Pr和V掺杂的Bi4Ti3O12铁电陶瓷的微结构及电性能

采用传统固相烧结法制备了Pr6O11和V2O5共同掺杂的Bi4Ti3O12铁电陶瓷。XRD分析表明,Pr6O11和少量V2O5的掺杂没有引起材料结构的改变。适当比例Pr6O11的掺杂会使材料的铁电性能有明显的改善,但其电输运特性明显不同于3价稀土离子的掺杂。实验表明,钒掺杂对材料铁电性能的影响主要体现在低电场下,不能简单地以氧空位的变化来解释。配比为Bi3.08Pr0.75Ti2.98V0.02O12的样品的电学性能稳定并且具有较大的剩余极化。     

声电输运器件的沟道特性研究

为实现砷化镓声电输运,必须在外延层中建立电子输运沟道.本文对金属-n型外延层-半绝缘衬底结构的输运沟道给出耗尽分析的解析表达式,分析了外延层厚度、掺杂浓度、偏置电压等参数对输运沟道耗尽特性的影响,以及器件表面存在氧化层时对器件工作特性的影响.     

非掺杂InP中深陷阱与载流子的产生和输运的影响

利用四波混频(FWM)技术对未掺杂双面抛光的InP晶片进行了测试分析.室温下在1064nm用时间分辨皮秒四波混频技术测试了材料的载流子的产生、复合、衰减动力学以及曝光特性等过程.阐明了InP中深陷阱在载流子的产生与输运中的作用,并给予了解释.未掺杂InP样品的衍射效率作为能量函数可用两个光栅周期来表达.未掺杂InP样品中的深施主缺陷也由空间电荷载流子的输运过程来证实.     

非掺杂InP中深陷阱与载流子的产生和输运的影响

利用四波混频(FWM)技术对未掺杂双面抛光的InP晶片进行了测试分析.室温下在1064nm用时间分辨皮秒四波混频技术测试了材料的载流子的产生、复合、衰减动力学以及曝光特性等过程.阐明了InP中深陷阱在载流子的产生与输运中的作用,并给予了解释.未掺杂InP样品的衍射效率作为能量函数可用两个光栅周期来表达.未掺杂InP样品中的深施主缺陷也由空间电荷载流子的输运过程来证实.     

InPδ掺杂的输运特性

测量了用MOCVD技术制造的InP δ掺杂样品的磁输运特性,量子化Hall效应和高电场下的热电子效应.得到了该样品的载流子分布,子能带结构,杂质传播宽度和电子迁移率等基本物理参数,观察到填充因子v=2的量子Hall平台和负微分电阻现象,建立和证实了δ掺杂样品的热电子传输模型.     

La和Sr的掺杂对PZT薄膜电学性质的影响

该文采用溶胶-凝胶法在LaNiO_3/Pt/Ti/SiO_2/Si基片上制备了掺杂La元素的Pb_(1-0.05)La_(0.05)ZrTiO_3(PLZT)、掺杂Sr元素的Pb_(1-0.05)Sr_(0.05)ZrTiO_3(PSZT)、掺杂La和Sr元素的Pb_(1-0.1)La_(0.05)Sr_(0.05)ZrTiO_3(PLSZT)及未掺杂的锆钛酸铅(PZT)薄膜样品。对不同掺杂情况的样品分别进行了压电系数、电滞回线、介电特性的测试。结果表明,双掺杂样品PLSZT薄膜具有比其他样品更好的铁电性能,其剩余极化强度(P_r)为13.2μC/cm~2,饱和极化强度(P_s)为28.4μC/cm~2,矫顽场(E_c)为54.8 kV/cm;双掺杂样品PLSZT薄膜的压电系数(d_(33))比其他3种样品高,达到153 pC/N。掺杂后的样品与未掺杂的样品相比,其介电常数有略微提高;单掺杂La的样品的介电特性在高频环境下更稳定。     

Nd掺杂对BiFeO3薄膜微结构和电学性能的影响

采用化学溶液方法,在LaNiO3/Si(100)衬底上生长了Nd掺杂的BiFeO3薄膜.XRD分析结果表明,随着Nd掺杂量的增加,薄膜晶格变小,Nd掺杂量为20%时,薄膜出现杂相.介电测试表明,随着Nd掺杂量的增加,介电常数和损耗减小,Nd掺杂量为2%的薄膜表现出很强的介电色散现象并出现介电损耗弛豫峰,其符合类德拜模型特征.随着Nd掺杂量增加,薄膜的漏电流减小,在低电场下,电流输运遵从SCLC模型,在高场下,电流输运遵循Poole-Frenkel模型.分析结果表明Nd掺杂对薄膜微结构和电学性能有显著影响.     

氮掺杂对单壁碳纳米管的非平衡电子输运特性的影响

利用结合了非平衡格林函数的第一性原理的局域密度泛函理论,研究了氮原子取代掺杂单壁碳纳米管的输运特性.计算结果表明,不同构形和不同数目的氮原子掺杂对(8,0)单壁碳管的输运性能有复杂的影响.研究发现,氮原子的掺杂提高了半导体型碳管的输运性能,电流-电压曲线呈非线性变化.对于浓度相同的氮掺杂,原胞内最近邻氮原子间距极大地影响了碳管的输运性能.因此,基于掺杂管的分子器件的设计中很有必要考虑这些因素.     

