含ZrF4氟铝酸盐玻璃研究

以10MgF_2-20CaF_2-10SrF_2-10BaF_2-15YF_3-35AlF_3(摩尔百分数)氟铝酸盐玻璃为基本组成,在玻璃中引入不同含量的ZrF_4,同时对其它组成进行适当调整,制得了厚度8mm无可见析晶的氟化物玻璃。利用差热分析(DTA)技术研究了ZrF_4对玻璃形成能力和玻璃析晶动力学的影响,结果表明,少量的ZrF_4可以提高玻璃的抗失透能力,过量的ZrF_4会降低玻璃形成能力;ZrF_4的最佳含量范围为7.3～11.4mol％。根据测得的玻璃的红外透过光谱显示,该玻璃具有良好的透红外光性能。     

Propagation losses and gain measurements in erbium-doped fluoride glass channel waveguides by use of a double-pass technique

We have studied Er3+, Yb3+, and Ce3+ codoped microchannel waveguides that were developed by two methods: ionic exchange for heavy metal fluoride glasses [ZrF4-BaF2-AlF3-CeF3 (ZBAC)] and vapor phase deposition for transition metal fluoride glasses [PbF2-ZnF2-GaF3 (PZG)] by using a double-pass technique. For the first time to our knowledge, the measurement of propagation losses and amplification tests were carried out by use of the same experimental setup, leading to complete characterization of the waveguides. Net gains higher than 1 dB/cm were achieved in ZBAC Er/Ce single-mode fluoride glass waveguides.     

含AlF3和ZrF4氟化物玻璃的分相与析晶

以摩尔组成为8．7MgF2-17．4CaF2-8．7SrF2-13．3BaF2-13．0YF3-31．6．AlF3-7．3ZrF4的氟化物玻璃为对象，研究了玻璃的分相和析晶．研究表明，玻璃中同时含有AlF3和ZrF4时，玻璃产生明显的分相，玻璃在高温下对水比较敏感，容易产生表面析晶．玻璃内部的析晶主要来自稳定性较差的富Al相，受空气中水分的影响，玻璃表面的析晶首先产生于富Zr相．依据玻璃的分相和析晶表现，讨论了含AlF3和ZrF4氟化物玻璃的表面析晶机理．     

Sol-gel-based, planar waveguide sensor for gaseous iodine

A novel sensor for gaseous iodine has been developed using a combination of sol-gel processing and planar integrated optical waveguiding technologies. The sensing principle is based on the detection of a charge transfer complex formed between iodine and phenyl groups that have been incorporated into a porous, methylated glass film. The glass film was prepared from siloxane precursors by the sol-gel method. Sensors were fabricated by coating the film over a single-mode planar waveguide. Light was coupled into and out of the laminate structure using integral grating couplers, and formation of the charge transfer complex was monitored as attenuated total reflection of the guided wave. The sensor exhibits a linear response to I(2) in the range of 100 ppb to 15 ppm with response and recovery times less than 15 s. The response is selective to 4 ppm iodine in the presence of 10 ppm chlorine and is stable for at least 3 months.     

Spectroelectrochemical sensing based on multimode selectivity simultaneously achievable in a single device. 9. Incorporation of planar waveguide technology

Incorporation of planar waveguide technology into a spectroelectrochemical sensor is described. In this sensor design, a potassium ion-exchanged BK7 glass waveguide was over-coated with a thin film of indium tin oxide (ITO) that served as an optically transparent electrode. A chemically selective film was spin-coated on top of the ITO film. The sensor supported five optical modes at 442 nm and three at 633 nm. Investigations on the impact of the ITO film on the optical properties of the waveguide and on the spectroelectrochemical performance of the sensor are reported. Sensing was based on the change in attenuation of light propagated through the waveguide resulting from an optically absorbing analyte. By applying either a triangular or square wave excitation potential waveform, electromodulation of the optical signal has been demonstrated with Fe(CN)6(3-/4-) as a model electroactive couple that partitions into a PDMDAAC-SiO2 film [where PDMDAAC = poly(dimethyldiallylammonium chloride)] and absorbs at 442 nm.     

Influence of fluorescence reabsorption and trapping on solid-state optical cooling

We analyze the random process of fluorescence reabsorption and trapping in solid-state optical materials in general and its influence on the efficiency of optical cooling of solids by anti-Stokes fluorescence in particular. Using the absorption and fluorescence spectra of Yb3+:ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) as input data, we employ a random-walk model to test analytical approximations of the fluorescence escape efficiency and cooling efficiency, including reflections at the boundary.     

