Processing and characterization of transparent TeO2-Bi2O3-ZnO glass ceramics

Fabrication of TeO₂-Bi₂O₃-ZnO glass ceramics with high transmittance in the near infrared (NIR) region is reported in the present work. Transparent tetragonal bipyramid crystals, tens of micrometers in size, with a refractive index closely matched to that of the glass matrix were formed using a two-step heat treatment. Nucleation- and growth-like curves for this crystal phase were determined using Differential Scanning Calorimetry (DSC). The crystalline phases present in the glass ceramics were identified via x-ray diffraction as a function of heat treatment. The lowest absorption coefficient of glass ceramic is approximately 0.5/cm in the near infrared region (1.2 to 2.8 μm).     

Optical and spectroscopic properties of germanotellurite glasses

In this work, new glass compositions in the TeO₂-GeO₂-Nb₂O₅-K₂O system have been prepared and studied. The germanotellurite glasses were prepared by melt-quenching and their density, refractive index and characteristic temperatures have been determined. The structure of these glasses has been studied by infrared and Raman spectroscopies.The progressive replacement of TeO₂ by GeO₂ led to an increase of the glass transition and crystallisation temperatures of the glasses and a simultaneous decrease of their density and refractive index. Typical density and refractive index values of these glasses ranged from 4.98 to 3.85 g cm^− 3 and 2.08 to 1.79, respectively, with increasing GeO₂ content. The infrared spectra are dominated by a band ~ 640 cm^− 1 in the tellurite glass and ~ 800 cm^− 1 in the germanate glass. The Raman spectra of the germanotellurite glasses present an intense boson peak between ~ 34 and 47 cm^− 1, together with high frequency peaks at ~ 670 cm^− 1 and ~ 470 cm^− 1 for high tellurite and high germanate glass compositions, respectively. The vibrational spectra of these germanotellurite glasses indicate that the glass network consists basically of TeO₄ and [TeO₃]/[TeO_3 + 1] units, mixed with GeO₄ and NbO₆ polyhedra.     

Structural study of sol-gel silicate glasses by IR and Raman spectroscopies

A study of the structure and bonding configuration of sol-gel silicate glasses by Raman and infrared spectroscopies is presented. Moreover, a review of the Raman lines and infrared bands assignment, the identification of the non-bridging silicon-oxygen groups and the ring structures are also demonstrated. The evolution of the changes of the bonding configuration in the composition and the stabilization temperature of the bioactive glasses is discussed in terms of the structural and textural characteristics of the glasses. Raman and infrared analyses contribute to the improvement in understanding of the local symmetry for sol-gel silicate glasses. infrared spectroscopy has allowed to identify the vibration bands of the hydroxyl groups associated with various configurations of the terminal silanol bonds on the glass surface and the free molecular water in the glass matrix. Raman analysis has provided an alternative method of quantifying the network connectivity grade and predicting the textural properties of the sol-gel silicate glasses.     

Slow dynamics of liquid Se studied by Infrared Photon Correlation Spectroscopy

We report on the study of the slow dynamics of supercooled and molten Selenium by means of dynamic light scattering. To achieve this in the present case, where the opaqueness of Se prevents visible light scattering measurements, we have developed a novel experimental setup using infrared radiation as the light source. By measuring the scattered intensity autocorrelation function we have been able to extract the average size of the Se clusters in the liquid state and determine the temperature dependence of the related diffusion coefficient which was found to exhibit Arrhenius behavior.     

基于锑化物二类超晶格的多色红外探测器研究进展

近年来InAs/GaSb二类超晶格红外探测器在材料晶体结构生长、器件结构设计与成像应用方面取得了飞速发展。尤其在多色红外探测方面,二类超晶格材料以其具备的带隙可调、暗电流小、量子效率高、材料均匀性高,以及成本低等优越性能,使其逐步成为第三代红外焦平面探测器的优选材料。本文阐述了锑化物窄带隙半导体研究中心的锑化物多色红外探测器研究进展。本团队成功实现了低噪声、高量子效率以及低光学串扰的短/中、短/长、中/长、长/长、中/长/甚长波等多种高性能多色红外探测器研制。     

高温高速流场条件下蓝宝石材料对红外成像影响分析

蓝宝石是一种性能优良的红外窗口材料,文章结合某高速飞行器应用要求设计了高温高速流场条件下蓝宝石对红外成像影响试验,分析了蓝宝石对红外成像影响结果,提出了对各种影响的校正方法,为高速飞行器红外成像制导技术应用研究提供了技术基础.     

