PID调节器对制备纳米钛薄膜的重要作用

简述了IBAD(离子束辅助沉积)法制备纳米钛膜的过程中,关键工艺因素是如何将衬底温度维持在一个适当的范围,并运用PID(比例积分微分)调节器较好地实现这一要求的。

镀覆碳基纳米薄膜钛合金的体外抑菌性能初步评价

背景:应用镀覆碳基纳米薄膜钛合金材料制作的人工髋关节球头产品拟开始临床试验,但该材料的抑菌性能尚不清楚。目的:研究镀覆碳基纳米薄膜钛合金的体外抑菌性能。方法:将镀覆碳基纳米薄膜钛合金与人工关节常用的钴铬钼合金制成相同规格的圆片状试件。通过与金黄色葡萄球菌、大肠杆菌标准菌株共同培养。从抑菌圈大小、扫描电镜观察、荧光染色、菌落形成单位计数等方法评价其抑菌性能。结果:金黄色葡萄球菌和大肠杆菌分别与镀覆碳基纳米薄膜钛合金和钴铬钼合金共培养,均未能形成明显抑菌圈。但钴铬钼合金表面可见部分生物膜。通过扫描电镜和荧光染色技术可以观察到新型镀膜钛合金黏附细菌更少。同时菌落形成单位计数也表明镀覆碳基纳米薄膜钛合金黏附细菌相较钴铬钼合金少。结论:新型镀覆碳基纳米薄膜钛合金较钴铬钼合金抑菌性能更强。

铈掺杂对氧化钛薄膜光吸收性能的影响

采用电子束蒸发法制备铈掺杂的TiO2薄膜,研究掺杂铈TiO2薄膜的透过率,以及掺杂对TiO2薄膜光吸收性能的影响。实验发现掺杂CeO2使氧化钛薄膜的禁带宽度Eg从3.27eV减小到2.51eV,从而使光学吸收边从380nm红移到495nm,大大提高了对太阳光或可见光的利用能力。

碳/钛复合薄膜结构二次电子发射规律

随着我国航天事业的发展,航天器中搭载的微波部件趋于小型化、集成化,而由此带来的微放电效应愈发显著,如何有效抑制微放电效应已成为当前研究的热点。文章使用磁控溅射技术制备了不同掺杂比例的钛/碳复合薄膜。对薄膜样品进行形貌、拉曼光谱及二次电子发射特性的测试分析。结果表明:随着金属钛掺杂比例的提高,薄膜按照柱状结构生长的规律越明显,致密度和平整度越好。结合测试结果及相关理论分析薄膜作用的机理,在碳/钛原子比为0.764时,复合薄膜的最大二次电子发射系数为1.40。碳/钛纳米复合薄膜对微放电效应具有良好的抑制效果,且具有大面积制备及工艺简单等特点。有助于未来有效载荷系统向高功率、高频段、集成化的方向发展。

掺钛氧化锌纳米薄膜的研究进展

在论述磁控溅射制备的掺钛氧化锌薄膜研究意义的基础上,介绍了目前国内外有关采用磁控溅射制备的掺钛氧化锌薄膜的研究现状,并展望了掺钛氧化锌薄膜的未来研究方向。

光响应型钛基纳米薄膜的制备及防腐性能研究

基于企业生产研究背景与优势,提出利用廉价且易得的钛源(例如:TiOSO4)材料为原料,采用反应简单、操作便捷的sol-gel法在基材表面制备一层或多层纳米级钛基薄膜,研究镀膜后基材在紫外光光照和暗态条件下的耐腐蚀能力,意图通过镀膜大幅度提高基材的耐腐蚀能力。通过选择钛源、沉淀剂、水溶胶的钛浓度、络合剂比例和反应温度优化水溶胶制备工艺;同时研究不同浓度水溶胶的粘温特性及采用水溶胶浓缩为干凝胶的方法对水溶胶中颗粒粒径和形貌进行观测,溶胶粒径均小于50 nm。后期采用匀速提拉法在基板表面进行不同层数薄膜的制备,采用相应热处理得到纳米钛基薄膜,并研究纳米薄膜的形貌。最后将基片制作成电极浸渍在3.5%氯化钠溶液中测试其防腐性能,制备纳米薄膜表面颗粒粒径均小于50 nm,五层膜厚度在1μm左右。防腐性能测试结果表明在基材表面制备防腐薄膜提高了基材腐蚀电位、降低其腐蚀电流,在暗态条件下,相较基板的防护效率最高可达99.73%;在紫外光照下,相较基板的防护效率最高可达99.14%。同时通过暗态和紫外光照下的基板的开路电位分析,在紫外光照射下相对于暗态下的开路电位出现不同程度负移的情况,展现出薄膜具有光响应性。

