Preparation of Perovskite-Type Oxides La1-x Srx Fe1-y Coy O3 Using EDTA Sol-Gel Method

Two series of perovskite-type oxides with composition La1-xSrxFeO3 (x≤0.8)and La1-xSrxFe1-yCoyO3( x = 0.2；y = 0.2, 0.4 ) powder productions were synthesized by EDTA complexing sol-gel method. The products were characterized by XRD, TEM, SEM, BET method (N2 adsorption)and laser granularity analysis for different synthesis conditions to obtain the optimum conditions for the preparation process. Single-phased, uniform perovskite-type oxides with small particle size were obtained by EDTA sol-gel process with high stability and repeatability,and the process temperature is much lower than that of solid state reaction method.     

Synthesis and Characterization of Er3+∶Y3Al5O12 Nanocrystalline Powders Prepared by Sol-Gel Method

Nano-sized Er3 ∶Y3Al5O12 powders was successfully prepared via a simple sol-gel route at as low a temperature at 800 ℃ whereas a temperature much higher is necessary to obtain this compound by solid state synthesis (about 1500 ℃). The phase purity, composition and microstructural features of the materials were analyzed by means of X-ray diffraction(XRD), infrared spectroscopy(IR) and transmission electron microscopy(TEM), and no other intermediate phase were observed to form in the range of 700～1000 ℃. The luminescence spectra of Er3 substituted for Y3 in YAG in 1% content was characterized on samples at different temperature.     

用酒石酸凝胶法制备LaFeO3纳米晶

用酒石酸溶胶-凝胶法制备出纳米LaFeO3材料,粒径30～10nm。用X射线衍射仪和透射电子显微镜对材料的结构、粒径进行了分析和表征。     

LaFeO3溶胶凝胶合成和光催化性能

用溶胶-凝胶法制备了纳米LaFeO3光催化剂。用X射线衍射仪和透射电子显微镜对材料的结构、粒径进行了分析和表征。通过对甲基蓝和腈纶污水的光降解分析,表明La1-xCaxFeO3具有良好的光催化活性。     

Combustion Synthesis, Character and Electromagnetic Properties of Nano-Sized La0.8Sr0.2FeO3 Perovskite

The perovskite-type nanocrystal La0.8Sr0.2FeO3 was prepared using a sol-gel auto-combustion method with citric acid as the chelating agent. The metal ions coordination compound, obtained from nitrate and citrate, underwent an autocombustion process and voluminous ashes formed when calcining the complex in the air. Some analytical methods, which consisted of FT-IR, XRD, TEM and wave-guide, were used to characterize the gel and the final products. It was shown that metal ions and carboxyl were combined to form a homogeneous organic complex base salts in the process of gelation. The nanocrystalline had dielectric loss in the microwave frequency range of measurement.     

SHS法合成La1-xSrxMnO3的烧结性能

采用SHS法制备了SOFC阴极材料La1-xSrxMnO3（LSM）}研究了不同温度下烧结LSM强度、相对密度与掺Sr量的关系，烧结试样的孔隙率以及膨胀系数随温度的变化关系。结果表明；随着Sr含量的增加，合成LSM粉末的粒度增大，烧结试样的相对密度略有降低；较高的烧结温度有利于降低试样的孔隙率；烧结LSM的热膨胀系数与YSZ匹配较好。     

络合溶胶凝胶法制备LaCo1-xCuxO3纳米晶及其对酸性黑10B的光催化降解

以EDTA为络合剂、PEG为分散剂，采用络合溶胶．凝胶法合成LaCo1-xCuxO3复合氧化物纳米晶。通过TG-DTA，XRD，SEM等手段对凝胶的热分解机制、LaCo1-xCuxO3的形成过程、纳米晶的物相结构、微观形貌、粒度大小等进行了研究。结果表明：硝酸根离子可以加速EDTA-凝胶的热分解，仅在600℃焙烧即可得到颗粒细小、组分均匀、钙钛矿型LaCo1-xCuxO3纳米晶，颗粒基本呈球形，粒径为50nm左右。与传统的固相反应相比，该法制得的LaCo1-xCuxO3组分均匀，化学计量比易于控制，烧成温度低。而且，由于EDTA可以和元素周期表中绝大多数金属元素络合，因此，该技术可广泛应用于复杂氧化物体系纳米材料的制备及研究。光催化性质研究发现：在适宜条件下，LaCo1-xCuxO3可使染料酸性黑10B的脱色率达近100％。     

