溶胶-凝胶法制备的钛酸钡薄膜光学性质的影响因素概述

铁电体具有反常光生伏打效应,是一类极具发展潜力的新型太阳能电池材料和光电敏感材料。钛酸钡是最为典型的一种铁电材料,为将它用作太阳能电池和光电敏感材料,国内外对它的光学性质进行了广泛研究。综述了溶胶凝胶制备条件、膜厚、掺杂与钛酸钡铁电薄膜光学性质的关系,并提出了研究中亟待解决的问题。     

纳米钛酸钡的制备及组织与性能分析

采用溶胶-水解法制备了纳米级的钛酸钡粉体,并对其进行了压片和高温烧结,研究了钛酸钡粉体的结构特征和纳米钛酸钡压片的微观结构和介电性能。结果表明,在制备钛酸钡过程中,调整p H值可以改变粉体的晶相结构;提高钛酸钡的烧结温度,可以提高钛酸钡陶瓷的致密性,使钛酸钡陶瓷的介电常数上升。     

电场诱导沉积方法制备PLZT基单层有序周期结构多孔薄膜

利用电泳组装聚苯乙烯微球单层模板为基础,以溶胶-凝胶方法制备含有纳米粒子的母液,通过电场诱导母液中纳米粒子填充模板孔隙,制备具有反演结构的PLZT有序多孔薄膜.通过SEM和XRD分析,分别给出通过电场诱导PLZT凝胶中纳米粒子沉积得到了单层有序周期结构的微观结构形貌及晶相组成.提供一种简单的制备而为铁电有序微结构的方法,可以用于功能陶瓷基光子带隙材料的研究.     

溶胶-凝胶法制备有机硅/SiO2杂化材料的研究进展

介绍了溶胶-凝胶法制备有机硅/SiO2杂化材料的原理与工艺,综述了有机硅/SiO2杂化材料在耐热材料、腐蚀防护材料、光学材料领域的应用研究情况.使用溶胶-凝胶法制备的有机硅/SiO2杂化材料作为一种全硅体系,很好地结合了有机硅和纳米SiO2的优势,具有很好的发展前景.     

准一维铁镍合金材料的制备研究进展及应用展望

综述准一维铁镍合金材料(纳米棒、纳米线、纳米管、纳米纤维、纳米须)的各种制备方法和应用现状,主要介绍模板法、磁场引导羰基热分解法、还原法、微波等离子体法、溶胶-凝胶-热分解还原法、配位共沉淀-热分解法等,比较了各种制备方法的优缺点,介绍了其在相关领域的应用现状,最后展望其制备和应用的发展趋势。     

纯钛表面制备钛酸钡薄膜的技术参数研究

目的 探讨在纯钛基片上制备钛酸钡薄膜的技术参数,为增强钛瓷结合强度奠定研究基础。 方法 以碳酸钡和钛酸丁酯为原料,利用溶胶-凝胶法在纯钛基片上制备钛酸钡薄膜,对比不同浓度溶胶、不同干燥机制条件下制备的薄膜的质量。 结果 180 ℃ 干燥、380 ℃ 热处理、升温速率 6 ℃ / min 和 120℃ 干燥、300 ℃ 热处理、升温速率 3 ℃ / min 两种条件相比,前一种条件制备的薄膜退火后开裂程度大。 采用 0 . 3 mol / L 钛酸钡溶胶,在后一种条件下制备的薄膜基本完好,无裂纹;而采用 0 . 35 mol / L 钛酸钡溶胶,在相同条件下制备的薄膜裂纹较明显。 结论 采用 0 . 3 mol / L 钛酸钡溶胶,在 120 ℃ 干燥、300 ℃ 热处理、升温速率 3 ℃ / min 的条件下制备薄膜,薄膜质量最佳。     

不同方法制备的ODSRAFM钢的结构和性能比较

比较了机械合金化法、溶胶-凝胶-等离子体烧结法和真空熔炼法三种方法制备的氧化物弥散强化低活化铁素体/马氏体钢的结构和性能。机械合金化方法和溶胶-凝胶-等离子体烧结法制备得到的材料氧化物粒子达到纳米级;真空熔炼方法可制备出微米级大小的氧化物弥散强化材料。上述方法制备的材料强度均得到改进。     