Enhanced ultraviolet upconversion luminescence of Tm and Yb codoped ZrF4-BaF2-LaF3-AlF3-NaF glass

Ultraviolet (UV) upconversion (UC) luminescence properties of Tm3+ ions sensitized by Yb3+ ions in ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass were studied in detail. Under the excitation from a 980 nm continuous wave (CW) diode laser, red, blue, and even UV emissions were observed in the fluorozirconate glass. Several fluorescence bands appeared in the UC emission spectrum from 292.8 nm to 805.8 nm. The UC emission peaks at 291 nm, 347 nm, 363 nm, 454 nm, 475 nm, 647 nm, 687 nm, and 804 nm correspond to the transitions of 1I6 --> 3H6, 1I6 --> 3F4, 1D2 --> 3H6, 1D2 --> 3F4, 1G4 --> 3H6, 1G4 --> 3F4, 3F3 --> 3H6, and 3H4 --> 3H6, respectively. Experimental results of intensity dependence of the up-converted fluorescence on the pump power indicate a five-photon excitation scheme of 1I6 energy level.     

Silicon-to-indium tin oxide coated glass bonding for packaging of field emission arrays fabricated on silicon wafer

A silicon-to-In₂O₃:Sn coated glass bonding has been developed for the package of field emission arrays fabricated on the silicon wafer, utilizing a conventional silicon-to- silicon anodic bonding using the glass layer. A 1.8 m Pyrex #7740 glass layer was deposited on the In₂O₃:Sn coated glass by an electron beam evaporation. It was confirmed that the composition of the glass layer was nearly the same as that of the bulk Pyrex #7740 glass plate. In this work, bonding the silicon and In₂O₃:Sn coated glass was achieved at a temperature of 190 °C with an applied voltage of 60 V_dc. A secondary ion mass spectroscopy analysis was used to confirm the modeled bonding kinetics of the silicon-to-In₂O₃:Sn coated glass.     

Pulsed laser deposited ZnO film on side-polished fiber as a gas sensing element

A simple sensor element consisting of a side-polished single-mode fiber and a planar metal oxide waveguide is described. The thin ZnO planar waveguide was produced on the polished fiber surface by pulsed laser deposition at optimized processing parameters. A measurement scheme for in situ control of the film thickness during the deposition process was developed and used. X-ray diffraction measurements and scanning electron microscopy were used to characterize the structure and the surface morphology of the planar waveguide, respectively. The numerical evaluation of the sensor sensitivity predicts the possibility to detect refractive index changes of less than 10(-4). Furthermore, preliminary gas sensor tests were performed by using a mixture of 1.5% butane diluted in N(2) and pure butane. A shift of the spectral position of the resonance points was observed from 3 to 5 s after gas exposure, which corresponds to refractive index changes of 3 x 10(-5) and 1.2 x 10(-3) for 1.5% butane and for pure butane, respectively.     

Thermal analysis of glasses in TeO2-BaF2-LaF3 systems

Divalent metal fluorides MF2 （M=Sr, Mg, Ca） in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides-MF2（M=Sr, Mg, Ca） on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.     

Thick film adherence fracture energy: influence of alumina substrates

The adherence of a glass bonded Pt-Au thick film conductor to various alumina substrates is degraded by changes in the surface composition of and by the presence of (0001) crystallographic texture in the substrate. Using the critical fracture energy (γ_IC) required to separate the thick film from the substrate, it was found that γ_IC was reduced from a maximum of 3.7 J m⁻² using an as-received 96+ wt% alumina substrate to ∼2J m⁻² using an as-received 99+ wt% alumina. In addition, the thick film adherence γ_IC using (0001) sapphire substrates was less than that using (11ˉ23) sapphire. The 96 wt% substate exhibited essentially a random crystallographic surface texture and a considerable amount of surface silicates. The as-received 99+ wt% Al₂O₃ substrate was charactarized by a high (0001) surface texture and, while exhibiting a similar composition silicate layer as that of the as-received 96 wt% alumina, the total amount of the glass layer is greatly diminished. Fractographic analysis of the separated thick films and substrates showed that changes in the substrate crystallographic texture and the glass layer diminish the interpenetrating nature of the glass—metal interface and weaken the glass—substrate interface. Such changes in thick film microstructure lead to poorer thick film adherence.     

