掺杂VO2相变薄膜的电阻突变特性研究

以V2O5和MoO3粉为原料，采用无机溶胶－凝胶法制备了掺Mo^6 的VO2相变薄膜。对掺杂薄膜的物相组成、价态、相结构的XPS和XRD分析及电阻突变量级和电阻突变温度的测试，结果发现：所制备的掺杂薄膜其主要成分是VO2，所掺入的MoO3与VO2完全互溶，但其中MoO3的价态未发生改变。掺杂薄膜随MoO3含量的增加其电阻突变温度明显下降，然而电阻突变量级也随之降低，当MoO3的质量分数为5％时，薄膜电阻突变温度降至30℃左右，电阻突变量级仍可保持2个数量级左右，尚能满足应用的要求。     

热处理V膜制备VO_2薄膜的结构和光电性能

先用磁控溅射法在石英玻璃基片上制备了金属V膜,然后经过真空退火处理被转变为VO_2薄膜。研究了退火温度对VO_2薄膜表面形貌、晶体结构、光学性能和电学性能的影响。结果表明:随着退火温度由300℃增加到450℃,VO_2薄膜的结晶度明显增加。退火温度在400℃和450℃制备的样品是高纯M相单斜结构,晶粒发育较好,晶界清晰。不同温度退火的样品的表面V元素包含由4+和5+态,5+态的出现是由于表面V元素受环境中氧化导致。虽然退火温度的改变对VO_2薄膜的可见光透过率无明显影响,但是可以改善对太阳光的调节效率。VO_2薄膜半导体-金属相变温度和半导体相的电阻随热处理温度增加而增加,在400℃和450℃退火样品电阻相变前后的变化幅度可达2个数量级,450℃退火制备样品的滞后宽度和半导体金属相变临界温度分别为14.6℃和61.0℃。     

衬底温度对MgxZn1-xO薄膜结构和光学性质的影响

以Mg0.4Zn0.6O为靶材,采用射频磁控溅射方法在石英玻璃衬底上沉积MgxZn1-xO薄膜.利用能量色散X射线谱分析了不同衬底温度下制备的薄膜中Mg含量;用X射线衍射和吸收光谱研究了物相结构及其光学性质.结果表明:不同衬底温度下制备的MgxZn1-xO薄膜均为六方纤锌矿结构,且具有良好的c轴取向.衬底温度为200℃...     

热处理V膜制备VO_(2)薄膜的结构和光电性能EI北大核心CSCD

先用磁控溅射法在石英玻璃基片上制备了金属V膜,然后经过真空退火处理被转变为VO_(2)薄膜。研究了退火温度对VO_(2)薄膜表面形貌、晶体结构、光学性能和电学性能的影响。结果表明:随着退火温度由300℃增加到450℃,VO_(2)薄膜的结晶度明显增加。退火温度在400℃和450℃制备的样品是高纯M相单斜结构,晶粒发育较好,晶界清晰。不同温度退火的样品的表面V元素包含由4+和5+态,5+态的出现是由于表面V元素受环境中氧化导致。虽然退火温度的改变对VO_(2)薄膜的可见光透过率无明显影响,但是可以改善对太阳光的调节效率。VO_(2)薄膜半导体-金属相变温度和半导体相的电阻随热处理温度增加而增加,在400℃和450℃退火样品电阻相变前后的变化幅度可达2个数量级,450℃退火制备样品的滞后宽度和半导体金属相变临界温度分别为14.6℃和61.0℃。     

热处理对电沉积制备CuInGaSe2薄膜的影响

CuInGaSe2薄膜太阳能电池因具有稳定、高效、低成本和环保等特点而受到国内外科学家的重视．采用Mo／钠钙玻璃衬底为研究电极，饱和甘汞电极(SCE)为参比电极，大面积的铂网电极为辅助电极的三电极体系，在钼／钠钙玻璃衬底上利用电沉积技术制备出太阳能电池用的CuInGaSe2薄膜．分析了不同热处理温度对电沉积制备的CuInGaSe2薄膜的影响，结果表明：当热处理温度为450℃时，所制备的CuInGaSe2薄膜的化学组成接近理想的化学计量比，薄膜具有黄铜矿结构，颗粒均匀和致密性较好．     

