a-C:F薄膜的热稳定性与光学带隙的关联

以CF4和C6H6的混合气体作为气源,在微波电子回旋共振化学气相沉积(ECRCVD)装置中制备了氟化非晶碳薄膜(aC:F),并在N2气氛中作了退火处理以考察其热稳定性.通过傅里叶变换红外吸收谱和紫外可见光谱获得了薄膜中CC双键的相对含量和光学带隙,发现膜中CC键含量与光学带隙之间存在着密切的关联,在高微波功率下沉积的氟化非晶碳膜具有低的光学带隙和较好的热稳定性. 关键词： 氟化非晶碳膜 光学带隙 退火温度 热稳定性     

电子回旋共振等离子体增强沉积氟化非晶碳薄膜的光学性质

用紫外可见光透射光谱(UV-VIS)并结合键结构的X射线光电子能谱(XPS)和红外谱(FTIR)分析,研究了电子回旋共振等离子体增强化学气相沉积法制备的氟化非晶碳薄膜的光吸收和光学带隙性质.在微波功率为140—700W、源气体CHF₃∶C₆H₆比例为1∶1—10∶1条件下沉积的薄膜,光学带隙在1.76—2.85eV之间.薄膜中氟的引入对吸收边和光学带隙产生较大的影响,吸收边随氟含量的提高而增大,光学带隙则主要取决于CF键的含量,是由于强电负 关键词： 氟化非晶碳薄膜 光吸收与光学带隙 电子回旋共振等离子体     

源气体对沉积的a-C∶F∶H薄膜结构的影响

采用微波电子回旋共振等离子体化学气相沉积(MWPECRCVD)方法,使用不同的源气体(CHF3CH4,CHF3C2H2,CHF3C6H6)体系制备了aC∶F∶H薄膜.由于CH4,C2H2,C6H6气体在等离子体中的分解反应不同导致了薄膜的沉积速率和结构上的差异.红外吸收谱的结果表明,用C6H6CHF3作为源气体沉积的薄膜中几乎不含H,而用C2H2CHF3所沉积的薄膜中的含氟量最高,其相应的CF振动峰位向高频方向偏移.薄膜的真空退火结果表明,aC∶F∶H薄膜的热稳定性除了取决于薄膜的CC键浓度外,还与CC键 关键词： 氟化非晶碳膜 电子回旋共振化学气相沉积 红外吸收光谱     

真空退火对氟化非晶碳薄膜结构的影响

在苯(C6H6)和四氟化碳(CF4)混合气体中,用微波电子回旋共振等离子体化学气相沉积技术(ECRCVD)在不同功率下制备了氟化非晶碳膜(aC:F),为了检测膜的热稳定性对其进行了真空退火处理,测量了退火前后膜厚的变化率,并用傅里叶变换红外吸收光谱(FTIR)研究了其结构的变化.结果表明,膜厚变化率与沉积功率有关;400℃退火后低功率下沉积的膜的结构变化显著,高功率下沉积的膜则呈现了较好的热稳定性. 关键词： ECR-CVD aC:F薄膜 真空退火     

微波输入功率引起a-C∶F薄膜交联结构的增强

使用C2H2和CHF3的混合气体,在改变微波功率的条件下,利用微波电子回旋共振等离子体增强化学气相沉积方法制备了氟化非晶碳薄膜(aC∶F).薄膜的傅里叶变换红外光谱分析结果表明:薄膜中的CC与C—F键含量的比值随功率的增加而相应地增大;借助于紫外可见光谱分析发现,薄膜的光学带隙随功率的增大而减小.由此推断微波输入功率的提高有助于增强薄膜的交联结构.aC∶F薄膜的交流电导与x射线光电子能谱进一步证实了这种增强效应 关键词： 氟化非晶碳薄膜 傅里叶变换红外光谱 x射线光电子能谱     

微波电子回旋共振-化学气相沉积SiN_x薄膜的光学性能研究

研究了微波电子回旋共振－化学气相沉积ＳｉＮｘ薄膜的光学性能，这种ＳｉＮｘ薄膜具有透光谱宽、透光率高的特点，总结了透光谱、折射率、光隙能随微波功率、基片温度的变化关系     

微波电子回旋共振—化学气相沉只SiNx薄膜的光学性能研究

研究了微波电子回旋共振－化学气相沉积ＳｉＮｘ薄膜的光学性能，这种ＳｉＮｘ薄膜具有透光谱宽，透光率高的特点，总结了透光谱，折射率，光隙能随微波功率，基片温度的变化关系。     