Kinetics Researches of La1-x SrxMnO3 Powder by Microwave Synthesis

The La1 -xSrxMnO3 is the cathode materials of SOFC, which is the key part of SOFC.The production technology of La1 -xSrxMnO3 materials is widely studied with efficiency, saving energy and environment friend.Microwave synthesis was used to produce La1 -xSrxMnO3.The kinetics course of synthesizing La1-xSrxMnO3 materials by microwave technology was discussed.Using DTA-TGA and XRD analysis, the process and principle of solid reaction were examined.The results show that the reaction time and grain size of raw materials are important factor.When reaction time increases from 4 to 15 min, the crystal structure of La1 -xSrxMnO3 formes gradually.Through analysis of kinetics model, the reaction principle of La1-xSrxMnO3 was gained by microwave synthesis and the kinetics equation was built.     

Preparation of Nanocrystalline Rare Earth Mixed Oxides DyFexCo1-xO3-δ and Its Conductivity

Nanocrystalline rare earth mixed oxides DyFexCo1-xO3-δ were prepared by sol-gel method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG-DTA) and scanning electron microscope(SEM). The results show that DyFexCo1-xO3-δ has the structure of perovskite type at 800℃ for 2 h calcination.The conductivity of the materials at different temperature was measured by four-probe instrumentation and two-pole method. The results show that the conductivity of mixed oxides DyFexCo1-xO3-δ is higher than those of un-mixed oxides DyFeO3 and DyCoO3 and the conductivity is the best at x = 0.8 in the matter of DyFexCo1-xO3-δ. The conduetivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800℃. However, the spinodals are different with different ration of Fe^3 and Co^3 . This kind of oxide is a conductive pottery material.     

钙钛矿氧化物La1-x MxCoO3-δ的电输运性能研究

采用固相反应法合成中温固体氧化物燃料电池阴极材料La1-xMxCoO3（M=Ca，Mg，Sr，x=0.2，0.4，0.6），用四探针法测试了样品在不同温度下的直流电导率和不同频率下的交流电导率。结果显示样品的直流电导率随温度的升高而增大，其电输运性能符合小极化子导电机制，具有较高的离子和电子电导率。而交流电导率的测试反映出电导是由晶界导电过程向晶粒导电过程变化的。热重分析测试表明随着温度和掺杂浓度的增加氧空位增加，氧含量减少。     

溶胶-凝胶法在纳米La1-xMxCrO3粉料制备中的应用

掺杂二价碱土金属的铬酸镧是目前研究最深入和应用效果最好的固体氧化物燃料电池(SOFC)的连接材料,它几乎占整个SOFC制造成本的一半。制备工艺有固相法、溶胶-凝胶法、化学共沉淀法、联氨法和水热法等。本文综述了溶胶-凝胶法及用该方法制备La1-xMxCrO3(M=Sr,Ca)材料的现状。     

沉淀法制备稀土氧化物纳米粉体的研究

研究了沉淀法制备稀土纳米粉体的工艺。结果表明：采用草酸作沉淀剂能够制备出球形颗粒的稀土纳米粉体，其一次粒子＜５０ｎｍ，团聚尺寸Ｄ５０＜１μｍ，比表面积＞９ｍ２／ｇ，Ｃｌ－的质量分数小于５０×１０－６，该工艺具有工业推广价值     

用SHS法合成SOFC阴极材料La1-xSrxMnO3

采用自蔓延高温合成技术（SHS）制备固体氧化物燃料电池（SOFC）阴极材料La1-xSrxMnO3（LSM）; 研究成形压力、稀释剂添加量等参数对反应过程及合成产物性能的影响; 采用XRD、ICP研究SHS法合成LSM的物相和晶型结构. 结果表明： 自蔓延高温合成产物为钙钛矿结构菱方晶系La1-xSrxMnO3, Sr含量的变化引起合成产物特征峰的位置和半峰宽变化; 随着Sr含量的增加, 合成的LSM粉末粒度变细, 晶格常数a和c减小.     