二氧化钒薄膜制备研究的最新进展

VO2在68℃附近发生从高温金属相到低温半导体相的突变,且相变可逆。由于相变前后其电、磁、光性能有较大的变化,使得它在光电开关材料、存储介质、气敏传感器和智能玻璃等方面有着广泛的应用。然而由于VO2稳定存在的组分范围狭窄,使得制备高纯度VO2薄膜较为困难。为此人们做了很多工作来研究VO2薄膜的制备。本文综述了2000年以来VO2薄膜制备方法的研究情况,比较了各种制备方法对薄膜性能的影响,介绍了VO2薄膜研究的最新研究进展,并为扩大其应用领域而探讨了今后的研究方向。     

衬底温度对MgxZn1-xO薄膜结构和光学性质的影响

以Mg0.4Zn0.6O为靶材,采用射频磁控溅射方法在石英玻璃衬底上沉积MgxZn1–xO薄膜。利用能量色散X射线谱分析了不同衬底温度下制备的薄膜中Mg含量;用X射线衍射和吸收光谱研究了物相结构及其光学性质。结果表明:不同衬底温度下制备的MgxZn1–xO薄膜均为六方纤锌矿结构,且具有良好的c轴取向。衬底温度为200℃时,制备的薄膜样品的(002)方向衍射峰强度最大,表明此温度下薄膜的结晶程度最高。衬底温度为300℃时,制备的薄膜样品中Mg的含量最高为0.438 mol,其室温下吸收光谱的吸收边位于281 nm。     

直流磁控溅射工艺对ITO薄膜光电性能的影响

采用直流磁控溅射系统在玻璃衬底上制备了氧化铟锡(ITO)薄膜。通过X射线衍射仪、扫描电子显微镜、分光光度计、Hall效应测试系统研究了热退火与原位生长、衬底温度、直流溅射功率对薄膜结构、表面形貌以及光电性能的影响。结果表明:与室温生长并经410℃热退火后的薄膜相比,410℃原位生长可获得光电性能更好的薄膜;随着衬底温度的增加,电阻率单调减小,光学吸收边出现蓝移;在溅射功率为85 W时薄膜的光电性能达到最佳。在衬底温度为580℃、溅射功率为85 W的工艺条件下,可制备出电阻率为1.4×10~(–4)?·cm、可见光范围内平均透过率为93%的光电性能优异的ITO薄膜。     

衬底温度调制生长GZO薄膜的性能研究

利用射频磁控溅射法在石英玻璃衬底上制备ZnO∶Ga透明导电氧化物薄膜,主要研究了一种类调制掺杂工艺对GZO薄膜的薄膜形貌结构和光电性能的影响。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见-近红外分光光度计(UV-VIS-NIR)和四探针测试仪对GZO薄膜进行表征。结果表明:不同的衬底温度调制下生长的GZO薄膜都具有明显的c轴择优取向,对于衬底温度调制条件下,在150℃/RT条件下的薄膜结晶最好,且在可见近红外波段(480~1600 nm)平均透过率达到85.4%左右,薄膜最低方阻达到60Ω/□。     

热处理对Sb∶SnO_2透明导电薄膜光电性能的影响

由烧结法制备了5Sb_2O_5·95SnO_2(mol%)陶瓷靶材,以所制靶材利用射频磁控溅射法在石英玻璃基片上制备得到高质量的Sb∶Sn O2(ATO)透明导电薄膜,研究了热处理温度对ATO薄膜的结构和光学与电学性能的影响。结果表明:热处理对ATO薄膜的相结构,结晶质量及性能均有一定的影响。随着温度升高,所制薄膜的晶粒尺寸逐渐长大,方块电阻逐步减小,最小值为9.3Ω/;红外反射率先增大后减小,并在热处理温度为600℃时达到极大值,为89%。薄膜可见光透过率均在80%以上,温度为600℃时最高达到91.3%。     

