玻璃微球表面辉光等离子体聚合物涂层的热稳定性研究

采用辉光放电聚合技术,在不同工作压强条件下在直径为350—400 μm,厚度为2.5—3 μm的玻璃微球上制备了辉光放电聚合物 (GDP)涂层,并对玻璃/GDP微球模拟充气过程进行了热稳定性实验.利用傅里叶变换红外光谱仪、元素分析仪、热重法、体视显微镜和X射线照相技术对GDP涂层的内部结构及其化学键、热稳定性、微球形貌和厚度进行了表征.结果表明:GDP涂层中的碳氢比、不饱和键和C C含量随着制备压强的增大而减小,低压的热稳定性较好,GDP涂层与玻璃微球的结合力提高,流变、起泡和脱层现象也得到明显改善.微球 关键词： 玻璃微球 GDP涂层 热稳定性 结合力     

辉光放电聚合物结构及力学性质研究

采用低压等离子体聚合技术,通过调整工作气压和反式二丁烯(T₂B)与H₂流量比制备了辉光放电聚合物(GDP)涂层. 利用傅里叶变换红外吸收光谱和元素分析法讨论了工作气压和T₂B与H₂流量比对GDP涂层内部H原子含量及结构的影响,并且通过纳米压痕技术对GDP涂层的硬度及杨氏模量进行了表征.研究结果表明:降低工作气压和T₂B与H₂流量比,GDP涂层内sp³ C 关键词： 傅里叶变换红外光谱 纳米压痕 杨氏模量 硬度     

射频功率对辉光放电聚合物结构和性能的影响

采用辉光放电技术,利用三倍频射频电源制备了不同功率下的辉光放电聚合物(GDP)涂层.并对GDP涂层进行了傅里叶变换红外吸收光谱(FT-IR)和元素分析仪表征,讨论了功率变化对其内部结构的影响.利用热重法(TG)表征了GDP涂层在30—650 ℃范围内的热稳定性.结果表明:随着射频功率的提高,GDP涂层的沉积速率增大;SP³CH₃和联结甲基的乙烯基强度明显减小,SP³CH₂, SP²CH_{2 关键词： GDP涂层 红外吸收谱 热稳定性 射频功率}     

a-C:H膜化学结构对光学性能的影响

选用体积分数为99.999 9%的H2及反式-2-丁烯(T2B)为工作气体,利用低压等离子体增强化学气相沉积法制备了a-C;H薄膜.利用傅里叶变换红外光谱仪和X射线光电子能谱对薄膜化学键和电子结构进行分析,并结合高斯分峰拟合分析了薄膜中sp3/sp2杂化键比值和sp3C杂化键分数.结果表明:薄膜中氢含量较高,主要以sp3C-H形式存在;工作气压越高,制备的薄膜中C=C键含量越少,薄膜中sp3/sp2杂化键比值和sp3C杂化键分数增加,薄膜稳定性提高.应用UV-VIS光谱仪,获得了波长在400～1 000 nm范围内薄膜的光吸收特性,结果显示:a-C:H薄膜透过率可达98%.光学常数公式计算得到工作压强为4～14 Pa时光学带隙在2.66～2.76之间,并均随着工作气压的升高而增大.结果表明,随工作气压的升高,薄膜内sp3键减小,从而促使透过率、光学带隙增大.     

α-C:H膜表面形貌及光学性能的测试分析

 以H₂和反式-2-丁烯（T₂B）为工作气体,利用低压等离子体增强化学气相沉积法制备了α-C:H薄膜。采用原子力显微镜、扫描电镜测试了α-C:H薄膜的表面形貌,分析了实验参数对其形貌的影响。研究表明：固定压强(15 Pa),当T₂B/H₂流量比为4时,薄膜均方根粗糙度可达0.97 nm。保持T2B/H2流量比固定,增加工作气压,薄膜均方根粗糙度减小,表面更平整、致密。利用傅里叶变换红外光谱仪对薄膜价键结构进行分析,结果表明：α-C:H薄膜中主要存在sp3C—H键,氢含量较高;T₂B/H₂流量比越低,薄膜中含有更多的C=C键。应用UV-VIS光谱仪,获得了波长在200～1 100 nm范围内薄膜的光吸收特性,α-C:H薄膜透过率可达98%,计算得到的折射率在1.16～1.40。随工作气压的增加,α-C:H薄膜中sp³杂化键增多,透过率、折射率增大。     