氮掺杂对单壁碳纳米管的非平衡电子输运特性的影响

利用结合了非平衡格林函数的第一性原理的局域密度泛函理论,研究了氮原子取代掺杂单壁碳纳米管的输运特性.计算结果表明,不同构形和不同数目的氮原子掺杂对(8,0)单壁碳管的输运性能有复杂的影响.研究发现,氮原子的掺杂提高了半导体型碳管的输运性能,电流-电压曲线呈非线性变化.对于浓度相同的氮掺杂,原胞内最近邻氮原子间距极大地影响了碳管的输运性能.因此,基于掺杂管的分子器件的设计中很有必要考虑这些因素.     

掺杂单壁碳纳米管的电流特性

依据Boltzmann方程及单壁碳纳米管(SWNTs)能量色散关系,对单个掺杂SWNTs(金属型和半导体型)所加偏压、掺杂浓度及管口直径影响输运电流的性质进行数值计算.分析表明,掺杂SWNs中的电流随偏压变化呈现跃变结构;管口直径、掺杂后Fermi能级附近的态密度以及各通道输运电子的能力直接决定电流的特性,如电流强度、跃变间隔及跃变幅度;同时电流的特性也与温度有关.     

Facile synthesis and enhanced trimethylamine sensing performances of W-doped MoO3 nanobelts

The pure and W-doped MoO₃ nanobelts were prepared via a facile one-step hydrothermal method. The morphology and microstructure of the developed nanobelts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The characterization results showed that as-prepared samples are uniform nanobelts with a mean length of 20 µm and width range of 100–200 nm, and W element was distributed uniformly in MoO₃ nanobelts. The comparison between pure and doped samples was carried out to reveal the superior gas sensing performance of W-doped MoO₃ nanobelts. The results of sensing properties indicate that the sensors based on W-doped MoO₃ nanobelts exhibit high response, good selectivity, and long term stability characteristics towards trimethylamine (TMA) gas, which are promising for trimethylamine sensors used to monitor air-quality and environmental.     

Photoelectrochemical Activities of W-Doped Titania Nanotube Arrays Fabricated by Anodization

Titania nanotube arrays and W-doped (containing 3-wt% W) titania nanotube arrays were obtained using a direct anodization method in ethylene glycol electrolyte containing 0.5-wt% HF at 60 V. Anneal was conducted to get anatase crystals. The microstructure and crystal structure of the nanotubes were characterized by scanning electron microscopy and X-ray diffraction. The ultraviolet-visible diffuse reflectance spectra of the annealed samples show that the addition of W led to the red shift of absorbance edge and a decrease of bandgap energy for about 0.14 ev. The photoelectrochemical behavior of these samples has been also studied. Results show that photocurrent densities of W-doped titania nanotube arrays were much larger than that of the undoped sample.     

Combinatorial Development of Blue OLEDs Based on Star Shaped Molecules

In this paper we describe the use of combinatorial vapor deposition techniques for the optimization of blue organic light emitting diodes (OLEDs). In these devices the star shaped molecule 1 with a triphenylamine core and three fluorene side groups serves as hole transport and emitting layer. Compound 2 with a much lower lying HOMO and a larger bandgap is used as hole blocking layer. Using combinatorial vapor deposition 42 OLEDs with thickness gradients of both the hole transport and the hole blocking layer have been simultaneously prepared on one substrate. The physical characterization of the devices clearly shows that a hole blocking layer of the star shaped molecule 2 is necessary in order to obtain pure blue emission with CIE coordinates of x = 0.15 and y = 0.15. A thickness of only 5 nm of the blocking layer is sufficient, and with increasing layer thickness the brightness of the blue devices drops. The blue devices exhibit a brightness of 400 cd m^–2 and a luminous efficiency of 2 cd A^–1. The thickness variations of both the hole transport and the hole blocking layer have been made in one combinatorial evaporation experiment on a single substrate using a set of movable masks. This demonstrates how efficient combinatorial methods can be used for the development of OLEDs.     

MmNi5-基储氢合金扫描电镜能谱仪定量分析

使用配备ＥＤＳ的ＳＥＭ,研究了ＭｍＮｉ５－基储氢合金的微观组织和微区成分。研究的合金中稀土元素含量低于化学比,晶界有Ｃｏ,Ｍｎ和Ａｌ富集相析出。分别使用ＲｅＢ６、ＲｅＰ５Ｏ和纯稀土金属作为分析稀土元素的标样进行定量分析。结果表明,全部采用纯金属标样（包括纯稀土金属标样）分析结果最好;采用ＲｅＢ６和ＲｅＰ５Ｏ１４作为分析稀土的标样时,分析误差较大。文章对误差较大的产生原因进行了讨论。     

Evaluation of the Thermoelectric Module Consisting of W-Doped Heusler Fe2VAl Alloy

Power generation performance of a thermoelectric module consisting of the Heusler Fe₂VAl alloy was evaluated. For construction of the module, W-doped Fe₂VAl alloys were prepared using powder metallurgy process. Power generation tests of the module consisting of 18 pairs of p–n junctions were conducted on a heat source of 373–673 K in vacuum. The reduction of thermal conductivity and improvement of thermoelectric figure of merit by W-doping enhanced the conversion efficiency and the output power. High output power density of 0.7 W/cm² was obtained by virtue of the high thermoelectric power factor of the Heusler alloy. The module exhibited good durability, and the relatively high output power was maintained after temperature cycling test in air.     