QUALITATIVE OBSERVATIONS OF HEAT AND MASS TRANSFER EFFECTS ON THE BEHAVIOUR OF A TRICKLE BED REACTOR

This paper examines the effect of simultaneous heat and mass transfer on the hydrogenation of cyclohexene in a trickle bed reactor with particular attention given to the problem of liquid phase evaporation and transition to the gas-phase regime of operation. The reaction rates are obtained as a function of temperature and hydrogen flow rate; the concentration of the substrate in the feed displays considerable hysteresis due to an abrupt increase of the reaction rate arising from temperature gradients within the bed and in the gas film surrounding the catalyst pellet, during the transition from the liquid to the gas-phase regime. The transition is accompanied by the change of apparent kinetics of the model reaction as well as by a change of regime and operation of the pellet. In the liquid phase a pellet originally showing inter-phase and intra-particle diffusion resistances changes into the gas-phase regime with a large resistance due to inter-phase diffusion.     

Preparation and properties of pure crystalline perovskite CeFeO3 thin films with vanadium doping

Cerium ferrite (CeFeO₃) thin films doped with vanadium (V:CeFeO₃) were grown on SiO₂ quartz glass and <100>‐oriented SrTiO₃ (STO) crystal substrates by the radio‐frequency magnetron sputtering method in this study. The effects of crystallization, substrate, and V‐doping on the quality, the magnetic property and the magneto‐optical property of as‐prepared films are investigated. V:CeFeO₃ film grown on STO substrate has better crystallinity and has better lattice integrity due to the higher lattice matching between substrate and film. The magnetic hysteresis loop and the magnetic circular dichroism spectra show that the magnetization strength and the magneto‐optical properties of V:CeFeO₃ films have the significant anisotropy. Moreover, V‐doping and the stress lead to the change in easy magnetization direction of film. It shows that the perovskite B‐site doping with transition‐metal ion has significant influence on the magnetic and the magneto‐optical properties of CeFeO₃ thin films.     

聚乙烯醇纳米薄膜结晶的初步研究

通过加热70 nm的聚乙烯醇(PVA)纳米薄膜至玻璃化转变温度之上,初步研究了纳米薄膜的结晶现象。研究表明,PVA纳米薄膜具有很好的结晶性,可以得到较高的结晶度,且结晶度显著依赖于退火温度。在160 oC以上结晶时,表面会形成棒状晶体。     

Aging-Induced Double Ferroelectric Hysteresis Loops and Asymmetric Coercivity in As-Deposited BiFe0.95Zn0.05O3 Thin Film

The BiFe_0.95Zn_0.05O₃ (BFZO) thin film was fabricated on indium tin oxide/glass substrate using a metal organic decomposition method combined with sequential layer annealing. Double ferroelectric hysteresis loops were observed in the as-deposited film, indicating that the film is partially aged. This aging phenomenon can be attributed to the formation of defect complexes between oxygen vacancies and acceptors of     in the film. The nonreversible transition from double ferroelectric hysteresis loop to the single one can occur during the course of increasing the applied electric field. More importantly, an asymmetry of the coercive field can be found to be strongly dependent on the magnitude and frequency of the electric field. This phenomenon was discussed based on the asymmetric driving force for domain backswitching in BFZO film with a preferential polarization.     

Temperature-induced strain mediated magnetization changes in NiFe2O4/BaTiO3 heterostructure

Herein, we report the temperature-induced magnetization changes of NiFe₂O₄ thin film, which is coated over a ferroelectric BaTiO₃ ceramic substrate. The solid-state reaction method was adopted for the preparation of ferroelectric BaTiO₃ (BT) substrate, whereas NiFe₂O₄ (NFO) film was deposited by spin-coating method. Rietveld refinement revealed that BT substrate has a tetragonal (P4mm) crystal system along with a minor orthorhombic phase (Amm2) at room temperature. The GIXRD analysis confirms the phase purity of NFO/BT heterostructure. Polarization hysteresis with respect to electric field (P-E loop) and the temperature-dependent dielectric measurement of BT substrate demonstrate its typical ferroelectric and phase transition behavior, respectively. Magnetization hysteresis loops were recorded for the NFO/BT heterostructure at 150, 240 and 300?K. A significant increase in the remnant magnetization (M_R) and coercive field (H_C) of NFO film are noticed while cooling the heterostructure below 300?K. Variation in the magnetization of NFO film corresponds to the change in the structural phase transition (Amm2 at 240?K and R3c at 150?K) of BT while cooling below RT. The interfacial strain mediated coupling is the primary mechanism attributed to the temperature-induced changes in the magnetization of NFO/BT heterostructure.     

