Ta2O5/Nb2O5粉末摇实密度的测定

采用一种特制的摇实装置,对Ta2Os/Nb2O5粉末的摇实密度进行测定.用该装置摇实Ta2O5/Nb2O5直到其体 积不再进一步减小,然后用Ta2O5/Nb2O5粉末的质量比摇实体积即可得到Ta2O5/Nb2O5的摇实密度.     

Preparation, characterization and photocatalytic behavior of WO3-TiO2/Nb2O5 catalysts

TiO2/Nb2O5 photocatalyst loaded with WO3 (WO3-TiO2/Nb2O5) was prepared by a modified hydrolysis process, and characterized by X-ray diffractometry, transmission electron microscopy, Raman spectra and UV-Vis diffuse refraction spectroscopy. The photocatalytic activity of WO3-TiO2/Nb2O5 was investigated by employing splitting of water for O2 evolution. The results indicate that WO3 loading can pronouncedly improve the photocatalytic activity of TiO2/Nb2O5 by using Fe3 as an electron acceptor under UV irradiation. The optimum molar fraction of the loaded WO3 is 2%, and the largest speed of O2 evolution for 2% WO3-TiO2/Nb2O5 catalyst is 151.8 μmol/(L·h).     

离子辅助沉积对 Nb2O5薄膜特性的影响

为了提高Nb2O5薄膜的聚集密度,改善氧化铌薄膜的光学特性和机械特性,采用霍尔源离子辅助沉积(IDA)技术在K9玻璃基板上制备了Nb2O5单层薄膜,并与常规沉积条件下制备的Nb2O5薄膜作了比较.由于IAD技术使Nb2O5膜的聚集密度提高了14%,膜层折射率从常规工艺的2.03上升到2.18,膜层的附着力和牢固度从常规工艺的1.0×107N/m2提高到129.7×107N/m2.     

A new sol-gel process for preparing Ba（Mg1／3Nb2／3）O3 nanopowders

Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2·4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders. At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na ions. The as-prepared colloidal Nb2O5·nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1 h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.     

LiNi0.6Co0.1Mn0.3O2材料的制备及其Nb2O5包覆改性

高镍层状LiNixCoyMn1-x-yO2（x≥0.6）三元材料具有较高的能量密度,但因锂镍混排、结构稳定性不佳等问题限制了其在锂离子电池中的应用。因此,采用Nb2O5包覆对三元材料LiNi0.6Co0.1Mn0.3O2（NCM613）进行改性,并考察了不同包覆量对NCM613的形貌结构和电化学性能的影响,得出了最佳工艺条件的包覆量为0.75%。首先,采用共沉淀法制备了前驱体Ni0.6Co0.1Mn0.3(OH)2;然后利用高温固相法制备了裸样LiNi0.6Co0.1Mn0.3O2（NCM613）;最后加入不同物质的量的Nb2O5粉末,通过球磨后高温烧结回火法制备了不同比例包覆量的Nb2O5@NCM613样品。XRD分析结果表明,各包覆样品与裸样NCM613的晶体结构相似,都具有完整的α-NaFeO2层状结构,阳离子混排程度较低;SEM分析结果表明,包覆样品和裸样NCM613均为1.0~1.5 μm的类球状粒子,且Ni、Co、Mn和Nb元素均匀分布在类球状材料表面;TEM分析结果表明,0.75Nb2O5@NCM613样品的Nb2O5包覆层厚度约为10~20 nm;材料电化学性能研究结果表明,在2.7~4.3 V、0.2C的电流密度条件下NCM613和0.75Nb2O5@NCM613的首圈放电比容量分别为208.11, 237.39 mA·h/g,1.0C循环100圈后,0.75Nb2O5@NCM613的放电比容量为176.43 mA·h/g,容量保持率高达86%。与裸样相比,在100圈循环后0.75Nb2O5@NCM613的阻抗明显降低,电化学极化降低,可逆性增强,这是因为Nb2O5包覆能提高材料的结构稳定性和电化学性能。可见,Nb2O5包覆高镍三元材料有利于推动高镍层状正极材料的工业化生产。     

介孔分子筛Nb2O5/SBA-15催化合成油酸甲酯

以介孔分子筛SBA-15为载体,采用浸渍法合成了Nb2O5/SBA-15催化剂。通过XRD、BET等测试手段对样品进行了分析。结果表明,负载Nb2O5的SBA-15分子筛具有高度有序的二维六方介孔结构,并且具有较大的比表面积、孔容和孔径。Nb2O5/SBA-15分子筛催化剂的酯化反应最佳反应条件为：醇酸物质的量比为2∶1,反应温度160 ℃ ,反应时间4 h,催化剂用量为原料总质量的9.10%。Nb2O5/SBA-15催化剂具有较好的稳定使用性,是一种合成油酸甲酯的理想固体酸催化剂。     

