ITO导电膜红外发射率理论研究

根据红外辐射理论和薄膜光学原理计算了高品质ITO(indium tin oxide)导电膜的红外发射 率,其理论曲线与实测曲线基本符合. 并得出方块电阻小于30Ω时,ITO膜在红外波段8—14μ m的平均红外发射率理论值小于0.1.实际制备方块电阻小于10Ω的ITO膜具有优良的红外隐身 性能. 讨论了高品质ITO膜具有低红外发射率的物理机理,并提出了低红外发射率临界方块电 阻值,这有利於理论研究和工艺制备红外隐身ITO膜. 关键词： 红外发射率 ITO薄膜 理论计算 方块电阻     

Preparation, characterization and infrared emissivity study of helical polyurethane@SiO2 core-shell composite

Helical polyurethane@SiO₂ (HPU@SiO₂) core-shell composite was prepared after surface modification of SiO₂ nanoparticles. HPU@SiO₂ was characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet (UV) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicate that the helical polyurethane has been successfully grafted onto the surfaces of the modified SiO₂. HPU@SiO₂ composite exhibits clearly core-shell structure. The ultraviolet absorption and crystallizability of HPU@SiO₂ are changed due to the shell of helical polyurethane, which possesses regular single-handed conformation and inter-chain hydrogen bonds. The infrared emissivity of HPU@SiO₂ was also investigated. The result indicates that the interfacial interactions between organic shell and inorganic core induce the infrared emissivity value being reduced from 0.781 for SiO₂ to 0.503 for HPU@SiO₂.     

Preparation of a novel infrared low-emissive coating from the Cu powder modified by the polyethylene wax

Cu powder was coated with polyethylene wax via the flux-capping method in hope to avoid the oxidation of it, so the increment of the infrared emissivity of the coating can be greatly reduced. The prepared product was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The infrared emissivity of the prepared material was measured by Infrared Emissometer. The influence parameters that will affect the emissivity of the coating were systematically investigated, such as the content of coated Cu powder, coating fineness, coating thickness and aging process. The results indicated that the infrared emissivity value of the coating was reduced after Cu powder was coated with polyethylene wax. The polyethylene wax/Cu composites presented a homogenous sheet structure when the content of Cu powder increased to 30 wt.%, and it has a lower emissivity. The infrared emissivity of the coating increases rapidly as thickness increases and becomes steady above thickness of 70 μm. The composite coating exhibits lower emissivity value and excellent physical properties at coated Cu content of 20 wt.%. The emissivity of the coating that was prepared from the modification of the Cu powder was decreased with the decrement of the grinding fineness and increased with the aging time. The emissivity of the coating that was prepared from the modification of the Cu powder is always lower than that of the coating that only composed of the Cu powder with the increment of the aging time. Therefore, it can be concluded that the anti-oxidation of Cu powder is greatly improved after it was modified by polyethylene wax, which results in a novel coating with long-run low emissivity.     

Synthesis and fluorescence study of sodium-2-(4′-dimethyl-aminocinnamicacyl)-3,3-(1′,3′-alkylenedithio) acrylate

We synthesized two new compounds: Sodium 2-(4′-dimethyl-aminocinnamicacyl)-3,3-(1′,3′- ethyl- enedithio) acrylate (STAA-1) and Sodium 2-(4′-dimethyl-aminocinnamicacyl)-3, 3-(1′,3′-propylenedithio) acrylate (STAA-2). The maximum absorption of these compounds ranges from 460 to 520 nm with different molecular structures in different solvents. Meanwhile, the emission peak of these compounds arranges from yellow (510 nm) to red (605 nm). The emission spectra show red shift according to the strength of the hydrogen bonding property of the solvent. But the absorption spectra do not show clearly relationship with the strength of the hydrogen bonding property of the solvent. The Stoke shift of the compounds ranges from 42 to 102 nm. It changes in the following order, EtOH>H₂O>DMF, and STAA-1>STAA-2 in the same solvent. The fluorescent quantum yield of STAA-1 was measured to be 7.12% with quinine sulphate as the standard compound in ethanol. Furthermore, the relationship of the fluorescence of STAA-1 with pH (ranges form 4 to 14) in water (c=∼10⁻⁴) was studied to make sure that these compounds could be used as proton sensors.     