PZT压电陶瓷纤维的制备及性能研究

采用溶胶-粉末混合挤出法制备Pb(zr,Ti)O3压电陶瓷纤维.研究了PZT纤维制备的合理条件,如溶胶粘度的调整,粉末和溶胶的混合比例及烧结温度等.在溶胶和粉末的摩尔比为1:7时能成功地挤出直径为500μm的纤维生坯.研究了不同烧结温度下的纤维密度、收缩率及显微结构,并将纤维与环氧复合制备1-3型复合材料,研究复合材料的介电及压电性能.结果表明,在1240℃下烧结纤维及复合材料表现出更好的性能.     

苹果酸溶胶-凝胶法制备氧化铝长纤维(英文)

用硝酸铝、苹果酸为原料,用溶胶-凝胶法制备氧化铝前驱体溶胶。研究了苹果酸、聚乙烯吡咯烷酮(PVP)的加入量对溶胶可纺性能的影响。研究发现:当硝酸铝、苹果酸、PVP的质量比为10:3:1.5时,得到的凝胶纤维长度大于80cm。用热重-差示扫描(TG-DSC)、傅里叶转换红外线光谱(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)分析方法对凝胶纤维和陶瓷纤维进行了表征。凝胶纤维的长度大于80cm。凝胶纤维在1200℃煅烧1h后,物相为α-Al2O3,得到的氧化铝纤维直径均匀、表面光滑,纤维直径为20μm。     

静电纺丝法制备钛酸钡纳米纤维的工艺研究

以乙酸钡和钛酸四丁酯为原料,以聚乙烯吡咯烷酮(PVP,Mw=1 300 000)为粘性剂,采用溶胶-凝胶法结合静电纺丝技术制备了高长/径比的钛酸钡纳米纤维(BaTiO3 NFs)。研究了乙酸-乙醇-去离子水、乙酸-N,N-二甲基甲酰胺(DMF)-去离子水和乙酸-DMF-乙酰丙酮3种纺丝溶剂对纤维直径的影响,结果表明,经900℃煅烧处理后的BaTiO3 NFs主相为立方相。当PVP含量为8.7%(质量分数,下同)时,乙酸-DMF-乙酰丙酮为优化的纺丝溶剂,此时制备的BaTiO3 NFs直径最小,为200 nm,长/径比最大,为100:1;在此基础上,又采用正交实验法,考察了针头到接收器的距离、纺丝液流率和纺丝电压等纺丝参数对BaTiO3 NFs纤维长/径比的影响,结果发现,当针头到接收器的距离为21 cm、流率为0.5 mL/h以及纺丝电压为21 kV时,制备的BaTiO3 NFs形貌较均匀,直径为200 nm,长/径比最大,为125:1。     

超细银包覆BaTiO3粉体的制备

讨论了金属-陶瓷复合材料超细银包覆BaTiO3粉体的制备条件，采用扫描电镜，激光粒度分布仪，比表面积分析仪及X射线荧光光谱仪表征了复合粉末颗粒的形貌和粉体的团聚状态。讨论了银在钛酸钡粉末表面的包覆形式。采用化学镀的方法在BaTiO3表面沉积金属银。在天然高分子表面活性剂的保护下，Ag(NH3)2^ 被水合肼还原得到分散性良好的不同含银量的复合粉体。最佳的反应条件是：银含量0．1％～0．5％，Sodium Alginate／Ag(质量比)20％，粉末中Ag含量小于80％，反应时间120min，水合肼浓度0．8％。实验表明所得颗粒是银包覆在BaTiO3表面的形成一定银层厚度的复合体系。     

Fabrication of poly-3-hexylthiophene/polyethylene oxide nanofibers using electrospinning

P3HT–PEO blend nanofibers were produced by electrospinning from chloroform solutions. A morphological study was carried out as a function of the processing parameters as well as the ratio between the two polymers. The fibers containing at least 60 wt.% of P3HT presented striated surfaces that could be explained by the alignment of the polymer domains along the fiber axis. The structural arrangement of the polymers was found to vary according to the polymers relative contents. The maximum electrical conductivity found for unaligned mats was 0.16 S/cm and increased to 0.3 S/cm when the nanofibers were aligned along a preferential direction.     