熔融淬冷法制备V2O5干凝胶薄膜的XPS研究

研究在熔融淬冷法中应用氧气顶吹工艺制备了 V2 O5溶胶。XRD分析表明 ,氧气顶吹工艺制备的 V2 O5· n H2 O凝胶薄膜与空气中熔融 V2 O5制备的 V2 O5· n H2 O凝胶薄膜的结构有细微差别。着重采用 X射线光电子能谱 (XPS)分析了两种 V2 O5干凝胶薄膜的化学组成及钒、氧离子的化学状态     

“绣球”状中空C/Nb2O5微球的制备及其 电化学性能研究

以草酸铌为铌源,空心碳球为模板,采用简单的水热法合成了具有独特形貌的“绣球”状中空C/Nb2O5微球。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）表征了所制备中空C/Nb2O5微球的微观结构,并采用电化学工作站研究了其作为负极材料的锂离子电池的电化学性能。研究结果表明,直径约为1 μm的空心碳球被Nb2O5包覆,中空C/Nb2O5微球呈现出独特的“绣球”形状,使其比表面积明显增大;在电流密度为40 mA/g下,中空C/Nb2O5微球和Nb2O5微球作为负极材料的锂离子电池的初始放电比容量分别为402.26 mA·h/g和336.44 mA·h/g,经过50次充放电循环后,当电流密度返回40 mA/g时,中空C/Nb2O5微球的放电容量为192.38 mA·h/g,而Nb2O5微球的放电容量仅为4.86 mA·h/g。说明这种特殊的“绣球”状中空结构有效地增加了Nb2O5的表面积,并使得中空C/Nb2O5微球负极材料具有高的比容量和良好的可逆性能。     

氧化铝涂层在熔融锌液中的腐蚀及热震行为

为了分析陶瓷涂层的失效机制,将带有陶瓷涂层的试件放入到锌液中进行腐蚀,并与热震后的涂层试件进行比较.通过电镜照片的微观分析及x 射线衍射分析得出,腐蚀后涂层与锌液界面处生成了锌铝氧三元化合物ZnO.Al₂O₃、3ZnO.47Al₂O₃、4ZnO.11Al₂O₃等,热震后的试件则出现涂层开裂及脱落现象.对比腐蚀试验和热震试验说明,陶瓷涂层在锌液中腐蚀不足以使涂层发生失效,而热震后发生涂层开裂进而使锌液进入涂层内部直接与基体接触会造成涂层失效     

Molten Salt Synthesis of Ba（ Mgl／3Nb2／3 ）O3 Powder

The single-phrase Ba(Mgl/3Nb2/3)O3(BMN) powder was saccessfully prepared by the KCImolten salt synthesis(MSS) method. The temperature for single-phase BMN powders by MSS was about 400℃ lower than that by the solid-phase method. The average particle size (APS) was about 0.91,u.m at 900℃ and increased with increasing synhesis temperature. Based on the APS, the activation energy for particle growth in theMSS, whose value was 64. 1kJmol^-1.was attained. The sinterability of the powder prepared by MSS method wasbetter than that pretared by solid-phase method.     

白云鄂博铌精矿碳还原直接合金化热力学研究

本文针对使用铌精矿代替铌铁合金在精炼炉的环境下进行直接合金化炼钢的过程,使用FactSage软件进行还原剂为C时,不同Nb2O5活度系数、温度、碱度、渣成分下[Nb]/Nb2O5值进行热力学平衡计算.综合分析结果表明,Nb2O5活度系数成为影响其还原进入钢液的重要因素之一;C作为还原剂时的有利条件为高温、低碱度、低（FeO）;（TiO2）对于[Nb]/Nb2O5的影响较小.使用《矿物炼钢》中类似体系的共存模型结果计算了C还原Nb2O5反应的吉布斯自由能随温度和碱度的变化.结果表明C还原Nb2O5反应的AG随碱度升高而增大,随温度的升高而降低.LNb随碱度升高而降低,随温度的升高而升高.     