Self-Organizing Evolution of Anodized Oxide Films on Ti-25Nb-3Mo-2Sn-3Zr Alloy and Hydrophilicity

In the present work,hierarchical nanostructured titanium dioxide(TiO2) films were fabricated on Ti-25Nb-3Mo-2Sn-3Zr(TLM) alloy for biomedical applications via one-step anodization process in ethylene glycolbased electrolyte containing 0.5wt% NH4F.The nanostructured TiO2 films exhibited three distinct types depending on the anodization time:top irregular nanopores(INP)/beneath regular nanopores(RNP),top INP/middle regular nanotubes(RNT)/bottom RNP and top RNT with underlying RNP.The evolution of the nanostructured TiO2 films with anodization time demonstrated that self-organizing nanopores formed at the very beginning and individual nanotubes originated from underlying nanopore dissolution.Furthermore,a modified two-stage self-organizing mechanism was introduced to illustrate the growth of the nanostructured TiO2 films.Compared with TLM titanium alloy matrix,the TiO2 films with special nano-structure hold better hydrophilicity and higher specific surface area,which lays the foundation for their biomedical applications.

Preparation of Nano-Particles (Pb,La)TiO_3 Thin Films by Liquid Source Misted Chemical Deposition

Nano particles lanthanum modified lead titanate (PLT) thin films are grown on Pt/Ti/SiO 2/Si substrate by liquid source misted chemical deposition (LSMCD). PLT films are deposited for 4-8 times, and then annealed at various temperature. XRD and SEM show that the prepared films have good crystallization behavior and perovskite structure. The crystallite is about 60 nm. The deposition speed is 3 nm/min. This deposition method can exactly control stoichiometry ratios, doping concentration ratio and thickness of PLT thin films. The best annealing process is to bake at 300 ℃ for 10 min and anneal at 600 ℃ for 1 h.

Fabrication of nanoporous TiO_2 films with novel surface morphology on conducting glass(FTO) substrate

The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morphology and high porosity, nanoporous TiO2 films were fabricated on conducting glass （FTO） substrates, Ti thin films （1.5-2 gin） were deposited on conducting glass （FTO） substrates via the DC sputtering method, and then electrochemically anodized in NH4F/ethylene glycol solution. The crystalline structure and surface morphology of the samples were characterized by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）, respectively. The influences of anodizing potential, electrolyte composition, and pH value on the surface morphology of nanoporous TiO2 films were extensively studied. The growth mechanism of nanoporous TiO2 films was discussed by current density variations with anodizing time. The results demonstrate that nanoporous TiO2 films with high porosity and three-dimensional （3D） networks are observed at 30 V, when the NH4F concentration in ethylene glycol solution is 0.3% （mass fraction） and the electrolyte pH value is 5.0.

Tradeoffbetween Narrowing Optical Band Gap and Enhancing Electrical Conductivity of the Metal Nanoparticles-Modified Titanium Oxide Films

The n-type semiconducting titanium oxide thin films are well-known as electron transporting interlayer in photovoltaic cells. The favorable characteristics of interlayers in photovoltaics are high optical transmittance （T%）, wide band gap energy （Eg） and high electrical conductivity （σ）. Modifying titanium oxide films with metal nanoparticles would increase electrical conductivity but reduce optical band gap energy. We developed the sol-gel derived titanium suboxide （TiOx） films modified with silver （Ag） or gold （Au） or copper （Cu） nanoparticles （NPs）. This study explores a tradeoff between narrowing optical band gap and enhancing electrical conductivity of nanostructured TiOx films by controlling the Au- or Ag- or Cu-NPs loading concentrations （mol%） in titania. The Au- and Cu-NPs loading concentration of 4 mol% should meet a tradeoff which yields the higher T%, wider Eg and higher compared to those of pure TiOx films. In addition, since the pure Cu is not thermodynamically stable in ambience as compared to Au and Ag, the stability of as-obtained colloidal CuNPs is also examined. A careful examination of the time evolution of surface plasmon resonance （SPR） bands of CuNPs indicates that their stability is only up to 4 h.

