Structure–Property Relationships in Aligned Electrospun Barium Titanate Nanofibers

Barium titanate nanofibers were uniaxially aligned by electrospinning onto a rotating copper wire drum and alignment was maintained during calcination of the fibers. Two methods for maintaining alignment during calcination were tested, by either using carbon tape or a peeling off method to remove the aligned fibers from the mandrel followed by calcination. The carbon tape removal method led to the formation of shorter aligned nanowires while the peeling off method resulted in longer nanofibers. Additionally, the effects of calcination temperature and time on crystal structure were also examined. The degree of tetragonality in the barium titanate nanofibers increased at higher calcination temperatures and times. Piezoelectricity was confirmed in the nanofibers calcined using piezoeresponse force microscopy, yielding a d₃₃ value of 15.5 pm/V. Using the methods presented here, large quantities of aligned piezoelectric barium titanate and other ceramic fibers or wires can be produced to fulfill their demand in novel microelectronics.     

Layered sodium titanate nanofiber and microsphere synthesized from peroxotitanic acid solution

In this paper, we report titania and titanate nanofiber synthesized by using peroxotitanic acid solution as a titanium source. The peroxotitanic acid solution was mixed with NaOH aqueous solution, followed by the hydrothermal treatment with or without vigorous agitation. In TEM and SEM images for solids obtained by the synthesis with vigorous agitation, nanofibers are observed. On the other hand, microspheres as well as nanofibers were observed in solids obtained by the synthesis without agitation. The microspheres are composed of nanofibers and nanosheets. EDX analysis for the obtained solids detected Ti and Na, indicating that the obtained solids are sodium titanate. As a reference, synthesis by using TiO₂ particles instead of the peroxotitanic acid solution was also performed. The Na to Ti mole ratio for the peroxotitanic acid based solid determined by EDX was 0.55 which is twice the value of 0.26 for the TiO₂ particle based solid. The obtained sodium titanate could be converted into anatase-type titania by the HCl treatment of the sodium titanate and the subsequent calcination.     

On the role of coupling agents in zirconia-polypropylene suspensions for ceramic injection molding

The effect of titanate, zirconate, and zircoaluminate coupling agents on the viscosity of zirconia-polypropylene injection molding blends was investigated. The zircoaluminate did not influence viscosity while the two former additives effected a considerable reduction. The titanate coupling agent also reduced the viscosity of the polymer in the absence of ceramic powder, and was more efficient in this respect, as a flow modifier than dioctyl phthalate. A comparable effect on the ceramic suspension was obtained by adding a species similar in molecular structure to the titanate coupling agent but without coupling ability.     

Fabrication of cadmium titanate nanofibers via electrospinning technique

Here we present an electrospinning technique for the fabrication of cadmium titanate/polyvinyl-pyrrolidone composite nanofibers. The composite nanofibers are then annealed at 600 °C to obtain ilmenite rhombohedral phase cadmium titanate nanofibers. The structure, composition, thermal stability and optical properties of as synthesized and annealed cadmium titanate nanofibers are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy. The average diameter and length of the nanofibers are found to be ～150–200 nm and ～100 μm, respectively.     

前景广阔的锌基高温脱硫剂

本文详述了以氧化锌为主的锌基高温脱硫剂（包括ＺｎＯ、ＺｎＦｅ２Ｏ４、Ｚｎ２ＴｉＯ４等），并介绍了各国在新型发电技术方面应用锌基脱硫剂的状况及我国在这方面的发展状况。     

Effects of Organotitanate Additions on the Dispersion of Aluminum Nitride in Nonpolar Solvents

Organotitanate additives are known to reduce the viscosity of many filled polymer systems, including formulations of interest for ceramic powder injection molding. Mineral oil was used as a model solvent for these systems to examine the effects of Organotitanate additions on the stability and rheology of A1N dispersions. Addition of the titanate coupling agents neoalkoxy tri(neodecanoyl) titanate and neoalkoxy tri(dioctylphosphato) titanate resulted in better dispersion as measured by sedimentation tests and rheological characterizations. Excellent correlation of the sediment heights and measured viscosities with adsorption isotherms for the organotitanates was shown, with both lower sediment height and lower viscosity obtained when a monolayer of the titanate molecules was present on the powder surface. Comparison of the behavior of the mineral oil based systems with the viscosity of corresponding polypropylene based binder systems indicates that the titanate additions are effective in reducing particle-particle interaction effects in both systems.     

