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1.
In this paper, Zn-doped VO2 nanoparticles have been successfully fabricated by a two-step hydrothermal-annealing process, and the thermally induced visible light transmittance enhancement of Zn-doped VO2 has been studied for the first time. It is found that Zn-doped VO2 not only exhibits excellent solar modulation ability (ΔTsol = 15.27%) but also can reduce the phase transition temperature and increase the visible light transmittance after the heat-induced phase transition (ΔTlum=+5.78%). Moreover, with the increase of Zn doping concentration, the phase transition temperature (Tc) and phase transition hysteresis (ΔT) both decrease. It is shown that the Zn-doped VO2-PU films not only have good solar light modulation ability and properties of improving visible light transmission after phase transition, but also have good durability. The research result is of great significance for improving the visible light transmittance after phase transition and realizing the practical application of VO2 in the field of smart windows.  相似文献   
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The palladium-catalysed amination of readily accessible bromofluorans and bromobenzo[a]fluorans has been accomplished with a series of anilines and morpholine. The resulting aminofluorans generated intense black shades upon formulation in methyl stearate containing bisphenol A. The route provides an alternative approach to various amino substituted fluorans without the need of a series of individual diphenylamine intermediates.  相似文献   
4.
Vanadium dioxide films were prepared by DC and rf reactive magnetron sputtering of a 99.7% pure vanadium target in an Ar+O2 plasma with a well-controlled oxygen partial pressure. The films were deposited onto normal glass substrates at 400°C. The films showed a metal–semiconductor transition at the temperature, τc=65–68°C. Optical and electrical properties of the films were investigated around the metal–semiconductor phase transition and found to be very sensitive to the oxygen flow rate. Sheet resistance of the films were recorded using a two-point probe over the temperature range 26τ100°C. It was observed that the sheet resistance can change by three orders of magnitude when heating the films from room temperature to temperatures above the transition. Transmittance of the films was obtained in the 300λ2500 nm wavelength range at two extreme temperatures (i.e. 26°C and 100°C). The luminous transmittance for the films was rather unaffected with heating, whereas near-infrared transmittance showed lower values. Optical constants, n and k were measured using ellipsometry. The semiconducting state optical constants were found to be 2.67 and 0.04 for n and k, respectively, while the metallic state values were 2.26 for refractive index and 0.3 for the extinction coefficient. The samples showed a slow deterioration when left in the laboratory for a period of one year.  相似文献   
5.
Vanadium dioxide (VO2) films have been proposed as energy efficient window coatings for their thermochromism, with which the solar energy transmission in the IR region may be controlled passively. These coatings suffer from low visible (or luminous) transmission (380–760 nm in wavelength), which hinders their practical uses. We here consider an antireflection (AR) coating for the VO2-based window. Optical calculation was first performed upon a basic structure for thermochromic window composed of a VO2 layer on glass with an AR layer of refractive index n and thickness d. Optimization was carried out on n and d for a maximum integrated luminous transmittance (Tlum). The calculation demonstrates that the optimal n value changes with thickness of VO2, and at n≈2.2 it gives the highest Tlum enhancement from 32% (without AR coating) to 55% for 50-nm VO2. Experiment was done on a structure of 50-nm VO2 on quartz glass using ZrO2, of which n≈2.2 matching the best n value, as AR coating. Formation of an optimized structure, ZrO2 (56 nm)/VO2 (50 nm)/quartz, was done by sputtering, and its optical properties were characterized with spectrophotometry. An improvement of Tlum from 32.3% to 50.5% was confirmed for the semiconductor phase with similarity also for the metallic one. The IR switching properties were not much deteriorated.  相似文献   
6.
Polyalkylthiophene thin films have been prepared to enable the characterisation of the films with transmission spectroscopy and profilometry for the first time. The optical properties of the films as a function of annealing temperature are discussed. The changes in absorption with time are related to thermochromism.  相似文献   
7.
以2,4-二硝基苯肼与取代苯甲醛为原料,通过室温固相反应合成了6种席夫碱衍生物,用元素分析、核磁共振等方法对产物进行了表征,并利用DSC技术对其变色过程进行了研究。用密度泛函理论的B3LYP方法对产物的分子结构进行优化,从理论上探讨了他们的变色机理。研究表明,此类席夫碱衍生物作为热致变色材料具有变色敏锐、颜色对比明显、可逆性好以及变色温度高等特点,是一类具有良好应用前景的可逆热致变色材料。  相似文献   
8.
制备了溴甲酚紫-Co(Ⅱ)-十八醇复配物,改变原料用量,得到一系列不同配比的复配物。运用变温IR光谱初步探讨了复配物热变色机理。讨论了熔剂化合物对热变色复配物熔点,变色温度,变色敏锐度等方面的影响。  相似文献   
9.
Hybrid atmospheric pressure chemical vapour and aerosol assisted deposition via the reaction of vanadium acetylacetonate and a suspension of preformed titanium dioxide or cerium dioxide nanoparticles, led to the production of vanadium dioxide nanocomposite thin films on glass substrates. The preformed nanoparticle oxides used for the aerosol were synthesised using a continuous hydrothermal flow synthesis route involving the rapid reaction of a metal salt solution with a flow of supercritical water in a flow reactor. Multifunctional nanocomposite thin films from the hybrid deposition process were characterised using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The functional properties of the films were evaluated using variable temperature optical measurements to assess thermochromic behaviour and methylene blue photodecolourisation experiments to assess photocatalytic activity. The tests show that the films are multifunctional in that they are thermochromic (having a large change in infra-red reflectivity upon exceeding the thermochromic transition temperature) and have significant photocatalytic activity under irradiation with 254 nm light.  相似文献   
10.
Thermochromic VO2-based films have higher infrared transmittance below a “critical” temperature τc than above this temperature and can be used for regulating the solar energy transmittance Tsol in energy efficient windows. Pure VO2 is not practical, though, since (i) the modulation of Tsol is too small at τc, (ii) the luminous transmittance is too low, and (iii) τc is too high. This paper discusses how these three challenges can be met. Specifically, using VO2-based nanoparticle composites rather than films makes it possible to significantly alleviate (i) and (ii), Mg doping of VO2 can give further improvements of (ii), and W doping (and to some extent also Mg doping) is important for (iii) and can bring τc to a comfort temperature. The paper hence delineates a path towards practically useful thermochromic fenestration.  相似文献   
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