Efficient perovskite solar cells based on novel three-dimensional TiO2 network architectures

Mesoscopic lead halide perovskite solar cells typically use TiO2 nanoparticle films as the scaffolds for electron-transport pathway and perovskite deposition. Here, we demonstrate that swelling-induced mesoporous block copolymers can be templates for producing three- dimensional TiO2 networks by combining the atomic layer deposition technique. Thickness adjustable TiO2 network is an excellent alternative scaffold material for efficient per- ovskite solar cells. Our best performing cells using such a 270 nm thick template have achieved a high efficiency of 12.5 % with pristine poly-3-hexylthiophene as a hole transport material. The high performance is attributed to the direct transport pathway and high absorption of scaf- folds, small leakage current and largely reduced recombi- nation rate at interfaces. The results show that TiO2 network architecture is a promising scaffold for meso- scopic perovskite solar cells.

TiCl_4 assisted formation of nano-TiO_2 secondary structure in photoactive electrodes for high efficiency dye-sensitized solar cells

A new kind of photoactive electrodes with nanocrystalline TiO2(nano-TiO2)secondary structure is successfully prepared via a simple method of adding a small amount of TiCl4 2-propanol solution in conventional nano-TiO2 paste to form micro-sized nano-TiO2 aggregates.The benefits of this special structure include improved optical absorption,increased light scattering ability,and enhanced electron transport and collection efficiency.Dye-sensitized solar cells(DSCs)based on these photoactive electrodes show improved performance.The power conversion efficiency of the cells can be increased from 5.03%to 7.30%by substituting 6μm conventional nano-TiO2 thin film with the same thickness of as-prepared nano-TiO2 aggregates film in the photoactive electrodes.A higher power conversion efficiency of the cells can be obtained by further increasing the thickness of the nano-TiO2 aggregates film.

Effects of TiO_2 volume fraction on the microstructure and magnetic properties of CoPt-TiO_2 nanocomposite films

CoPt-TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers.The effects of TiO2 volume fraction on the microstructure and magnetic properties of the nanocomposite films were studied.Results showed that the ordering and texture of the L10-CoPt particles did not change with TiO2 content up to 76 vol.% of TiO2.However,the volume of the L10-CoPt particles in the film decreased with an increase in TiO2 content.Increasing TiO2 content effectively reduced the coalescence of magnetic grains when TiO2 content was larger than 56 vol.%.Both the out-of-plane coercivity and remanence ratio of the film decreased slightly with TiO2 content,but the in-plane coercivity and remanence ratio of the film decreased firstly and then increased after TiO2 content was larger than 56 vol.%.The reduction in the coercivity of the film should be due to the reduction in the size of the L10-CoPt particles.The reduction in remanence ratio might be due to the weakening of the exchange coupling strength between the magnetic grains when TiO2 content was increased,as indicated by the MFM images.

120 mm Single-crystalline perovskite and wafers： towards viable applications

As the large single-crystalline silicon wafers have revolutionized many industries including electronics and solar cells, it is envisioned that the availability of large single-crystalline perovskite crystals and wafers will revolutionize its broad applications in photovoltaics, optoelectronics, lasers, photodetectors, light emitting diodes(LEDs), etc. Here we report a method to grow large single-crystalline perovskites including single-halide crystals: CH3NH3PbX3(X=I, Br, Cl), and dual-halide ones:CH3NH3Pb(ClxBr1.x)3 and CH3NH3Pb(BrxI1.x)3, with the largest crystal being 120 mm in length. Meanwhile, we have advanced a process to slice the large perovskite crystals into thin wafers. It is found that the wafers exhibit remarkable features:(1)its trap-state density is a million times smaller than that in the microcrystalline perovskite thin films(MPTF);(2) its carrier mobility is 410 times higher than its most popular organic counterpart P3HT;(3) its optical absorption is expanded to as high as910 nm comparing to 797 nm for the MPTF;(4) while MPTF decomposes at 150 °C, the wafer is stable at high temperature up to270 °C;(5) when exposed to high humidity(75% RH), MPTF decomposes in 5 h while the wafer shows no change for overnight;(6) its photocurrent response is 250 times higher than its MPTF counterpart. A few electronic devices have been fabricated using the crystalline wafers. Among them, the Hall test gives low carrier concentration with high mobility. The trap-state density is measured much lower than common semiconductors. Moreover, the large SC-wafer is found particularly useful for mass production of integrated circuits. By adjusting the halide composition, both the optical absorption and the light emission can be fine-tuned across the entire visible spectrum from 400 nm to 800 nm. It is envisioned that a range of visible lasers and LEDs may be developed using the dual-halide perovskites. With fewer trap states, high mobility, broader absorption, and humidity resistance, it is expected that solar cells with high stable efficiency maybe attainable using the crystalline wafers.