Some new observations on the structural and phase evolution of nickel titanate nanofibers

In this study, we report for the first time the synthesis of nickel titanate (NTO) nanofibers containing a mixture of ilmenite and spinel phases of NTO, at an atypical low temperature. Precursor nanofibers produced by sol-gel electrospinning were calcined at three different temperatures to produce the NTO nanofibers. Thermal analysis along with X-ray photoelectron spectroscopy confirmed the formation of non-crystalline stable phases of TiN and Ti-O-N that restrained the formation of ilmenite NTO, and the Ni-rich environment pushed the Ti atoms to tetrahedral sites to form a defective spinel structure. The crystallite size of spinel NTO was observed to increase as a function of the calcination temperature above 700 °C, as the activation energy for coalescence and growth of spinel NTO was favorable. NTO nanofibers obtained above the calcination temperature of 700 °C exhibited new band gap energy around 2.5 eV in Tauc plot. Oxygen vacancies in these ceramic nanofibers decreased as the calcination temperature was increased. A hypsochromic shift of 20 nm in the photoluminescence spectra suggested that the material had a Ni²⁺ rich NTO (spinel).     

钛酸钡基电子陶瓷材料的改性进展

钛酸钡基电子陶瓷材料广泛应用于电容器、集成电路、传感器及热敏电阻等领域。高容量、小型化、抗击穿及低损耗等工业需求对钛酸钡基电子陶瓷材料的性能提出更高的要求,改性则是提高陶瓷材料性能的主要手段。综述了近年来钛酸钡基电子陶瓷材料在掺杂改性、复合改性及物理改性方面的研究进展。分析了钛酸钡基电子陶瓷材料在改性中存在的问题,比如：常规元素掺杂制备参数优化不足、稀土元素掺杂种类偏少、包覆效果待提升、聚合物陶瓷复合体综合性能欠佳、烧结工艺尚待优化等。提出了解决方法,比如：探索多种元素掺杂、优化工艺参数、改进包覆与聚合方式等。指出了钛酸钡基电子陶瓷材料的未来发展方向,即：强化烧结过程中晶粒尺寸、晶体形状、组分调控的机理研究,选取更多稀土元素进行改性,探索包覆掺杂改性、聚合物复合改性等新工艺。     

低温烧结BaTiO3基介电陶瓷的研究进展

低温烧结钛酸钡基陶瓷材料,有利于适应MLCC和LTCC的发展要求,并且降低能耗。本文综述了钛酸钡基陶瓷低温烧结方面的研究进展,包括各种低温烧结方法、机理和研究现状,着重介绍了助烧剂的作用机理,最后展望了钛酸钡基陶瓷低温烧结的发展趋势。     

Synthesis and morphology optimization of electrospun SiBNC nanofibers

SiBNC nanofibers were synthesized through the polymeric route by a one-pot synthesis approach. DMTA (dichloroboryl methyl trichlorosilyl amine) polymer was selected as pre-ceramic for SiBNC, which was shaped into nanofibers by electrospinning. Then, the nanofibers were cured in an inert atmosphere in order to obtain the final ceramic. By changing the curing atmosphere, the compound of final ceramic has been manipulated. In addition, the ceramic yield of DMTA as a preceramic was increased in the nitrogen atmosphere. The effects of applied voltage, solution concentration, and feeding rate on the morphology of final electrospun ceramic nanofibers were also investigated. Final ceramic remains amorphous up to elevated temperatures with outstanding mechanical and thermal properties.     