Structure and Dielectric Properties of ZnO and Nb2O5 Doped BaO-TiO2 System Microwave Ceramics

The microwave dielectric properties and microstructure of BaTi4.3ZnyO9.6 y 0.02 mol% SnO2 0.01 mol% MnCO3 x mol% Nb2O5(x=0-0.05, y=0-0.08) system ceramics were studied as a function of the amount of ZnO and Nb2O5 doped. Addition of (y=0-0.05) ZnO and (x=0-0.025) Nb2O5 enhanced the reactivity and decreased the sintering temperature effectively. It also increased the dielectric constant εr and quality factor Q(=1/tan δ) of the system due to the substitution of Ti4 ions with incorporating Zn2 and Nb5 ions, which was analyzed by the reaction ZnO Nb2O5 3 TiTiX→ZnTi 2NbTi 3TiO2. When the system doped with (y=0.05) ZnO and (x=0.025) Nb2O5 were sintered at 1 160 ℃ for 6 h, the εr, Qfo value and τf were 36.5, 42 000 GHz, and 1.8 ppm/℃, respectively, at 5 GHz.     

钢包渣中的氧化物与氮反应的热力学研究(二)

通过对钢包渣中V2O5,Nb2O5,La2O3等氧化物与氮反应的理论计算可知:在低压下,向还原性钢包渣中添加氧化物(V2O5,Nb2O5,La2O3),这些氧化物都可以与钢液中氮反应,对钢液脱氮有利;其中V2O5对钢液脱氮的促进作用明显大于其它两种氧化物;钢液在深脱氧的情况下,熔渣中这些氧化物都促进钢液脱氮.     

Morphological evolution of Nb2O5 in a solvothermal reaction: From Nb2O5 grains to Nb2O5 nanorods and hexagonal Nb2O5 nanoplatelets

Novel Nb₂O₅ nanorods and polygonal Nb₂O₅ platelets were generated by a simple solvothermal technique. The geometry evolution of the resultant Nb₂O₅ from amorphous nanoparticles to crystallized particles, from polygonal platelets to well-elongated nanorods was been studied in detail. The processing parameters, including the reaction temperature, reaction time, concentration of the precursors, and pH value of the solution, which affect the shape and size of the nanorods, were investigated. The Nb₂O₅ nanorods with different aspect ratios were examined by XRD, SEM and TEM. The experimental results show that Nb₂O₅ nanorod is the orthorhombic structure and well-crystallized. The growth of the nanorods follows their [001] direction. The successful generation of high quality Nb₂O₅ nanorods is not only important for transition metal oxide research, but also potentially important for further formation of new Nb-based 1-D nanostructures, such as NbS₂ and NbN. Funded by the International Cooperation Project of Hubei Province (2006 CA014)     

Ba1+x(Mg1/3Nb2/3)O3 陶瓷的烧结行为和微波介电性能

研究了A位Ba离子化学计量比变化对Ba(Mg1/3Nb2/3)O3陶瓷烧结行为、微观结构和微波介电性能的影响.结果表明,Ba缺量可促进Ba(Mg1/3Nb2/3)O3烧结和B位1∶2有序,而Ba过量则阻碍Ba(Mg1/3Nb2/3)O3烧结和B位1∶2有序.Ba缺量促进Ba(Mg1/3Nb2/3)O3烧结和B位1∶2有序是由于Ba缺位的存在,而Ba过量阻碍Ba(Mg1/3Nb2/3)O3烧结则是由于过量的Ba可能以游离态存在于晶界,阻碍了晶界的移动,从而降低了Ba(Mg1/3Nb2/3)O3陶瓷的烧结性能,抑制了致密化过程.Ba缺量对Ba(Mg1/3Nb2/3)O3陶瓷的介电常数影响不大.Ba缺量越多,材料的Qf值越低.     

The structure and properties of Ag(Nb0.8Ta0.2)O3 ceramic doped with MnNb2O6

The influences of doping of MnNb2O6 on the structure and dielectric properties of Ag(Nb0.8Ta0.2)O3 were illustrated. Ag(Nb0.8Ta0.2)O3 samples doped with different amount of preformed MnNb2O6 (1 mol%, 2 mol%, 3 mol%, 4 mol%, 6 mol%, 8 mol%) were prepared by traditional solid-state reaction method and characterized by XRD, SEM and EDS, and the dielectric properties of samples were compared. The experiment results indicated that when the doping amount of MnNb2O6 was greater than 3 mol%, second phase appeared because of the solid solution limit. The permittivity of the Ag(Nb0.8Ta0.2)O3 samples doped with MnNb2O6 firstly increased and then decreased with the sintering temperature, while the dielectric loss decreased first, and then increased slightly. 1 100 ℃ seems to be the most proper sintering temperature for most of the samples. When the amount of MnNb2O6 is about 3 mol%, the samples have the best dielectric properties, larger permittivity and smaller dielectric loss.     

BiFeO3-SrBi2Nb2O9铁电陶瓷的结构及性质

用高能振动技术制备了单相层状结构的BiFeO3-SrBiNb2O9的铁电陶瓷，研究了BiFeO3的掺杂对SrBi2Nb2O9微观结构和介电性能的影响，分析了陶瓷的介电性质．