FTIR分峰拟合法定量分析精制煤沥青热转化过程的结构变化

精制煤沥青(QI＜0.2%)是制备煤系针状焦的原料，其热转化性质决定着所生产的煤系针状焦的质量。利用FTIR光谱及分峰拟合的方法考察了精制煤沥青在不同热转化温度下的结构变化。主要研究了芳香性指数(Iar)、支链化指数(CH₃/CH₂)、各基础官能团(C==O， C-O，芳环C==C)含量、芳环取代种类的变化情况。结果表明：精制煤沥青的Iar指数随着热转化温度的提高，逐渐变大，并且CH₃/CH₂指数逐渐增大，说明精制煤沥青热转化过程中支链的断裂形成活性位点是诱导芳香环增大的原因之一；随着热转化温度的升高，C==O含量由最初的26.25%降低为15.62%，芳环C==C含量由43.39%增加为51.28%，而C-O含量变化很少，说明C==O是诱导大分子芳环缩合反应的重要因素；精制煤沥青中芳环1H和3H含量随着温度升高逐渐减小，而4H含量逐渐升高，说明芳环取代逐渐减小，芳香性逐渐增加，与Iar分析结果相吻合。     

GDP/D-GDP化学结构与力学性能的研究

利用低压等离子体增强化学气相沉积技术制备碳氢辉光放电聚合物(GDP)和全氘代辉光放电聚合物(D-GDP)薄膜。利用表面轮廓仪、傅里叶红外光谱仪和纳米压痕技术对制备的样品进行表征,讨论了GDP/D-GDP薄膜的沉积速率、化学结构和力学性能在ICF物理实验用靶应用中的优缺点。结果表明:GDP/D-GDP薄膜的沉积速率都随反应气体流量比例近线性增加,GDP的沉积速率达到2.6μm,D-GDP的沉积速率达到1μm,GDP的沉积速率远大于D-GDP的沉积速率;D-GDP薄膜内部的交联化程度较弱,D-GDP更有利于靶丸内燃料的红外均化;GDP的力学性能明显优于D-GDP,更有利于ICF物理实验用靶的燃料填充与装配操作。     

不同工作压强下辉光放电聚合物薄膜的表面形貌与光学性质

利用低压等离子体聚合技术在不同工作压强下制备了辉光放电聚合物(GDP)薄膜。利用原子力显微镜、傅里叶红外光谱仪、元素分析仪和紫外-可见光谱仪对GDP薄膜的表面形貌、化学结构、碳氢原子数比以及光学性质进行了表征。分析了工作压强对薄膜表面形貌、化学结构、碳氢原子比和光学性质的影响以及相互关系。结果表明:GDP薄膜的表面形貌随工作压强的增大而变得平整光滑,均方根粗糙度逐渐减小。随工作压强增大,GDP薄膜的化学结构的相互交联化程度减弱,C=C双键含量不断减小,碳氢原子数比不断减小,氢元素含量逐渐增大,薄膜的光学透过率截止波长发生"蓝移",光学间隙不断增加。     

椭偏法表征四面体非晶碳薄膜的化学键结构

采用自主研制的双弯曲磁过滤阴极真空电弧(FCVA)技术,在不同衬底负偏压下制备了四面体非晶碳(ta-C)薄膜。通过分光光度计和椭偏(SE)联用技术精确测量了薄膜厚度,重点采用椭偏法对不同偏压下制备的ta-C薄膜sp3 C键和sp2 C键结构进行了拟合表征,并与X射线光电子能谱(XPS)和拉曼光谱的实验结果相对比,分析了非晶碳结构的椭偏拟合新方法可靠性。结果表明,在-100V偏压时薄膜厚度最小,为33.9nm;随着偏压的增加,薄膜中的sp2 C含量增加,sp3 C含量减小,光学带隙下降。对比结果发现,椭偏法作为一种无损、简易、快速的表征方法,可用于ta-C薄膜中sp2 C键和sp3 C键含量的准确测定,且在采用玻璃碳代表纯sp2 C的光学常数及拟合波长选取250～1700nm时的椭偏拟合条件下,拟合数值最佳。     