Na_2ZrF_6掺杂硅烷膜的成膜过程及其耐腐蚀性能研究

为了提高钢材表面硅烷膜的耐腐蚀性,在硅烷液中加入Na_2ZrF_6,在40Cr钢表面制备了掺杂Na_2ZrF_6的硅烷膜。采用电化学法和失重法分析了Na_2ZrF_6掺杂硅烷膜的耐蚀性,采用光学显微镜和扫描电镜观察掺杂硅烷膜的形貌,采用傅立叶红外光谱仪分析了Na_2ZrF_6掺杂硅烷液的特征峰,采用X射线光电子能谱仪分析了掺杂硅烷膜的元素价态及结合能;研究了Na_2ZrF_6掺杂对硅烷成膜性及耐蚀性能的影响。结果表明:硅烷液中Na_2ZrF_6的添加量为0.001 mol/L时,40Cr钢表面的掺杂硅烷膜性能最好;Na_2ZrF_6掺杂硅烷膜表面致密,其表面存在一些微小球状颗粒,且存在掺杂的Zr元素;掺杂硅烷膜能够有效提高40Cr钢的耐腐蚀性;掺杂硅烷膜以表面的Zr元素形成的化合物来阻碍阳极活性区溶解,提高了40Cr钢的耐蚀性。     

Tb3+-Yb3+共掺氟氧化物微晶玻璃的发光特性及其外量子效率的评价

本研究制备了Tb3+-Yb3+共掺杂含CaF2纳米晶相的氟氧化物透明微晶玻璃,并通过XRD验证了CaF2纳米晶的形成。基于Tb3+对Yb3+的协同能量传递,通过激发Tb3+∶5D4能级可观察到由Yb3+∶2F5/2→2F7/2跃迁引起的950~1100nm近红外发射。利用积分球测试系统评价了Yb3+在玻璃及微晶玻璃体系中的外量子效率,数据表明经过热处理后Yb3+的外量子效率有明显的增加,这是由于在微晶玻璃体系中掺杂的Tb3+离子和Yb3+离子富集在具有低声子能量的CaF2晶相从而获得了更有效的能量传递而引起的。同时利用Tb3+荧光寿命计算获得了材料的内量子效率,其值远大于外量子效率,这是由计算过程中的诸多近似所导致。     

CdF2-BaF2-LiF系统玻璃的X射线衍射与分子动力学研究

采用无水氟化物直接熔化法得到了CdF2－BaF2－LiF系统玻璃的玻璃形成区，用X射线衍射和分子动力学计算机结构模拟等手段研究了成分为36CdF2－34BaF2－30LiF（mol％）的玻璃的结构．研究表明，Cd原子主要为6、7和8配位，Ba原子主要为8配位，Cd－F的平均键长为2.29玻璃结构可以看作是由Li 连接的[CdF72]多面体共边或共角堆积而成．Cd－Cd键长在共边连接时为3.52共角时为4.03对氟化物玻璃中Li 原子所起的作用进行了比较．     

一种组成的CaF2-Al2O3-SiO2系玻璃结构研究

使用DTA、IR光谱、Raman光谱、光电子能谱、XRD、SEM和EDAX等分析方法研究了一种组成的CaF2-Al2O3-SiO2系玻璃的结构，发现玻璃的结构是由［SiO4］和［AlO4］以顶角相连的方式构成基本网络骨架，Ca2＋处于网络间隙，F-有一部分取代O2-进入玻璃网络，另一部分停留在网络间隙，Al3＋也有一部分处于网络间隙．F-取代O2-进入玻璃网络，削弱了玻璃的网络结构，使玻璃发生了分相，其中一相富含Si4＋和Al3＋，另一相富含Ca2＋和F-，热处理时，CaF2晶体首先从这一相中析出．     

Hydroxyapatite films on silicon single crystals by a solution technique: texture,supersaturation and pH dependence

Thick films of hydroxyapatite (HA) were deposited on silicon single crystal wafers placed in close proximity to a plate of apatite- and wollastonite-containing glass and dipped into a simulated physiological solution at 36°C. Amorphous calcium phosphate phase present in the glass leached into the solution, causing supersaturation of Ca²⁺ and PO₄ ^3- ions. Spherical cap-like islands of calcium phosphate nucleated on Si crystals and grew in size with time. The thickness of the film grown on Si (111) in a solution having a composition similar to that of human blood plasma, and maintained at pH of 7.2, reached 7.1 m in 336 h, compared with a thickness of 12.7 m when the ion concentrations of the solution were doubled. HA films grown on Si (111) showed strong (102) texture. In contrast, hardly any HA film could be grown on Si (100). With increasing pH value of the solution the Ca/P ratio of the film increased. At a pH of 7.2 the as-grown and annealed (at 800°C for 3 h in argon) films had Ca/P ratios of 1.10 and 1.72, respectively. The Vickers hardness and the adhesion strength of the film increased upon annealing. Our results suggest that the driving force for formation of apatite films arises from the lowering of free energy of the supersaturated solution by deposition of ions (Ca, P, O, H) in certain crystallographic arrangements on suitable substrates with low interface energies.     