Spectroscopic study on the 4′-(4-pyridyl)-2,2′:6′,2′′-terpyridine and its metal complexes

Multitopic ligand, 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine (pyterpy), has attracted growing attention because of its unique structural features, optical and electrochemical properties. Here, we report spectroscopic studies of pyterpy and its metal complexes in methanol solution. For the pure pyterpy, the ligand emission intensity increased with its concentration in the dilute solution, but decreased when its concentration was over 1.3×10⁻⁵ mol/l due to the concentration quenching. No significant influence on the ligand luminescence was observed for the Zn²⁺-pyterpy complex but strong luminescence quenching was observed for the electroactive Fe²⁺- and Co²⁺-pyterpy complexes. The lanthanide (Sm³⁺, Eu³⁺ and Tb³⁺) complexes of the pyterpy showed both ligand and lanthanide ion emissions, especially for the Tb³⁺-pyterpy complex, suggesting that the excited energy of pyterpy ligand could be efficiently transferred to the central Tb³⁺ ions. The luminescence was pH sensitive with the strongest emission in the neutral solution. The results indicated that the multitopic ligand of pyterpy could not only act as linkers for the metal-directed building blocks, but also act as optical materials with its own emission at about 364 nm and as light antenna for the lanthanide ions.     

Infrared radiant emissivities of ceramics with spinel structure

The infrared radiant ceramic materials were prepared by calcination at high temperature. Based on the study of infrared radiant emissivity and X — ray diffraction spectra, the results indicate that spinel structure possesses the higher infrared radiant emissivity. The reason of the higher infrared emissivity of the spinel structure has been explained according to the Group Theory.     

Low infrared emissivity of polyurethane/Cu composite coatings

Polyurethane/Cu composite coatings with low infrared emissivity near to 0.10 at the wavelength of 8-14 μm were prepared by a simple and convenient process. The influences of the content of Cu powder, surface roughness, coating thickness and temperature on infrared emissivity of the coatings were systematically investigated. The results indicated that the emissivity decreases significantly with increasing content of Cu powder and coating thickness. The coatings with smooth surface exhibit lower emissivity values than those with rough coatings. Moreover, we found the relationship between the emissivity of coatings and temperature presents a “U” type, and the emissivity reaches to the minimum at about 380 K. The mechanisms of low emissivity were proposed by optical theories, which are found to be in a good agreement with the experimental results.     

Role of surface defects and microstructure in infrared optical properties of thermochromic VO2 materials

Thermochromic vanadium dioxide VO₂ exhibits a semi-conducting to metallic phase transition at T_c=68 °C, involving strong variations in optical transmittance, reflectance and emissivity. However, the optical contrasts observed in thin films or nanostructured compacted samples seem to depend on both surface microstructure and surface crystal texture. In the case of opaque materials, surface defects might play a drastic role in optical reflectivity. As the high temperature metallic phase of VO₂ is opaque for infrared radiations, we used aluminum samples as standards allowing us to correlate reflectivity responses with porosity and surface defects. Then, various polycrystalline and nanostructured VO₂ samples compacted at various pressures and presenting variable surface roughness were prepared. Thin films were deposited by radio frequency sputtering process. The samples were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Optical properties (reflectance and emissivity) were analyzed above and below the transition temperature, making use of specific FTIR equipments. In thin films, the deposited VO₂ phase was systematically oriented and surface porosity was very weak. In polycrystalline samples, as the compaction pressure increased, surface porosity decreased, and infrared optical contrast increased. In such samples, preferred orientations were favored for low applied pressures. These features clearly show that the main parameters conditioning the optical contrast should be the surface defects and porosity, not the preferred crystal orientations. As an additional interesting result, the surfaces formed from compacted nanocrystalline VO₂ powders present improved optical contrast for reflectance and emissivity properties.     

颜料含量对复合涂层红外发射率的作用机制研究

以聚氨酯(PU)为粘合剂,某片状金属粉为颜料,采用刮涂法制备了PU/片状金属复合涂层。对不同颜料含量条件下涂层的红外发射率进行了测试,并采用扫描电镜对涂层的微结构进行了观察。发射率测试结果表明,涂层发射率随金属粉含量增加呈“∪”型变化。微结构观察结果表明,PU/片状金属复合涂层由PU和片状金属粉交错堆叠而成,具有类似一维光子结构特征。基于涂层的微结构特征,对具有转折变化特征的4个金属粉含量点状态下涂层中一维光子结构的反射光谱进行了模拟计算,结果表明：PU/片状金属复合涂层的发射率随金属粉含量变化呈“∪”型变化关系特征主要是由涂层中一维光子结构的主反射峰中心波长随颜料含量增加所产生的蓝移现象引起的。     

Electrochromic properties of WO3 as a single layer and in a full device: From the visible to the infrared

Most of the applications of electrochromic devices (ECDs) concern the visible whereas there is a significant need for ECDs active in the infrared (IR) region. After optimization, WO₃ thin films show significant variation in emissivity, as high as 78% and 49% in the MW (3-5 μm) band and LW (8-12 μm) band, respectively. The incorporation of the EC WO₃ layer in ECDs is discussed in terms (i) of device configuration (i.e. position of the active layer on top or bottom of the device), (ii) of the choice of materials including the transparent conductive layer, electrolyte, counter electrode, and (iii) of the thickness of each layer. Initial trends in optical modulation of the ECDs are deduced from simulation of the optical indexes (n and k). Experimental data based on half-cell assembly confirm the modulation in emissivity in the IR region for WO₃/Ta₂O₅/NiO-based devices with however lower values than the predicted ones.     