硅掺杂辉光放电聚合物薄膜的热稳定性研究

采用等离子体辉光放电聚合技术,在不同四甲基硅烷(TMS)流量条件下制备了硅掺杂辉光放电聚合物(Si-GDP)薄膜,采用傅里叶变换红外光谱、X射线光电子能谱和热重(TG)分析技术分析了不同TMS流量对Si-GDP薄膜结构与热稳定性的影响.结果表明:随着TMS流量在0–0.06 cm³/min范围变化,Si-GDP薄膜中Si的原子含量C_Si为0–16.62%;含Si红外吸收峰的相对强度随TMS流量的增加而明显增大;Si-GDP薄膜的TG分析显示,温度在300 ℃时,随TMS流量的增加,Si-GDP薄膜的失重减少,热稳定性增强. 关键词： 硅掺杂辉光放电聚合物薄膜 X射线光电子能谱 热稳定性     

Er3+/Yb3+共掺碲硼硅酸盐玻璃的光谱性质和热稳定性研究

制备了系列Er³⁺/Yb³⁺共掺碲硼硅酸盐玻璃样品(85-x)TeO₂-15B₂O₃-xSiO₂ (TBS x=0,5,10,15,20 mol%).测试和分析了样品的吸收光谱、荧光光谱、能级寿命、红外透射光谱及差热特性.并通过对Er³⁺离子⁴I_13/2→⁴I_15/2跃迁发射谱线的高斯拟合，设计了一个简单的四能级结构估算了Er³⁺离子⁴I_13/2和⁴I_15/2能级在碲硼硅酸盐中的Stark分裂情况.研究表明SiO₂的引入能有效地改善玻璃的热稳定性和光谱性能，玻璃析晶温度T_x与玻璃转变温度T_g之差(ΔT=T_x-T_g)可达178℃，说明碲硼硅酸盐是一种适合于光纤拉制的玻璃基质材料.比较了不同基质玻璃中Er³⁺离子的荧光半高宽和受激发射截面，结果表明TBS玻璃系统具有较好的带宽性能，是一种优良的宽带光纤放大器候选基质材料. 关键词： 碲硼硅酸盐 热稳定性 高斯拟合 -基')" href="#">OH^-基     

Effect of Mn on the magnetic properties of Fe3B/Nd2Fe14B nanocomposites

The magnetic properties of Nd_4.5Fe_77−xMn_xB_18.5 (x=0, 1 and 2) nanocomposites prepared by the crystallization of amorphous precursors were investigated. Addition of Mn is found to decrease the crystallization temperature of the amorphous ribbons. The intrinsic coercivity _iH_c and maximum energy product (BH)_max increase from 2.6 kOe and 9.1 MGOe for x=0 to 3.1 kOe and 10.3 MGOe for x=1, respectively, and the remanence ratio M_r/M_s increases from 0.70 to 0.72. The effect of Mn on Curie temperature T_C and the thermal stability of M_r and _iH_c were also studied. ⁵⁷Fe Mössbauer spectra have been recorded for x=0, 1 and 2 ribbons at room temperature and site preference of the Mn atoms in Fe₃B and Nd₂Fe₁₄B phases is discussed using the Mössbauer spectroscopy.     

The glassy state of the amorphous V2O5–NiO–TeO2 samples

The glass transition temperature dependence to heating rate and therefore the activation energy (ΔH^?) of the glass transition of (60-x)V₂O₅–xNiO–40TeO₂ oxide glasses with 0≤x≤20 (in mol%) were investigated at heating rates φ (=3 6, 9, 10 and 12 K/min) using differential scanning calorimetry (DSC). The heating rate dependence of T_g was used to investigate the applicability of different theoretical models describing the glass transition. Using the application of Moynihan and Kissinger et al. models to the present data, different values of (ΔH^?) at each different heating-rate regions were obtained. The fragility parameter (m=ΔH^?/R T_g) was ∼24.98 for x=10 mol%, suggesting that this glass may be considered as a rather strong glass (fragility index m∼>20 is an indication of fragile glass). Also the compositional dependence of T_g and ΔH^? was investigated.     