Optical properties of chalcogenide multilayer deposited on Au layer

The chalcogenide multilayers were prepared as dielectric mirrors having the first order stop bands in the near infrared region 1.55 μm. The 7.5 layer pairs of the alternating amorphous Sb–Se and As–S layers were deposited on glass substrates using a conventional thermal evaporation method. To center the stop bands of the 15-layer dielectric mirrors at 1.55 μm, the layer thicknesses 117 nm for Sb–Se and 169 nm for As–S single layers were calculated from the quarter wave stack condition. The optical reflection and transmission spectra of the prepared mirrors were measured using a UV/VIS/NIR and FT-IR spectroscopy at the ambient and elevated temperatures. The optical reflection of the annealed 15-layer chalcogenide mirror was found higher than 99% in the range of 1440–1600 nm. As the 200 nm thick gold layer was added between the substrate and the chalcogenide mirror, the stop band of the annealed Au/multilayer system broadened to 1360–1740 nm simultaneously with an appearance of the 15% transmission peak at 1.55 μm. A preparation of similar metal/multilayer systems is one of the possible ways how to design the dielectric filters for near infrared region exploiting the good optical quality of the chalcogenide films and their simple deposition.     

Zn3BPO7晶体的THz和红外吸收光谱

本文研究了Zn3BPO7(ZBP)晶体的THz时域光谱以及从中红外到远红外的吸收光谱,以及6.6 cm-1 (0.2 THz)～4000 cm-1宽频段的红外光谱光学性质.THz吸收光谱表明晶体在0.5～1.2 THz有较好的透射性质,在1.7 THz和2.5 THz分别存在一个泛频共振峰和基频共振峰,并且折射率稳定.在远红外区(100～2700 cm-1)晶体的透射率极小,几乎接近于零.在中红外波段(2700～4000 cm-1)晶体具有较好的透射性质.50～4000 cm-1波段的吸收规律表明ZBP晶体具有做成特定波段滤波器的潜力.     

Engineering ZnO nanowire surfaces via a chemical method

Quasi‐aligned porous ZnO nanowire arrays are promising architectures for potential applications in catalysts, gas sensors and solar cells. However, processes for conversion of ZnO nanowire arrays into porous ones have rarely been reported. Here, we report a facile chemical method for the synthesis of ZnO nanowire array with porous surface. The morphology and structure of the obtained products have been investigated with field‐emission scanning electron microscopy and high‐resolution transmission electron microscopy. Time‐dependent experiments have also been carried out to better understand the formation process of porous structures on the nanowire surfaces. The obtained porous ZnO nanowire arrays may find potential applications in catalysts, solar cells and gas sensors due to the large surface area of the yielded products.     

Synthesis,Crystal Structure and Spectroscopy of <Emphasis Type="Italic">catena-</Emphasis>poly-bis(azido-<Emphasis Type="Italic">N1,N1</Emphasis>)(2-Aminopyrimidine)Copper(II)

Abstract The compound [Cu(ampym)(μ_1,1-N₃)₂]_n (ampym = 2-aminopyrimidine) has been synthesized and characterized by X-ray crystallography and infrared spectroscopy. In addition, Ligand Field and powder EPR measurements have been performed. The structure is solved in space group P21/c with a = 7.303(2), b = 19.716(4), c = 5.949(1) ?, β = 98.17(3), V = 847.9(3) ?³, Z = 2 with final R = 0.0382. The coordination geometry around the Cu(II) ion is distorted square pyramidal, with four nitrogen atoms of four bridging azido anions in the basal plane with Cu–N distances that range from 1.998(3) to 2.069(3) ?. The apical position is occupied by a nitrogen atom of the ampym molecule at a Cu–N distance of 2.169(3) ?. The trans-basal angles are 165.7(1) and 143.9(1)°. Weak hydrogen bonding is observed between the two amine hydrogen atoms and nitrogen of an azide anion and the pyrimidine-ring nitrogen atom of a neighbouring molecule (N···N distances 3.174(5), 3.106(4) ?). These last hydrogen bonds (N7···N3) are forming so-called “Watson-Crick type” hydrogen bonds. In the infrared the vibrations of the coordinated azide anion are observed at 2,062, 1,273 and 655 cm⁻¹, while the Cu–N vibrations are observed at 370 and 224 cm⁻¹. Ligand-field and EPR spectra are uneventful and give spectral parameters expected in the range for such Cu(II) compounds. Magnetic susceptibility measurements reveal a weak antiferromagnetic interaction between the Cu(II) ions. Index Abstract A new Cu(II) compound, [Cu(2-aminopyrimidine)(μ_1,1-N₃)₂]_n has been synthesized and characterized by X-ray crystallography and by IR, Ligand Field, EPR spectroscopy and magnetic susceptibility. The coordination geometry around the Cu(II) ion is distorted square pyramidal, with four nitrogen atoms of four bridging azido ligands in the basal plane with Cu–N distances that range from 1.998(3) to 2.069(3) ?. The apical position is occupied by a nitrogen atom of the ampym molecule at a Cu–N distance of 2.169(3) ?. Also a very interesting hydrogen bond system occurs between pairs of ligands in the lattice. .     