Quartz crystal resonator study of glass transitions in polyvinylbutyral (PVB) films

Glass transitions in polyvinylbutyral (PVB) films deposited on a gold substrate have been studied using a quartz crystal resonator technique by measuring the resonant frequency shift and resonant peak broadening of the quartz crystal coated with a PVB film. Using the measured frequency shift and peak broadening of the resonance of the quartz crystal due to changes in the coated PVB film, the storage moduli of the film were derived. The results show rapid drops in the storage moduli of the PVB films at temperature closer to that of glass transition of bulk PVB. The transitions at different frequencies were assessed by simultaneously measuring the resonance of the quartz crystal at multiple harmonics. No significant change in the glass transition temperature at multiple harmonics was observed. The results of the storage moduli for PVB films of different thickness show that glass transition temperatures in the films decrease with the film thickness; the decrease become more noticeable as the film thickness is less than 500 nm where the characteristic of changing of storage moduli become distinctly different from that in thicker film and in bulk materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45433.     

The FRL-FRH phase transition in PZT 95/5 thin film

The PZT 95/5 thin film was prepared on Pt/Ti/ SiO₂Si substrate by sol-gel method. The behavior of F_RL-F_RH phase transition was investigated in the thin film. The change of the remanent spontaneous polarization during the F_RL-F_RH phase transition is 0.6 μc/cm².     

Probing the viscoelastic moduli of thin,soft films with a quartz crystal resonator

Coating biomaterials with thin, soft films can alter properties, such as the biocompatibility of the materials, whereas it remains a great challenge to probe the properties of such films. In this article, we show a method that allows for the determination of the viscoelastic moduli of thin, soft films deposited on the surface of a quartz crystal through the measurement of resonance frequency shifts and the broadening of the acoustic resonance of the crystal as a resonator. The method is based on transcendental equations, which describe the mechanical response of the quartz resonator with the deposited films. It differs from the currently widely used ones, which use a thin film approximation numerically through the solution of transcendental equations to determine the viscoelasticity of the films. We estimated the glass‐transition temperature of a thin poly(vinyl butyral) film by measuring the change in the viscoelastic moduli of the film with increasing temperature, and the results agree well with the temperature obtained from other techniques. The method was not constrained to the range of the elastic moduli of the film, except where the acoustic film resonance occurred, and thus, could be applied to the study of a wide variety of thin, soft layers under different conditions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44532.     

在线APCVD镀膜玻璃渐变过渡层性能研究

通过在线常压化学相沉积镀膜手段制备了FTO玻璃的单层硅/锡混合过渡膜层,并通过各种分析手段测试了可见光透过率、方块电阻、膜层表面结构及纵向元素分布等性能,研究了其结构组成对各项性能的影响.结果表明:膜层中Sn含量由表面至基底玻璃逐渐减小同时Si含量逐渐增加,为良好的SiO2/SnO2渐变结构膜层;膜层可见光透过率主要由其膜层结构决定,在一定的范围内,可以通过调整膜层的渐变结构来改变其可见光透过率;表层致密程度及膜层结构渐变可以改善膜层的导电性;可作为FTO镀膜玻璃的过渡层使用.     

Sealing Glass‐Ceramics with Near‐Linear Thermal Strain,Part II: Sequence of Crystallization and Phase Stability

The sequence of crystallization in a recrystallizable lithium silicate sealing glass‐ceramic Li₂O–SiO₂–Al₂O₃–K₂O–B₂O₃–P₂O₅–ZnO was analyzed by in situ high‐temperature X‐ray diffraction (HTXRD). Glass‐ceramic specimens have been subjected to a two‐stage heat‐treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass‐ceramic having a near‐linear thermal strain, as opposed to the highly nonlinear glass‐ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass‐ceramics. While the inversion in cristobalite resembles the character of a first‐order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Localized tensile stresses on quartz and possible solid‐solution effects have been attributed to the transition behavior of quartz crystals embedded in the glass‐ceramics.