Synthesis, crystal structure, EPR and electrochemical studies of copper(II) dipicolinate complex with 2,2′-dipyridylamine ligand

The (2,2′-dipyridylamine)(pyridine-2,6-dicarboxylato)copper(II) trihydrate complex was synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. The copper(II) center is surrounded by one bidentate 2,2′-dipyridylamine (dpa) and one tridentate dipicolinate (dpc) ligand, and exhibits a distorted square-pyramidal geometry. The crystal packing involves both hydrogen-bonding and π-π interactions. The solvent water molecules link monomers to one another through hydrogen-bonding interactions, forming ladder-type chains in the ab plane. π-π interactions also occur between the dpa rings of neighboring molecules and are responsible for interchain packing. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110 K), indicate the presence of the unpaired electron in the d_x²-y² orbital. The evaluated metal-ligand bonding parameters showed strong in-plane σ- and π-bonding. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centered electroactivity in the potential range ±1.25 V versus Ag/AgCl reference electrode.     

Chemiluminescence of 3,3′,4,4′-tetrahydro-1,1′-biisoquinolinium salts

Basic methanolic solutions of 2,2′-dimethyl-3,3′,4,4′-tetrahydro-1,1′-biisoquinolinium iodide (1) chemiluminesce brightly when exposed to oxygen. The first reaction is between base and dication to form a mixture of olefins. These electron-rich olefins are formed by proton removal from, or RO- addition to, the dication and subsequent redox equilibria. The olefins react with ground state O₂ by another redox reaction involving ROH as catalyst. Several oxygenated products are formed and several emission peaks appear. One correlation between a product and an emission peak is possible.     

Infrared emissivities of Mn,Co co-doped ZnO powders

<正>Infrared emissivities of Zn_0.99-xMn_0.01Co_xO（x=0.00,0.01,0.03,0.05） powders synthesized at different calcination temperatures by solid-state reaction are investigated.Their phases,morphologies,UV absorption spectra,and infrared emissivities are studied by XRD,SEM,UV spectrophotometer,and an IR-2 dual-band infrared emissometer in a range of 8μm-14μm.Doped ZnO still has a wurtzite structure,and no peaks of other phases originating from impurities are detected.The optical band-gap decreases as the Co content and calcination temperature ascend,and of which the smallest optical band gap is 2.19 eV.The lowest infrared emissivity,0.754,is observed in Zn_0.98Mn_0.01Co_0.01O with the increase in Co concentration.The infrared emissivity experiences fluctuations as the calcination temperature increases,and its minimum value is 0.762 at 1100℃.     

Synthesis, characterization and infrared emissivity study of polyurethane/TiO2 nanocomposites

In this study, polyurethane/titania (PU/TiO₂) nanocomposites were prepared in ultrasonic process and characterized by fourier transform IR spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared emissivity analysis. The TEM and SEM results indicated that the nanoparticles were dispersed homogeneously in PU matrix on nanoscale. TGA-DSC confirmed that the heat stability of the composite was improved. Infrared emissivity study showed that the nanocomposite possessed lower emissivity value than those values of pure polymer and nanoparticles.     

Dependence of infrared radiation on microstructure of polymer derived ceramic coating on steel

High infrared emissivity ceramic coatings were prepared on 304 steel by pyrolyzing reactions with poly(hydridomethylsiloxane) (PHMS) and Al/Cr₂O₃ based mixing powders. The effects of pyrolysis temperature, testing temperature and surface roughness on infrared radiation of polymer derived ceramic coating were systematically investigated. The results indicated that the coating pyrolyzed at 800 °C exhibited a slightly higher infrared emissivity value than that of the coating pyrolyzed at 600 °C, which was attributed to the enhancing photon emission caused by the complete conversion of Al to Al₂O₃ and PHMS pyrolysis into SiO₂, together with the introduction of Cr₂O₃ based mixing powders. The emissivity value in 3–8 μm waveband of the coating was lower about 0.03 at 600 °C compared with 800 °C testing temperature, while the emissivity value was almost the same in 8–20 μm waveband. The high surface roughness of the coating led to a slightly increasing emissivity due to the enhancing infrared absorbance.     