Effect of compositional variation on the soft magnetic properties of Fe(87−x−y)CoxTi7 Zr6By amorphous ribbons

The effect of the replacement of Fe by Co or B on the thermal stability and soft magnetic properties of the Fe-based amorphous metallic ribbons with Fe_(87−x−y)Co_xTi₇Zr₆B_y (x = 10, 20% and y = 8, 10, 12%) produced by melt-spinning technique was investigated. For the melt-spun amorphous ribbons, the values of saturation magnetization and coercivity were observed to range from 107.00 to 152.38 emu/g and from 0.012 to 0.446 Oe, respectively. The thermal properties such as T_g, T_x, and ΔT_x were in the range of 796.7–809.6 K, 840.2–853.5 K, and 35.8–54.5 K, respectively. In the Fe–Co–Ti–Zr–B alloys, the Co substitution for Fe improved the soft magnetic properties but decreased the thermal stability. For magnetic properties, the coercivity (H_c) decreased and saturation magnetization (M_s) increased by the addition of Co. However, the supercooled liquid region (ΔT_x) decreased by the addition of Co. Meanwhile, the B substitution for Fe had no meaningful change on the thermal stability and soft magnetic properties. The amorphous ribbon of Fe₅₉Co₂₀Ti₇Zr₆B₈ exhibited the best soft magnetic properties such as the low coercivity of 0.025 Oe and the high saturation magnetization of 152.38 emu/g.     

Thermal stability and crystallization kinetics of Ge–Se–Cd glasses

The effect is reported of varying cadmium concentration on the glass transition, thermal stability and crystallization kinetics of Ge₂₀Se_{80? x} Cd _x (x = 2.5, 5, 7.5 and 10 at. %) glasses. Differential scanning calorimetry results under non-isothermal conditions for the studied glasses are reported and discussed. The values of the glass transition temperature (T_g ) and the peak temperature of crystallization (T_p ) were found to be dependent on heating rate and Cd content. From the heating rate dependence of T_g and T_p , the values of the activation energy for glass transition (E_g ) and the activation energy for crystallization (E_c ) were evaluated and their composition dependence discussed. The thermal stability of the glasses was evaluated using various thermal stability criteria such as ΔT, H_g and S. The stability calculations emphasize that the thermal stability decreases with increasing Cd content.     

IR and Raman investigation on the structure of (100-x)B2O3-x[0.5 BaO-0.5 ZnO] glasses

Glasses with molar composition of (100-x)B₂O₃-x[0.5 BaO-0.5 ZnO], x=40, 50, 60, 70 were prepared from the melts of ZnO, BaCO₃ and H₃BO₃ mixture. The structure and thermal behavior were characterized by IR and Raman spectroscopy, DSC and Dilatometer. The investigation shows that the transition of the structural unit [BO₄] (B^IV) to [BO₃] (B^III) happens when BaO and ZnO content x increases in the borate glass, resulting in fewer B^III-O-B^IV bonds and more B^III-O-B^III bonds. At the same time, the diborate groups, which are found to be the predominant structural group of the glass with high B₂O₃ content, gradually changes into ring-type metaborate, pyro- and orthoborate groups. With increasing ZnO and BaO content x, the glass transition temperature (T_g) and the softening point (T_f) decreases, while linear expansion coefficient (α) increases, that comes from the weakening of the glass network.     

Reactivity and XAFS study on (1−x)CeO2-xNiO (x=0.025-0.3) system in the two-step water-splitting reaction for solar H2 production

The redox reaction of Ce⁴⁺-Ce³⁺ promoted by the catalytic function of nickel ions in a (1−x)CeO₂-xNiO solid solution was investigated for solar H₂ production by the two-step water-splitting reaction. By irradiation using an infrared imaging lamp as a solar simulator, the O₂-releasing reaction with (1−x)CeO₂-xNiO solid solution proceeded at 1673-1873 K, and its reduced form was produced. The amounts of H₂ gas evolved by the reduced form were 1.2-2.5 cm³/g and the evolved gases amounts ratio of H₂/O₂ was nearly 2, which is equal to the stoichiometric value of the water-splitting reaction (H₂O=H₂+1/2O₂). The maximum amounts of evolved H₂ and O₂ gases were obtained at the Ce:Ni mole ratio of 0.95:0.05 (x=0.05) in the (1−x)CeO₂-xNiO system. The X-ray absorption fine structure (XAFS) measurement showed that the O₂-releasing and H₂-generation reactions with (1−x)CeO₂-xNiO solid solution were repeatable with the redox system of Ce⁴⁺-Ce³⁺, which was enhanced by the catalytic function of Ni²⁺-Ni⁰.     