静电纺丝法合成LaMnO_3及La_(0.875)Sr_(0.125)MnO_3纳米纤维

通过静电纺丝法合成了LaMnO_3和La_0.875Sr_0.125MnO_3纳米纤维,利用X射线衍射、扫描电子显微镜和透射电子显微镜对纳米纤维进行了表征,同时阐述了静电纺丝法在合成复杂成分陶瓷纳米纤维方面的特点和优势.     

Electrospun PEDOT:PSS/PVP nanofibers as the chemiresistor in chemical vapour sensing

Herein, PEDOT:PSS/PVP nanofibers were produced by electrospinning. The presence of PEDOT:PSS in the nanofibers was confirmed by FT-Raman spectroscopy. The applied voltage-dependent diameter of PEDOT:PSS/PVP nanofibers was observed. Also, sensing behaviors of electrospun PEDOT:PSS/PVP nanofibers were explored by measuring its response upon cyclic exposure to organic vapours such as ethanol, methanol, THF, and acetone at room temperature. When PEDOT:PSS/PVP nanofibers were exposed to each solvent, the protic and aprotic solvents resulted in opposite electrical responses. These findings exhibit that electrospun PEDOT:PSS/PVP nanofibers are the promising candidate for the organic vapour sensing material.     

A study on the preparation of poly(vinyl alcohol) nanofibers containing silver nanoparticles

In this study, two practical methods for the facile and controlled preparation of poly(vinyl alcohol) (PVA) nanofibers containing Ag nanoparticles were investigated for use in antimicrobial applications. In the first method, PVA nanofibers containing Ag nanoparticles were successfully electrospun from PVA/silver nitrate (AgNO₃) aqueous solutions after first refluxing them. The Ag nanoparticles in the PVA/AgNO₃ aqueous solutions were generated by refluxing them. Interestingly, it was found that the Ag nanoparticles were also spontaneously generated during the electrospinning process. In the second method, Ag nanoparticles were generated by annealing the PVA nanofibers electrospun from PVA/AgNO₃ aqueous solutions. Residual Ag⁺ ions and the Ag nanoparticles generated during the electrospinning process in the PVA nanofibers were diffused and aggregated into larger Ag nanoparticles during the annealing process. All of the Ag nanoparticles were sphere shaped and evenly distributed in the PVA nanofibers prepared by the two methods.     

La2O3纳米纤维的制备及抗菌性能研究

采用静电纺丝法制备了氧化镧纳米纤维,并通过X射线衍射(XRD),X射线光电子能谱(XPS),扫描电子显微镜(SEM),透射电子显微镜(TEM)以及比表面积分析仪(BET)分析了物相结构和显微形貌。探究了氧化镧纳米纤维的抗菌性能和机理。结果表明,静电纺丝法可成功制得高长/径比,直径均匀且连续的氧化镧纳米纤维。该纤维在负载量极低(200 mg/L)的情况下,对高浓度革兰氏阴性大肠杆菌(10~7 CFU/L)具有超快速灭菌效果,可在100 min内达到95%以上的细菌灭活率。通过长时间的培养和观察表明,该纤维具有彻底且长效的抑菌效果,长时间培养后未观察到细菌的反复增殖。此外,氧化镧纳米纤维对鲍曼不动杆菌和绿脓杆菌也具有良好的灭菌效果,是一种潜在的广谱抗菌材料。     