钛酸铅微晶玻璃介电性能研究

主要对钛酸铅系铁电性微晶玻璃的介电性能做了研究,研制的微晶玻璃初始组成由形成主晶相的氧化物和形成玻璃相的氧化物构成,经过熔融、热处理可以得到以钛酸铅为主晶相的微晶玻璃,分析了不同组成情况下微晶玻璃的介电性能.     

氧化锌晶须表面改性及表征

采用湿法表面化学改性法，用硅烷和钛酸酯偶联剂对氧化锌晶须(ZnOw)进行了表面改性；考察了溶剂、pH值、温度及分散时间对硅烷类偶联剂改性效果的影响，采用活化指数、接触角以及傅立叶变换红外光谱对改性结果作了表征。同时将改性后的ZnOw填充到线性低密度聚乙烯(LLDPE)中，测试了复合材料的机械性能。实验结果表明，硅烷和钛酸酯偶联剂均能用于ZnOw的表面改性，其最佳改性条件不同，获得最佳改性效果的偶联剂用量也不同。经ND-42改性的ZnOw填充到LLDPE中，复合材料的弯曲强度大幅度提高。     

Electrospinning: A Simple and Versatile Technique for Producing Ceramic Nanofibers and Nanotubes

Electrospinning is a remarkably simple method for generating nanofibers of polymers. When combined with conventional sol–gel processing, it provides a versatile technique for producing ceramic nanofibers with either a solid, porous, or hollow structure. This article presents a brief overview of recent progress in preparation of ceramic nanofibers by electrospinning, with a focus on an introduction to experimental procedures and analysis of several technical issues that are vital for a successful electrospinning experiment. We also highlight the unique capabilities of this technique in processing ceramic materials into nanostructures, and illustrate some potential applications of these nanostructures.     

Domain switchings within BaTiO3 nanofibers under different polarizing voltages and loading forces

We reported scanned probe characterization of the domain switching in Barium titanate (BaTiO₃) nanofibers using piezoresponse force microscopy (PFM). The PFM phase images of BaTiO₃ nanofibers under different DC polarizing voltages illustrate that domain switchings are influenced by grain boundaries and internal field. Furthermore, the amplitude–voltage butterfly loop and the phase–voltage hysteresis loop were obtained to confirm the ferroelectric character of BaTiO₃ nanofibers. With the increase of the loading forces, the nanofiber becomes brighter, which indicates that the polarization has the trend of switching to horizontal direction.     

Controlling the Diameter of Electrospun Yttria‐Stabilized Zirconia Nanofibers

This work reports the precise diameter control of electrospun yttria‐stabilized zirconia (YSZ) nanofibers from 200 to 900 nm after calcination. Fabricated YSZ nanofibers showed porous nanocrystalline structures with high aspect ratios of more than 500:1 and high surface‐to‐volume ratios with a specific surface area of 43.32 m²/g. The diameter of the YSZ nanofibers increased with the viscosity of the precursor solution, which was controlled by the concentrations of either polymers (polyacrylonitrile) or ceramic precursors (YSZ). We present a modified correlation between the diameter of a nanofiber and the synthetic conditions, as the observed behavior for calcined ceramic nanofibers deviated from the expected behavior. Our results demonstrate a modified but simple approach to fabricate ceramic nanofibers with desired diameters, providing a new design guideline for many electrochemical applications.     

Diameter control of ultrathin zinc oxide nanofibers synthesized by electrospinning

Electrospinning is a versatile technique, which can be used to generate nanofibers from a rich variety of materials. We investigate the variation of a zinc oxide (ZnO)-polyvinylpyrrolidone (PVP) composite structure in morphology by electrospinning from a series of mixture solutions of ZnO sol–gel and PVP. Calcination conditions for the crystallization of ZnO nanofibers and removal of the PVP component from the ZnO-PVP composite nanofibers were also studied. The progression of the ZnO-PVP composite structure from grains to nanofibers was observed, and ZnO-PVP nanofibers as thin as 29.9 ± 0.8 nm on average were successfully fabricated. The size of the resultant ZnO-PVP composite nanofibers was considerably affected by two parameters: the concentrations of zinc acetate and PVP in the precursor solution. The concentration of zinc acetate particularly influenced the diameter distribution of the ZnO-PVP nanofibers. The ZnO-PVP nanofibers could be subsequently converted into ZnO nanofibers of a pure wurtzite phase via calcination in air at 500°C for 2 h.     