Preparation of spinel-type ferrite thin films by the dip-coating process and their magnetic properties

Films of spinel-type ferrite, MFe₂O₄ (M=Ni, Co, Mg, Li_0.5Fe_0.5) have been prepared by a dip-coating method from the sol-gel process. Ferric nitrate, nickel nitrate, cobalt nitrate and lithium nitrate were used as raw materials, and glycerol and formamide were used as solvents. A film was prepared by dipping a silica glass plate. The spinel-type ferrite was obtained by heat-treatment at 700–900°C for 2 h in air. The film thickness was about 0.8 m. The saturation magnetization, _r, of the film and powder with composition 50NiO·50Fe₂O₃ was 196 emu cm^–3 and 29.1 emu g^–1, respectively, and the coercive force,H _c, was 140 and 95 Oe, respectively, after heat-treatment at 800°C for 2 h. In particular, the films were shown to have a much largerH _c than the powder. The grain growth of spinel ferrite may be subject to restriction because it is in progress above an amorphous base-plate. The crystals are therefore aligned with the base-plate and have uniaxial anisotropy.     

Planar Optical Waveguide Evanescent Wave ${rm CO}_{2}$ Sensor Based on a Clad of Alstonia Scholaris Leaf Extract

An evanescent wave biosensor is designed and developed using a single mode planar optical waveguide based on a spin coated clad of leaf extract of Alstonia Scholaris. The fabricated sensor showed ${rm CO}_{2}$ concentration dependent response. The specialty of this sensor is that it can be used when stored at room temperature (25$~^{circ}{rm C}$) up to a maximum of 25–30 days with 90% retention of original sensitivity. These ${rm CO}_{2}$ sensing biochips showed good operational efficiency for 10 cycles. The planar optical waveguide is versatile, easy to fabricate and can be used for ppm level ${rm CO}_{2}$ measurement with good sensitivity. Cross sensitivity with respect to humidity is studied. The sensor exhibited a short response time of 4–5 s and recovery time of 25 s with good repeatability and reproducibility.      

Fabrication, characterisation and application of (8 mol% Y2O3) ZrO2 thin film on Na3Zr2Si2PO12 substrate for sensing CO2 gas

A planar type CO₂ gas sensor employing (8 mol% Y₂O₃) ZrO₂ (YSZ) thin film on Na₃Zr₂Si₂PO₁₂ (Nasicon) substrate with Na₂CO₃ as an auxiliary electrode has been fabricated and tested in laboratory environment between 700–900 K. The YSZ thin film was fabricated on Nasicon and alumina substrate using radio frequency (RF) magnetron sputtering. The film was examined using SEM and X-ray diffraction (XRD) after treating the Nasicon-YSZ bi-layer structure at 1300 K for 2 h. The results indicate that a crack free YSZ film was produced on Nasicon surface that was well bonded to the substrate. The conductivity of sputtered YSZ thin film measured by ac-impedance spectroscopy has been found to be higher than that of YSZ pellet by approximately half an order of magniture. The bi-electrolyte planar sensor displays rapid response (t₉₅ 200 s) to CO₂ compared to the tube type sensor (t₉₅ 700 s) and the measured open circuit voltage of the electrochemical CO₂ sensor has been found to be Nernstian at all temperatures.     

Refractive-index dispersion for BaF2-GdF3-ZrF4-AlF3 glasses

Refractive-index dispersion measurements were performed on bulk specimens of 2-, 4-, or 6-mol % AlF(3) doped 33BaF(2)-4GdF(3)-63ZrF(4) (mol %) glass and 4-mol % LiF, CsF, YF(3), CdF(2), SnF(2), or PbF(2) doped 31.68BaF(2)-3.84GdF(3)-60.48ZrF(4)-4AIF(3) (mol %) glass in the wavelength region from 0.4047 to 5.3036 microm. The material dispersion curve and zero material dispersion wavelength were estimated on the basis of refractive- index dispersion measurements. The slope of the material dispersion curve for these fluoride glasses was less steep than that for SiO2 glass in the wavelength range estimated. The zero material wavelength lambda(0) shifted to a shorter wavelength with increasing AlF3 concentration. The lambda(0) is 1.675 microm for 31.68BaF(2)- 3.84GdF(3)-60.48ZrF(4)-4AlF(3) (mol %) glass. When 4-mol % LiF, CsF, YF(3), CdF(2), SnF(2), or PbF(2) were doped into these glasses, each lambda(0) shifted from 1.675 to 1.670, 1.668, 1.673, 1.681, 1.683, or 1.704 microm, respectively. The temperature dependence values of the refractive-index dispersion and material dispersion for 31.68BaF(2)-3.84GdF(3) -60.48ZrF(4)-4AIF(3) (mol %) glass were also obtained. The temperature coefficients of the refractive index were negative values (dn/dT(relative) = -1.0 X 10(-5)/degrees C) and the wavelength dependence of dn/dT was small. The wavelength lambda(0) shifted from 1.675 to 1.605 microm, due to the rise in the measurement temperature from 25 degrees C to 250 degrees C.