Fluorogermanate glass with reduced content of OH-groups for infrared fiber optics

The hydroxyl (OH⁻) impurities in germanium oxide (GeO₂)-based glasses cause a strong absorption band between 2.4 and 3.6 μm, which makes this region of the electromagnetic spectrum inaccessible for signal transmission. To eliminate the OH⁻ absorption, PbF₂ was employed by partially replacing the PbO content in the following compositions: 56GeO₂−(31-x) PbO–9Na₂O–4Ga₂O₃–xPbF₂ (x = 0, 3, 6, 9, 15, 25, 31). The removal of OH^- ions in relation to the concentration of PbF₂ incorporated in the glass-forming liquid was systematically studied. Differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy were respectively used for the analysis of glass devitrification and optical properties. The results of FTIR suggest that over 99% OH⁻ impurity was removed, as compared to glasses without a purification process. An optimized core/cladding glass pair was then selected and the rod-in-tube technique was used. Fiber drawing conditions were established using the measured viscosity data and the devitrification range. The low OH⁻ absorption fiber has demonstrated the transmission window up to 4 μm with a loss of 2.34 dB/m at 1.49 μm.     

X-ray Powder Diffraction Study and Vibrational Spectra of Calcium Cadmium Formate

It has been established that the double salt CaCd(HCOO)₄ is isostructural with CuSr(HCOO)₄. It crystallizes in the monoclinic space group P2/c - C2h⁴ with lattice parameters: a = 7.5309(2)Å, b = 8.8815(4)Å, c = 6.4267(2)Å, β = 92.153(2), and V = 429.55(3)ų. The analysis of the infrared spectra shows that the internal formate modes reflect the existence of two crystallographically inequivalent formate groups in the crystal lattices. The additional split of each formate mode into two components is due to the correlation field splitting. The frequency separations between the asymmetric and symmetric C-O stretching modes are explained in terms of different C-O bond lengths within each formate group and the frequency separation of the v₄ components in terms of different C-O bond lengths of the formate groups.     

Optical Properties of some TMTS(T)F2X Compounds

The infrared and visible reflectance of TMTSF₂PF₆ is reported. Data are given at high and low temperatures in the metallic range and for polarizations along and perpendicular to the highly conducting direction. Among the interesting features are a pseudogap in the far infrared conductivity along the highly conducting direction, and a mid-infrared plasma edge in the perpendicular direction. Unusual temperature dependent, near infrared absorptions may have implications for the band structure. For comparison some data on TMTSF₂AsF₆, TMTSF₂ClO₄, TMTSF₂ReO₄ and TMTTF₂PF₆ are presented.     

弛豫铁电单晶的多功能特性及其器件应用

以Pb(Mg1/3 Nb2/3)O3-PbTiO3(PMN-PT或PMNT)为代表的弛豫铁电单晶具有远高于常用锆钛酸铅Pb(Zrx Ti1-x)O3(PZT)陶瓷的压电性能,引起了基于新一代压电单晶的功能器件研究热潮.本研究团队在国际上率先利用Bridgman方法生长出了大尺寸、高质量PMN-PT等弛豫铁电单晶(d33...     

