.8O3-δ（LSCF）表面进行了La2NiO4+δ（LNO）纳米颗粒修饰。扫描电镜分析显示,LNO纳米颗粒均匀分布在LSCF表面,颗粒粒径约在50-250 nm之间。电化学测试表明,与空白LSCF相比,修饰了LNO的阴极极化电阻降低了41%~50%,并且稳定性有明显提高：在750℃保温约125 h后,其极化电阻仅增大了50.42%,而空白LSCF阴极则增大了76.89%。X射线衍射分析表明在750℃保温100 h后LNO-LSCF表面出现了La2SrOx相。X光电子能谱分析表明,长期保温100 h后,LNO-LSCF阴极的表面Sr含量比保温前减少了3.66%,而空白LSCF阴极则增多了27.95%,说明通过表面修饰LNO成功抑制LSCF表面的Sr偏析。     

Li_3V_2(PO_4)_3溶胶-凝胶-微波合成工艺优化及性能研究

用溶胶-凝胶-微波法制备了锂离子电池正极材料Li3V2(PO4)3样品,用正交试验法考察了影响样品性能的因素,分析并优化了工艺。XRD、SEM和电化学测试表明:该方法所制备的样品为单斜结构,粒径尺寸0.2～1μm,颗粒分布比较均匀。锂源为Li2CO3、反应物摩尔比为Li∶V=3.0∶2.0、微波时间为25 min时,为最佳合成工艺条件。在此优化条件下,3.0～4.3 V区间内0.2 C放电比容量达到106 mAh/g,交换电流密度高达6.17×10-6 A/cm2。     

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.     

La0．75Sr0．25Cr0．5Mn0．5O3粉末的溶胶-凝胶法制备及其NO2气敏性能研究

以La2O3、Cr（NO3）3·9H2O、Sr（NO3）2、Mn（NO3）2和柠檬酸为原料，用溶胶-凝胶法制备了La0.75Sr0.25Cr0．5Mn0.5O3粉体。使用DTA、XRD、SEM、FT-IR等对粉体及中间体进行了表征。结果表明，用此法制备的前驱体，经700℃焙烧2h即可制得粒度均匀的晶体，其平均粒径为4．87nm。以制得的粉体为气敏材料制备了管状NO2气体传感器，并测试了传感器的性能。结果表明，La0.75Sr0.25Cr0.5Mn0．5O3材料对NO2具有良好的敏感性能。在一定温度范围内，随着NO2浓度的升高，传感器电动势信号逐渐增大。在测试温度范围内，电动势与NO2浓度之间呈良好的线性关系。     

Microwave absorbing properties of La0.8Ba0.2MnO3 nano-particles

La0.8Ba0.2MnO3 nano-particles were synthesized by sol-gel process, and the crystal structure and morphology＇ were characterized by XRD and SEM, respectively. The complex permittivity and permeability were determined by microwave vector network analyzer in the frequency range of 2-18 GHz. The relationship between reflection coefficient and microwave frequency of La0.8Ba0.2 MnO3 was calculated based on measured data. The results show that the average diameter of La0.8Ba0.2MnO3 crystal powders is about 80 nm and the crystal structure is perovskite when being calcined at 800 ℃ for 2 h. The microwave absorbing peak is 13 dB at 6.7 GHz and the effective absorbing bandwidth above 10 dB reaches 1.8 GHz for the sample with the thickness of 2.6 mm. The microwave absorption can be attributed to both the dielectric loss and the magnetic loss from the loss tangents of the sample, but the former is greater than the latter.     

纳米氧化物La0.8Sr0.2MnO3的制备研究

用添加表面活性剂的苹果酸溶胶凝胶法制备出纳米钙钛石型氧化物La0.8Sr0.2MnO3。通过差热热失重分析,确定了氧化物的焙烧制度。XRD分析表明,所烧制的氧化物样品特征衍射峰明显,杂峰少,晶形完整,其物相为钙钛石结构。表面活性剂因其亲油基团和亲水基团与胶体粒子可以发生复杂的相互作用,形成胶束和胶团,保护了胶体粒子不长大,从而有效地减小氧化物粉料的颗粒粒径,并且在纳米材料的制备过程中能显著降低纳米微粒的表面张力,从而可防止原生粒子团聚,所以在溶胶的制备过程中添加了表面活性剂聚乙烯醇(PVA)。根据谢乐公式计算得出,添加了PVA后,氧化物粉料的粒径约为17nm。TEM分析表明,聚乙烯醇可以作为纳米氧化物粉体La0.8Sr0.2MnO3的分散剂,添加适量的PVA可使纳米粒子的团聚现象得到了明显改善。     

低温燃烧合成La0.9Sr0.1Ga0.8Mg0.2O2．85固体电解质粉末

低温燃烧合成工艺结合了溶液法和高温自蔓延合成超细粉末工艺的特点，可以在较低的温度下引发化学反应，并利用反应自身的放热效应维持反应的继续进行。在硝酸盐．柠檬酸体系中用该工艺直接合成了比表面积超过120m^2／g的La0.9Sr0.1Ga0.8Mg0.2O2.85固体电解质超细粉末。研究了硝酸盐溶液起始浓度和pH值对产物性能的影响。     

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.     

凝胶注模制备La0．8Sr0．2MnO3多孔阴极材料

采用凝胶注模技术原位合成造孔剂制备出开孔气孔率为20％～30％的La0．8Sr0．2MnO3多孔阴极材料。结果表明，合适的烧结温度为l100℃～1150℃；开口气孔位于三角晶界，中位孔径约为400nm；多孔材料的电导率随着温度的升高而升高，由ln(σT)-1／T曲线，可得电导活化能Ea为10．99kJ／mol。     

螯合物-凝胶法制备La0.8Sr0.2MnO3粉体

以La(NO3)3·6H2O,Sr(NO3)2和Mn(NO3)3·6H2O为起始原料,采用螯合物-凝胶法制备出La0.8Sr0.2MnO3粉体.首先在混合盐溶液中入柠檬酸形成螯合的柠檬酸盐,然后加入单体和交联剂,在引发剂和催化剂的作用下形成湿凝胶.干燥后的前驱体为无定形的,DTA和XRD测试表明晶化温度在400℃～500℃.在500℃～1 200℃范围内煅烧,颗粒尺寸由500℃时的约38 nm 长大到1 200℃时的500 nm.     

La0.6Sr0.4Co0.2Fe0.8O3 protective coatings for solid oxide fuel cell interconnect deposited by screen printing

La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) is applied on a Crofer22 APU interconnect for solid oxide fuel cells (SOFCs) by screen-printing method. The above coated alloy was first checked for their compositions, morphology and interface conditions. It was then tested in a simulated oxidizing environment, 800 °C for 200 h. The results showed that the LSCF film can change the oxidation behavior of Crofer22 APU. After sintering the screen printed alloy was under 1050 °C in N₂ atmosphere, the adhesion between the LSCF layer and alloy substrate is excellent. Long-term electrical resistance measurement indicated that area-specific resistance (ASR) of the alloy with coated film is significantly lower than that of the uncoated. The use of LSCF coating for metallic interconnect could reduce working temperature for solid oxide fuel cell.