A Color Stable Blue Light-Emitting Device Using a Pyrazolo[3,4-b]Quinoline Derivative as an Emitter

A color stable and pure blue multilayered light-emitting device is obtained via suppressing voltage-dependent color change. Photophysical properties of a blue fluorescent organic compound 1-phenyl-3,4-dimethyl-1H-pyrazolo[3,4-b]-quinoline (PAQ5) are investigated; its highest occupied and lowest unoccupied molecular orbital levels are also measured. A multilayer electroluminescent device is fabricated using PAQ5 as an emitter dopant in a polymer matrix. The dopant has several functions in balancing injection and transport as well as bright blue light emission. The multilayered device using PAQ5 dopant substantially reduces voltage-dependent color changes, enhances the brightness of the device, and stabilizes general performance of the device. A color stable and pure blue electroluminescence with Commission Internationale de L'Eclairage (CIE) color coordinates of $({x},{y})=(0.168,0.100)$ is achieved.      

Pure Blue Electroluminescence by Differentiated Ion Motion in a Single Layer Perovskite Device

Blue electroluminescence is highly desired for emerging light-emitting devices for display applications and optoelectronics in general. However, saturated, efficient, and stable blue emission has been challenging to achieve, particularly in mixed-halide perovskites, where intrinsic ion motion and halide segregation compromises spectral purity. Here, CsPbBr_3−xCl_x perovskites, polyelectrolytes, and a salt additive are leveraged to demonstrate pure blue emission from single-layer light-emitting electrochemical cells (LECs). The electrolytes transport the ions from salt additives, enhancing charge injection and stabilizing the inherent perovskite emissive lattice for highly pure and sustained blue emission. Substituting Cl into CsPbBr₃ tunes the perovskite luminescence from green through blue. Sky blue and saturated blue devices produce International Commission on Illumination coordinates of (0.105, 0.129) and (0.136, 0.068), respectively, with the latter meeting the US National Television Committee standard for the blue primary. Likewise, maximum luminances of 2900 and 1000 cd m⁻², external quantum efficiencies (EQEs) of 4.3% and 3.9%, and luminance half-lives of 5.7 and 4.9 h are obtained for sky blue and saturated blue devices, respectively. Polymer and LiPF₆ inclusion increases photoluminescence efficiency, suppresses halide segregation, induces thin-film smoothness and uniformity, and reduces crystallite size. Overall, these devices show superior performance among blue perovskite light-emitting diodes (PeLEDs) and general LECs.     

雷达刷丝导电环钯镍合金镀膜技术研究

描述了针对雷达刷丝-导电环采用钯镍合金镀膜的技术,对铝青铜材质的导电环刷丝面进行电镀,达到耐磨性钯镍合金膜层结构,以满足产品所需要的耐磨和导电要求。研究了钯镍合金溶液的钯离子浓度参数变化,以及参数变化对刷丝面镀层钯镍百分比含量的影响。结合镀金层对实验结果进行分析,讨论了各种现象出现的原因。     

Hot electron conduction of PbTe and Pb1−xSnxTe

Experimental and theoretical studies have been made of electron transport and hot electron effects in PbTe and Pb_1?xSn_xTe as a function of alloy composition. Pulsed measurements of the current-voltage characteristics, Hall effect, and the potential distribution were made on epitaxial samples. Current instabilities and high field domain formation were observed. Monte-Carlo calculations of the velocity-field characteristic including the scattering into conduction band W valleys were performed. Reasonable agreement was obtained for the threshold field dependence on alloy composition.     

Facile synthesis of Er:CuS flowers and their application in the photo-catalytic activity

An easy one–pot synthesis rout has been employed to prepare 3D dimensional Er doped CuS hierarchical flower–like structures (HNs), is composed or assembled of nanoplates. Introduction of trivalent Er³⁺ into CuS crystals and consequence replacement with monovalent Cu¹⁺ generates free holes in valence band which caused an increase intensity plasmonic resonance in the infrared region, which has been studied by Uv–vis–NIR spectroscopy. In addition, Er³⁺ doped CuS can remarkably changes the defect of CuS HNs which has been studied by photoluminescence. The Er doped CuS nanocrystals exhibited enhanced photocatalytic activity compared with pure CuS for the degradation of methylene blue due to higher electron transport and production of HO• that is due to the effect of doping.