High‐Stability Control of Multizone Furnaces using Optical Fibre Thermometers

A high‐stability temperature control system for a 1500 °C multizone furnace has been developed and experimentally verified. It relies on the utilisation of optical fibre thermometers as precise temperature sensors. The strong thermal coupling between the zones requires an exact quantitative determination of the thermal exchange process. A holistic approach integrating theoretical and practical considerations has lead to a short‐term stability of less than 0.02 K at a temperature level of 1500 °C which is about one order of magnitude better than a temperature control based on thermocouples.     

Refractive index and material dispersions of multi-component oxide glasses

Refractive index dispersion curves in the wavelength region of 0.40 to 5.03 μm are presented for multi-component oxide glass systems: borate, silicate, aluminate, germanate, tellurite, antimonate and heavy metal gallate. The material dispersion was determined using the refractive index data. Reflection spectra in the ultraviolet and infrared regions were measured to investigate the effects of electronic transitions and lattice vibrations on the material dispersion. Thallium tellurite, thallium antimonate and lead gallate glasses exhibit zero material dispersion wavelengths (ZMDWs) over 2.4 μm. The factors affecting the ZMDW are discussed.     

高质量CVD金刚石膜的氧化损伤

高质量CVD金刚石膜的高温损伤的研究是其高温应用的基础。抛光的金刚石膜经780℃保温3min后,红外透过和可见光的透过率开始下降;780℃保温15min后,其红外透过和可见光的透过率严重受损。扫描电镜、原子力学显微镜及台阶仪的结果表明：CVD金刚石膜氧化的开始阶段主要集中在晶界、表面孔洞等缺陷处,随后导致金刚石膜的晶面也开始刻蚀,表面粗糙度增大,最终使得金刚石膜丧失红外和可见光的透过。     

利用表面等离子激元提高红外探测器效率的研究

目前关于提高红外热探测器吸收效率的研究,主要是上表面金属光栅结构的研究,该结构存在入射光被表面金属反射的问题。本研究提出了一种内部等离子体谐振吸收的红外探测器结构。分析了光栅及探测器结构参数对红外光学吸收的影响,采用COMSOL软件仿真,研究了介质-金属-介质-金属结构红外探测器的吸收效率,并通过结构参数的优化使吸收结构对特定红外波长的吸收率达到99.9;以上,在整个波长范围内平均吸收效率达37.4;。     

Growth of heavily C-doped GaAs/AlGaAs MQW structures by MOVPE for 2–3 μm normal incidence photodetectors

The growth and intersubband optical properties of high quality heavily doped p-type GaAs/AlGaAs multiple quantum well (MQW) structures are reported. The MQWs were fabricated by the atmospheric pressure metalorganic vapor phase epitaxy process using liquid CCl₄ to dope the wells with C acceptors (N_a ≈ 2 × 10¹⁹ cm⁻³). A constant growth temperature was maintained for the entire structure while different V/III ratios were used for the well and barrier regions. By this process it is possible to achieve both high C doping densities in the wells and to simultaneously obtain good quality AlGaAs barriers. Fourier transform infrared spectroscopy measurements on heavily doped 10-period MQW structures reveal a new absorption peak at 2 μm with an effective normal incidence absorption coefficient of 4000 cm⁻¹. Photocurrent measurements on mesa-shaped diodes show a corresponding peak at 2.1 μm. The photodiodes exhibit a symmetrical current-voltage characteristic and a low dark current, which are indicative of a high quality MQW structure and a well-controlled C doping profile. The 2 μm absorption represents the shortest wavelength ever reported for any GaAs/AlGaAs or InGaAs/AlGaAs MQW structure and should be very useful for implementing multicolor infrared photodetectors.     

Crystal Structure of [Co(NH3)5NO3](NO3)(PF6)?·?1.5H2O and the Vibrational Bands of its Normal and 15NO3-Enriched Cation

The crystal structure of [Co(NH₃)₅NO₃](NO₃)(PF₆) ·1.5 H₂O was studied by X-ray diffraction methods in order to obtain the unknown molecular structure of the [Co(NH₃)₅NO₃]²⁺ cation . The substance crystallizes in the monoclinic system, space group C2/m, with a = 18.6231(6) ?, b = 7.8757(3) ?, c = 9.6434(3) ? and β = 95.484(2)°. An infrared and Raman study of the bromide salt was also performed and the spectra interpreted with the aid of ¹⁴NO₃/¹⁵NO₃ isotopic replacement and quantum chemistry calculations. E.L. Varetti — Member of the Carrera del Investigador Científico, CONICET, R. Argentina