Electron transport in dye-sensitized solar cells based on TiO_2 nanowires

Anatase titanium dioxide nanowire arrays were prepared by hydrothermally oxidizing titanium foils in aqueous alkali and transferred onto fluorinated tin oxide(FTO)glass for use as the photoanodes of front side illuminated dye-sensitized solar cells(DSCs).Electrochemical impedance spectroscopy(EIS)measurement was applied to compare the electron transport and recombination properties of DSCs using TiO2nanowire films and TiO2nanoparticle films as photoanodes.It was found that the nanowire array films possess smaller electron transport resistance(Rt)and larger electron diffusion length(Le)in the photoanodes,suggesting that the nanowire arrays can enhance the electron transport rate and have a potential to improve the charge collection efficiency of DSCs.

The effect of dispersion of TiO_2 nanoparticles on preparation of flexible dye-sensitized photoanodes

Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes was employed to improve the disper- sion of TiO2 nanoparticles, in order to prepare flexible photoanodes for dye-sensitized solar cells （DSCs） with novel photovol- talc properties at a low temperature. The effects of dispersion treatment on the dispersion of TiO2 nanoparticles, including the viscosities of the binder-free TiO2 paste, the morphologies and textural properties of nanoparticle-TiO2 films, and the photo- voltaic properties of the flexible DSCs, were investigated. Flexible indium-tin oxide （ITO）-coated polyethylene naphthalate （PEN） substrates with sputter deposited Pt were employed as the transparent flexible counter electrodes. A short-circuit photo- current density of 9.62 mA·cm^-2, an open-circuit voltage of 0.757 V, a fill factor of 0.589 and an overall light-to-energy con- version efficiency of 4.29% for the flexible DSCs under AM1.5 illumination of 100 mW·cm^-2 were obtained with dispersion treatment. A 30.8% increment of the energy conversion efficiency for DSCs made by dispersion treatment was obtained com- pared with that made without dispersion treatment.

Fabrication and characterization of transparent conducting titanium-zinc oxide nanostructured thin films

Nano transparent conducting titanium-zinc oxide(Ti-Zn O) thin films were prepared on glass substrates by radio frequency(RF) magnetron sputtering technique. The deposited films are characterized by X-ray diffraction(XRD), four-probe meter and UV-visible spectrophotometer. The effects of Ti-doping content on the structural, optical and electrical properties of the films are investigated. The XRD results show that the obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the(002) crystallographic direction. The structural and optoelectronic characteristics of the deposited films are subjected to the Ti-doping content. The Ti-Zn O sample fabricated with the Ti-doping content of 3%(weight percentage) possesses the best crystallinity and optoelectronic performance, with the highest degree of preferred(002) orientation of 99.87%, the largest crystallite size of 83.2 nm, the minimum lattice strain of 6.263×10^(-4), the highest average visible transmittance of 88.8%, the lowest resistivity of 1.18×10^(-3) Ω·cm and the maximum figure of merit(FOM) of 7.08×10~3 Ω^(-1)·cm^(-1). Furthermore, the optical bandgaps of the films are evaluated by extrapolation method and observed to be an increasing tendency with the increase of the Ti-doping content.

Formaldehyde gas sensor based on TiO_2 thin membrane integrated with nano silicon structure

An innovative formaldehyde gas sensor based on thin membrane type metal oxide of Ti O2 layer was designed and fabricated. This sensor under ultraviolet(UV) light emitting diode(LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the sensor under steady working condition were calculated for different gas concentrations. The sensitivity to formaldehyde of 7.14 mg/m^3 is about 15.91 under UV illumination with response time of 580 s and recovery time of 500 s. The device was fabricated through micro-electro-mechanical system(MEMS) processing technology. First, plasma immersion ion implantation(PIII) was adopted to form black polysilicon, then a nanoscale TiO_2 membrane with thickness of 53 nm was deposited by DC reactive magnetron sputtering to obtain the sensing layer. By such fabrication approaches, the nanoscale polysilicon presents continuous rough surface with thickness of 50 nm, which could improve the porosity of the sensing membrane. The fabrication process can be mass-produced for the MEMS process compatibility.