不同CHF_3/CH_4流量比下沉积a-C∶F∶H薄膜键结构的红外分析

通过微波电子回旋共振等离子体化学气相沉积方法使用CH4 CHF3源气体制备a C∶F∶H薄膜 .红外结果表明 ,a C∶F∶H薄膜随着流量比R =[CHF3] [CHF3] [CH4])的变化存在结构上的演变 ,R <6 4%时 ,薄膜主要是以类金刚石 (DLC)特征的结构为主 ;当R >6 4%时 ,薄膜表现为一个类聚四氟乙烯 (PTFE)的结构 ,结构单体主要为 CF2 .同时这种结构上的变化影响着薄膜的光学带隙 .在类DLC特征结构区 ,Eg 随着流量比的增加而下降 ,而在类PTFE区 ,Eg 则随着流量比的上升而上升 .a C∶F∶H薄膜在R >92 %时透射率接近 10 0 %     

用H-W-ECR CVD系统实现氢化非晶硅薄膜在氢气环境下同时进行化学热退火和光诱导退火的研究

为了研究氢化非晶硅薄膜的稳定性，我们设计了一个在原子氢气氛中热退火的同时进行光诱导退火的实验(TLAH)。实验装置是由传统的微波电子回旋共振化学气相沉积系统改造而成为热丝辅助微波电子回旋共振化学气相沉积系统。为了对这一退火方法进行比较，对样品还进行了热退火、热退火同时进行光诱导退火。同时，为了定量地分析光电导衰退，我们假设光电导衰退遵循扩展指数规律：1/σph=1/σs-(1/σs-1/σ0)exp[-(t/τ)β]，这里扩展指数参数β 和时间常数 τ 可从与 lnt 的线性关系中截距和斜率得到, 式中光电导饱和值σs可以通过在对数坐标系中表示的光电导和光照时间关系进行高斯拟合得到。实验结果显示：TLAH 方法可以提高氢化非晶硅薄膜的稳定性、改善其微结构和光电特性，同时还发现，光学带隙明显减小、荧光光谱显著地朝着低能方向移动。     

ECR-CVD制备的非晶SiOxNy薄膜的光致蓝光发射

使用90%N2稀释的SiH4与O2作为前驱气体，利用微波电子回旋共振等离子体化学气相沉积（ECR CVD）方法制备了非晶氮氧化硅薄膜（a-SiOxNy）.红外吸收光谱的结果表明，a SiOxNy薄膜主要由Si O Si和Si N键的两相结构组成，在存在氧流量的情形下，薄膜主要成分是SiOx相，而在无氧流量的情形下，薄膜则主要是SiNx相.使用565eV的紫外光激发，发现SiOxNy薄膜出现了位于460nm的光致蓝光主峰，且其发光强度随着氧流量的降低而显著增强.根据缺陷态发光中心和SiNx蓝光发射能隙态模 关键词： ECR CVD 红外吸收光谱 非晶氮化硅薄膜 光致发光     

铕取代的锆硼钨多金属氧酸盐的制备和发光特性

制备了高发射效率的稀土多金属氧酸盐BPOM:Eu及ZrPOM:Eu荧光体,并对其结构及发光性质进行了研究。结果表明样品具有Keggin结构,Eu在两类样品中均有肉眼可见的在红光区的强发射。但在BPOM:Eu中以⁵D₀→⁷F₁磁偶极跃迁发射为主,在ZrPOM:Eu中以⁵D₀→⁷F₂电偶极跃迁发射为主。铕在ZrPOM:Eu中的对称性低于在BPOM:Eu中的对称性。这种差异也使铕离子的激发光谱具有不同的特征。铕在两种多金属氧酸盐中均有浓度猝灭,在BPOM:Eu中浓度为2.0%时发射强度最大;在ZrPOM:Eu中浓度为2.4%时发射强度最大。在ZrPOM:Eu中有较弱的配体到中心铕离子的能量传递,而在BPOM:Eu中却未观测到能量传递现象。     

Pressure–temperature studies on conductivity of TlX(X=Cl,Br,I) compounds:: I: phase diagram. II: ionic mobility