Annealing effects on the bonding structures, optical and mechanical properties for radio frequency reactive sputtered germanium carbide films

The effects of thermal annealing in vacuum on the bonding structures, optical and mechanical properties for germanium carbide (Ge_1−xC_x) thin films, deposited by radio frequency (RF) reactive sputtering of pure Ge(1 1 1) target in a CH₄/Ar mixture discharge, are investigated. We find that there are no significant changes in the bonding structure of the films annealed below 300 °C. The fraction of Ge-H bonds for the film annealed at temperatures (T_a) above 300 °C decreases, whereas that of C-H bonds show a decrease only when T_a exceeds 400 °C. The out-diffusion of hydrogen promotes the formation of Ge-C bonds at T_a above 400 °C and thus leads to a substantial increase in the compressive stress and hardness for the film. The refractive indices and optical gaps for Ge_1−xC_x films are almost constant against T_a, which can be ascribed to the unchanged ratios of Ge/C and sp²-C/sp³-C concentrations. Furthermore, we also find that the excellent optical transmission for an antireflection Ge_1−xC_x double-layer film on ZnS substrate is still maintained after annealing at 700 °C.     

Influence of boron concentration on growth characteristic and electro-catalytic performance of boron-doped diamond electrodes prepared by direct current plasma chemical vapor deposition

A series of boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) with different compositions of CH₄/H₂/B(OCH₃)₃ gas mixture. A maximum growth rate of 0.65 mg cm⁻² h⁻¹ was obtained with CH₄/H₂/B(OCH₃)₃ radio of 4/190/10 and this growth condition was also a turning point for discharge plasma stability which arose from the addition of B(OCH₃)₃ that changed electron energy distribution and influenced the plasma reaction. The surface coating structure and electro-catalytic performance of the BDD electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Hall test, and electrochemical measurement and electro-catalytic oxidation in phenol solution. It is suggested that the boron doping level and the thermal stress in the films are the main factors affecting the electro-catalytic characteristics of the electrodes. Low boron doping level with CH₄/H₂/B(OCH₃)₃ ratio of 4/199/1 decreased the films electrical conductivity and its electro-catalytic activity. When the carrier concentration in the films reached around 10²⁰ cm⁻³ with CH₄/H₂/B(OCH₃)₃ ratio over a range of 4/195/5-4/185/15, the thermal stress in the films was the key reason that influenced the electro-catalytic activity of the electrodes for its effect on diamond lattice expansion. Therefore, the BDD electrode with modest CH₄/H₂/B(OCH₃)₃ ratio of 4/190/10 possessed the best phenol removal efficiency.     

Effects of Cr doping in bilayered manganite LaSr2Mn2O7: Resistivity, thermoelectric power, and thermal conductivity

Systematic studies of resistivity, thermoelectric power, and thermal conductivity have been performed on polycrystalline bilayered manganites LaSr₂Mn_2−xCr_xO₇ (0≤x≤0.2). It is found that the temperature dependence of both Seebeck coefficient S(T) and resistivity ρ(T) in the high temperature region follows the small polaron transport mechanism for all the samples. But in the low temperature region, variable-range-hopping (VRH) model matches the experimental data better. In addition, the maximum of absolute S(T) at low temperatures is gradually suppressed for the sample with Cr-doping level of x>0.04, implying that a new FM order probably arises. With decreasing the temperatures further, S(T) has a sign change and becomes positive for the sample with Cr-doping level of x>0.04, indicating that there may occur a variation of the type of charge carrier. As to thermal conduction κ(T), the low-temperature peak is suppressed due to Cr-doping. The variation of κ(T) is analyzed based on the combined effect due to the suppression of local Mn³⁺O₆ Jahn-Teller (JT) lattice distortion because of the substitution of Cr³⁺ ions for Mn³⁺ ions, which results in the increase in thermal conduction, and the introduction of the disorder due to Cr-doping, which contributes to the decrease in thermal conduction.