电纺法制备PAN基高比表面积活性纳米碳纤维

将聚丙烯腈(PAN)粉末配制为PAN/DMF溶液,通过静电纺丝工艺制备了PAN纳米纤维,然后依次进行预氧化、碳化处理得到纳米碳纤维;采用CO₂作为活化剂制备了超大比表面积活性碳纤维。使用扫描电镜、场发射透射电镜、拉曼光谱,傅里叶红外光谱和N₂吸附等手段对样品的形貌、成分和结构进行了全面表征,研究了聚合物溶液浓度和静电压对PAN纳米纤维形貌和直径的影响。活性碳纤维独特的孔结构使其作为电极材料在多种电解液中保持了较高的比容量。结果表明活化后的碳纤维的比表面积、总孔容和微孔孔容都明显增加,本研究所制备的活性碳纤维具有极高的比面积和良好的电导率,使其在超级电容器电极材料领域有着进一步的应用。     

Electrospun poly(vinyl alcohol) nanofibers incorporating PEGylated multi-wall carbon nanotube

Recently, the fabrication of polymer composite nanofibers containing multi-wall carbon nanotube (MWCNT) by electrospinning has attracted much attention due to their potential advantages for the enhancement of properties such as electrical and thermal conductivity. In order to utilize the superior properties of MWCNT, in this study, MWCNT was covalently grafted with poly(ethylene glycol) (PEG) chains and PEGylated MWCNT-incorporated PVA nanofibers were prepared by electrospinning. To do so, MWCNT was firstly chemically oxidized to bear carboxyl groups and successively reacted with PEG molecules in ethanol. The PEGylated MWCNT was mixed with aqueous PVA solution and electrospinning was performed. The degree of surface modification of MWCNT by PEG was thoroughly investigated by FT-IR, XPS and TGA. Compared to the pristine MWCNT, the PEGylated MWCNT was uniformly dispersed PVA nanofibers without agglomeration. Because of the enhanced dispersion of PEGylated MWCNT in PVA nanofibers, the electrical conductivity of nanofibers with PEGylated MWCNT (1.0 wt%) was increased by 4 orders of magnitude compared to that of nanofibers with pristine MWCNT (1.0 wt%).     

静电纺丝技术制备NiFe_2O_4纳米纤维的表征

采用溶胶-凝胶法与静电纺丝技术相结合制备了PVP/[Ni(NO3)2+Fe(NO3)3]复合纳米纤维,在一定温度下进行热处理,得到尖晶石结构的NiFe2O4纳米纤维。利用TG-DTA、XRD、FTIR、SEM、TEM等分析手段对样品的组成及结构进行表征。TG-DTA分析表明,PVP/[Ni(NO3)2+Fe(NO3)3]复合纳米纤维的热处理温度高于450℃以后,质量恒定,总失重率为87.8%。XRD与FTIR分析表明,热处理温度高于600℃时,复合纳米纤维已经完全转变成尖晶石结构的NiFe2O4纳米纤维。SEM分析表明,所制备的PVP/[Ni(NO3)2+Fe(NO3)3]复合纤维直径在250～300nm之间,NiFe2O4纳米纤维直径约100nm,长度大于200μm。对NiFe2O4纳米纤维的形成机理进行了探讨。     

Fabrication and electromagnetic properties of fe nanofibers composites

In order to develop electromagnetic (EM) wave absorbing materials in the giga-hertz (GHz) frequency range, Fe nanofibers have been prepared by multi-nozzle electrospinning process (ESP) and heat treatments. The effects of applied voltage and feed rate on the morphology of electrospun PVP/Fe salt nanofibers have been studied in the electrospinning process. The average diameter and the standard deviation of electrospun nanofibers tend to decrease with the increase of the applied voltage and the decrease of the feed rate, respectively. Through the heat treatments of calcination and H₂ reduction, as-spun PVP/Fe salt has been stepwise transformed into Fe₂O₃, Fe₃O₄, and Fe phases. To evaluate the EM characteristic of the prepared Fe nanofibers, epoxy matrix composites containing Fe nanofibers of 10 and 30 wt% have been fabricated. The Fe nanofibers have improved the EM characteristics of composites as compared to those of nano-sized metallic particles.