We have measured the conductivity σ of TlX(X=Cl, Br, I) compounds up to 5.3 GPa and between 300–823 K. The σ–T dependence for all compounds can be divided into three distinct regions: (i) low temperature (LT), <400 K, with unusual negative σ–T dependence, (ii) intermediate temperature (IT), 400<650 K, with positive σ–T dependence and (iii) high temperature (HT), T>650 K, with positive σ–T dependence. The σ–T isobars were used to construct the T–P solid phase diagram for each compound. The LT region data indicate a new meta-stable phase in the 1.0–3.5 GPa range. The LT→IT transition is characterized by an inverse σ–T dependence followed by normal Arrhenius behavior up to and including the HT region. The extrapolation to 1 atm of the P-dependent boundary between IT and HT regions above 3 GPa for each compound in the P–T plot yields a value close to its respective normal (1 atm) T_melt suggesting a solid order–disorder transition type paralleling -AgI behavior. The abrupt drop in conductivity in the LT region for P between 2.5–4.1 GPa of all compounds is at variance with the Arrhenius behavior observed for unperturbed ion migration implying the appearance of a second factor overriding the Arrhenius temperature dependence. Normal Arrhenius σ–T dependence prevails in both IT and HT regions with Q_c values of 85–100 kJ mol⁻¹ and 50–75 kJ mol⁻¹, respectively. The higher conductivities at 0.4 GPa for TlBr and TlI relative to their 1 atm data and the increasing σ with P are in strong contrast to the normal σ-P behavior of TlCl. The dependence of activation volume ΔV^‡ on T for TlCl, i.e. ΔV^‡>0, shows abnormally high values with a maximum at 500 K for P<3.0 GPa but reasonable ΔV^‡ values appear above 3.0 GPa. The ΔV^‡–T dependence for both TlBr and TlI with ΔV^‡<0 is incompatible with an ion transport mechanism suggesting an electronic conduction process and implying an ionic–metallic transition at higher pressures. These contrasting conductivity features are discussed and interpreted in terms of electronegativity differences and bonding character rather than structure.     

Investigation of nonvolatile holographic storage in LiNbO3:Mn:Ce:Fe crystal

We investigate the persistent holographic recording in triply doped LiNbO₃:Mn:Ce:Fe crystals at different oxidation/reduction states. The experimental results show that there is an optimum oxidation/reduction state, which results in the best dynamic range M/#. Compared with doubly doped LiNbO₃:Ce:Fe, we found that the nonvolatile diffraction efficiency and the best dynamic range M/# obtained in triply doped samples are larger than that obtained in doubly doped samples. The reason for the increase of the crystal about the nonvolatile diffraction efficiency and the dynamic range M/# was also explained.     

Aerodynamic Measurements: Normative Data for Children Ages 6:0 to 10:11 Years

Normative measures of open quotient, speed quotient, maximum flow declination rate (MFDR), and subglottal pressure were determined for 75 children between the ages of 6 years 0 months and 10 years 11 months. The participants produced a sustained /a/ at low, comfort, and high pitches for a minimum of 5 seconds, and five to seven repetitions of /pa/ at low, comfort, and high pitches. No statistically significant differences were found in the mean measures of any aerodynamic variables (open quotient, speed quotient, maximum flow declination rate, subglottal pressure) between the frequency levels (low, comfort, high pitches). Also, no strong evidence (P > .05) exists that age or sex effect differed between the frequency levels (low, comfort, high) for any of the aerodynamic measures. For /a/ response tasks, mean open quotient measures increased slightly from low to comfort frequency and from comfort to high frequency. Mean speed quotient measures showed minimal differences between low and comfort frequency, with decreased mean measures for high frequency. Mean MFDR measures increased from low to comfort frequency and from comfort to high frequency. Mean subglottal pressure measures increased slightly from low to comfort frequency and from comfort to high frequency.     

125-TW Ti:sapphire/Nd:glass laser system

We have demonstrated a Ti:sapphire/Nd:glass laser system that produces up to 51 J of energy in 395-fs pulses (125TW). Focusing at f/3 to a 2.5-times diffraction-limited spot results in a peak irradiance greater than 10(20) W/cm(2) . Our 40-cm-diameter gold diffraction gratings have a damage threshold of 0.42 J/cm(2) for 320-fs pulses.     

Nanoparticle Opportunities:

Major advances in understanding aerosol formation and growth allow now production of nanoparticles with closely controlled characteristics so that some of the early promises of nanotechnology are materialized. The production of flame‐made titania particles coated in‐situ with vanadia was brought from a microreactor (4 g/h) to a pilot‐scale reactor (up to 200 g/h). Corresponding mixtures of titanium‐ and vanadium‐alkoxides were evaporated into a nitrogen or hydrogen stream and fed into a turbulent hydrogen/air or hydrogen/oxygen flame using a commercial burner. By controlling gas flow rates, burner configuration and type of oxidant, particles with a wide range of characteristics were made. Rutile rich (>85 wt%) to pure anatase (>99.5 wt%) powders were made by exchanging air with oxygen. Vanadia/titania catalysts were made with up to 10 wt% V₂O₅ and were compared to powders made in the flame microreactor. A representative flame‐made DeNOx catalyst exhibited twice as much activity as a conventionally prepared reference catalyst for the removal of NO from a model exhaust gas by selective catalytic reduction with ammonia.