基于静电纺丝技术制备Cu2+掺杂TiO2纳米纤维的研究

以聚苯乙烯溶液为络合剂与钛酸丁脂/醋酸铜混合制得前驱体,采用静电纺丝法制得聚苯乙烯(PS)/钛酸丁脂[Ti(OC4H9)4]/醋酸铜[Cu(CH3COO)2·H2O]复合纤维,经焙烧后得到均一直径、具有较高比表面积和多孔结构的TiO2/CuO复合纳米纤维.对所制得的纳米纤维的结晶度、表面形貌,分别采用X射线粉末衍射、红外光谱( IR) 、扫描电镜(SEM) 等分析测试手段进行了表征.结果表明,煅烧温度、PS浓度、钛酸丁脂浓度对纤维的直径和形貌有很大影响.     

TiO2纳米纤维的电纺制备与表征

以PVP作为络合剂与Ti（C4H9O）4反应制得前驱体,采用静电纺丝法制得PVP／TiO2纳米复合纤维后在马弗炉中煅烧,并采用SEM、TG—DTA、XRD等对纳米纤维进行了表征。结果表明：适当增加Ti（C4H9O）4浓度、增加静电电压、减小喷射速度和升高煅烧温度,电纺丝纤维直径变细;PVP／TiO2复合纤维煅烧至550℃时得到的为纯TiO2;经400℃、600℃、700％、900％煅烧后分别得到开始出现锐钛矿型的TiO2、以锐钛矿型的TiO2为主、以金红石型的TiO2为主和完全金红石晶型的TiO2纳米纤维。     

Preparation and characterization of alumina submicron fibers by plasma assisted calcination

Ceramic alumina nanofibers were prepared by plasma-assisted calcination (PAC) using atmospheric pressure plasma. Electrospun polyvinyl pyrrolidone/aluminium butoxide fibers were pre-treated by plasma generated in ambient air using a special type of coplanar dielectric barrier discharge. The effect of plasma on fibers and structural, chemical and crystalline properties of obtained ceramic nanofibers were characterized using X-Ray Photoelectron Spectroscopy and Scanning Electron Microscopy, Energy-dispersive X-ray Spectroscopy and X-Ray Diffraction. Thermogravimetric and differential thermal analysis were used for the study of thermal behaviour of untreated and plasma-treated samples. The ceramic fibers prepared by PAC exhibit suitable chemical composition, higher porosity, high length of fibers and better crystalline properties with simultaneous simplifying of the sintering process. The plasma pre-treatment of fibers results in a shortening of following thermal treatment, decrease of the required temperature and excludes a slow temperature increase as prevention of fibrous structure degradation typical in preparation of ceramic fibers by polymer-template techniques.     

纳米钛酸钡的掺杂对陶瓷性能的影响

采用掺杂纳米级钛酸钡和碳酸锰的方法,观察了掺杂不同量纳米级钛酸钡和碳酸锰后的钛酸钡坯片烧结所得陶瓷表面的显微组织形貌的变化,研究了单一掺杂纳米级钛酸钡、单一掺杂碳酸锰、复合掺杂碳酸锰+纳米级钛酸钡对陶瓷制品晶粒尺寸与介电性能的影响。结果表明：掺杂纳米级钛酸钡对钛酸钡陶瓷制品的介电性能有显著的提升,但是随着掺杂量的进一步增加,其介电性能的变化不大;掺杂碳酸锰对钛酸钡陶瓷晶粒的细化效果优于掺杂纳米级钛酸钡的效果;复合掺杂1%（质量分数,下同）碳酸锰+1%纳米级钛酸钡所得陶瓷的致密性高于单一掺杂1%碳酸锰的效果。