Characteristic dielectric parameters of para-, ferro- and antiferro-electric phases of (S)-4-(1-methylheptyloxycarbonyl)phenyl-4′-(6-pentanoyloxyhex-1-oxy)biphenyl-4-carboxylate

Frequency and temperature dependence of dielectric parameters of a liquid crystalline compound (S)-4-(1-methylheptyloxycarbonyl)phenyl-4′-(6-pentanoyloxyhex-1-oxy)biphenyl-4-carboxylate under planar orientation of the molecules have been investigated in the frequency range 1 Hz-10 MHz. This compound possesses smectic paraelectric (SmA*), ferroelectric (SmC*) and antiferroelectric (SmC_A*) phases. Dielectric spectroscopy suggests the existence of a relaxation mechanism in the SmA* phase, which behaves as a soft mode. In the SmC* phase two relaxation modes are observed. One mode continues from the SmA* phase with decreasing dielectric strength and the other has characteristics of the Goldstone mode. Two dielectric relaxation modes have been observed for the SmC_A* phase. These two modes are related to the antiferroelectric ordering and the helical structure of the SmC_A* phase.     

Nickel ion—A structural probe in BaO-Al2O3-P2O5 glass system by means of dielectric, spectroscopic and magnetic studies

BaO-Al₂O₃-P₂O₅ glasses containing different concentrations of NiO (ranging from 0 to 1.0 mol%) were prepared. A number of studies viz., chemical durability, differential thermal analysis, spectroscopic (infrared, optical absorption spectra), magnetic susceptibility and dielectric properties (constant ε′, loss tan δ, AC conductivity σ_AC over a range of frequency and temperature) of these glasses have been carried out. The studies on chemical durability indicate that there is a significant increase in the corrosion resistance of the glasses; where as the results of differential thermal analysis suggests that there is a substantial improvement in the glass forming ability, with increase in the concentration of NiO up to 0.6 mol% in the glass matrix. The optical absorption, magnetic susceptibility and IR spectral studies point out nickel ions occupy both tetrahedral and octahedral positions in the glass network; the later positions seems to be dominant when the concentration of NiO is beyond 0.6 mol% in the glass matrix. The studies of dielectric properties reveal that the presence of nickel oxide in the glass network causes a considerable improvement in the insulating strength of the se glasses when the concentration of NiO?0.6 mol%.     

Preparation and photoluminescent properties of europium complexes with methoxy derivatives of 2′-hydroxy-2-phenylacetophenones

The complexes Eu(L₁)₃·2H₂O (I) [where L₁=2′-hydroxy-4′-methoxy-2-phenylacetophenone], Eu(L₂)₃·2H₂O (II) [where L₂=2′-hydroxy-4′-methoxy-2-(p-methoxyphenyl) acetophenone], Eu(L₃)₃·2H₂O (III) [where L₃=2′-hydroxy-4′, 6′-dimethoxy-2-phenylacetophenone] and Eu(L₄)₃·2H₂O (IV) [where L₄=2′-hydroxy-4′, 6′-dimethoxy -2-(p-methoxyphenyl) acetophenone] were synthesized. Energy dispersive X-ray analysis (EDX) results showed the presence of europium in all the complexes. These complexes were further characterized by infra-red spectroscopy, thermal analysis, scanning electron microscopy (scanning electron microscope) and elemental analysis. The synthesized complexes emit red luminescent with main peak at 612 nm on exposure to UV light at 354 nm. The complexes emitting bright red color might be applicable for optical devices and solid-state lamps for general illumination purposes.     

各向异性粗糙海面的红外反射特性研究

海面背景的干扰影响着红外系统的探测、识别性能,海面的红外辐射研究对于红外系统的设计、使用和评估具有十分重要的意义.基于Cox-Munk模型对海面的红外反射率进行了分析计算,全面考虑风速、风向、遮挡效应、入射方向、观测方向等各种影响,建立海面红外反射模型,推导出各向异性粗糙海面的红外反射率计算方法,并计算出海面的红外反射...     

中国遥感卫星辐射校正场陆表热红外发射率光谱野外测量

中国遥感卫星辐射校正场陆表发射率光谱是利用陆表场地进行遥感器红外通道绝对辐射定标的关键因子之一。基于光谱平滑的温度与发射率分离反演迭代算法,利用高精度的BOMEM MR154傅里叶变换红外光谱仪和红外标准板,对敦煌戈壁陆表发射率光谱进行测量。获得了不同时间和地点测量的陆表发射率光谱数据,并与利用CE312通道式红外辐射计在相同区域的测量结果进行比较分析。结果表明各个通道发射率的差别均在0.012以内,具有较好的一致性。利用该发射率光谱测量结果,可以在敦煌戈壁——中国遥感卫星辐射校正陆面场,对目前国内外主流的遥感卫星热红外通道进行在轨场地绝对辐射定标。