固体氧化物燃料电池阴极材料La1-xSrxMnO3的制备方法

固体氧化物燃料电池是目前最成熟、最有发展潜力的燃料电池,具有广泛的应用前景。文章综述了该电池阴极材料La1-xSrxMnO3的制备方法,比较了各种制备方法的优缺点,介绍了一种新型的制备方法—自蔓延高温合成法的研究进展。指出:自蔓延高温合成法能显著缩短阴极材料的制备周期和减少能耗,从而能降低其制造成本、促进其实用化和产业化。     

Pr_(1-x)(La_(0.37)Ce_(0.63))_xCoO_3的制备及催化活性探究

采用溶胶—凝胶法制备了Pr_(1-x)(La_(0.37)Ce_(0.63))_xCoO_3,利用TG-DSC、FT-IR分析前驱体的分解特性和化学键变化规律,结合XRD、SEM-EDS检测粉体微观结构、形貌以及元素分布;通过CV、LSV和RRDE技术探讨粉体在碱性溶液中氧还原ORR电催化活性。结果表明,在700℃下焙烧,x0.4时,有La_2O_3、CeO_2杂相出现,x0.4时钙钛矿晶体结构消失,x=0.4时得到的纯相粉体呈多孔结构。与商用Pt/C相比,Pr_(1-x)(La_(0.37)Ce_(0.63))_xCoO_3粉体质量活性(质量比电流)是其1.7倍,达到172.54mA/mg,而半波电位较低仅为0.60V(vs.RHE)。以二电子发生氧化还原反应过程中,副产物H_2O_2产率为77%,作为催化材料有待进一步改性。     

(La1-xPrx) 2/3Sr1/3CoO3 的成相过程与电导性能研究

采用固相反应法合成了(La1-xPrx) 2/3Sr1/3CoO3 (x=0.2,0.4,0.6,0.8) 双稀土氧化物系列粉体,研究了(La0.6Pr0.4) 2/3Sr1/3CoO3的成相过程和电导性能.结果表明,在实验过程中首先出现了La2O(CO3)和La2SrOx相,而La2SrOx相在270℃～910℃的较大范围内一直存在,再经过两次吸热到910℃时出现了(La0.6Pr0.4) 2/3Sr1/3CoO3 晶相,当温度达到1000℃时,(La0.6Pr0.4) 2/3Sr1/3CoO3 成为主晶相,在1250℃下烧结2h后,样品已成单一钙钛矿结构(La0.6Pr0.4) 2/3Sr1/3CoO3相.(La1-xPrx)2/3Sr1/3CoO3(x=0.2,0.4,0.6,0.8)双稀土氧化物的电导率在700℃附近时出现最大值,其中(La0.8Pr0.2) 2/3Sr1/3CoO3的电导率在中温范围内最大,适合作为中温固体氧化物燃料电池阴极材料.     

Preparation and Characterization on Nano-Sized Barium Titanate Powder Doped with Lanthanum by Sol-Gel Process

The nano-sized BaTiO3:La3 powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900 ℃ and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43.34 nm.     

溶胶-凝胶燃烧合成法制备SmBO3粉体及其性能研究

利用溶胶-凝胶燃烧合成法,在750℃热处理2 h的条件下制备了SmBO3粉体,颗粒大小在100 nm左右.红外吸收光谱显示材料在500～1400 cm-1波数范围内,存在较为集中的吸收峰.此外,由于Sm3+的6H5/2→6F9/2跃迁,使得SmBO3粉体在1.05～1.15μm的范围内反射率降低.因此,SmBO3粉体可能是一种性能较好的针对1.06和10.6μm激光的激光光防护材料和滤光功能材料.