Mesoporous SiO 2 /VO 2 double-layer thermochromic coating with improved visible transmittance for smart window
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Visible spectrum
Slab
Absorbance
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적외선 투과 특성을 이용하여 광학 창 등으로 사용되는 세라믹 재료들은 광학적 특성이 잘 공개되어 있지 않다. 통상적으로 사용되는 굴절률 시험기를 이용하여 고온 세라믹 재료의 굴절률을 측정하는 것은 매우 어렵기 때문에 특별한 방안이 도입되어야 한다. 본 연구에서는 간접적인 방법을 통해 고온 조건에서 세라믹 재료의 광학특성을 평가하는 실용적인 방법을 제시하고자 한다. 먼저 평가대상인 세라믹 재료 샘플을 요구되는 고온 조건을 유지하기 위한 시스템을 제작하여 광분광기에 장착하였다. 이 시스템을 이용하여 온도를 변화하며 시료 온도에 따른 투과율을 측정하였다. 이렇게 측정된 투과율 데이터는 Sellmeier 분산식을 적용하는 광학 시뮬레이션 모델에 적용되어 굴절률 자료를 산출하는데 사용된다. 이 시뮬레이션 모델은 시행착오법을 이용하여 Sellmeier 분산식에 포함되는 변수들을 찾는데 이용된다. 이를 이용하여 굴절률을 계산하며 그 값을 이용하여 다시 투과율을 계산하고 그 결과를 측정된 투과율과 비교하여 그 결과가 일치할 때까지 반복하여 그 온도에서 재료의 변수로 정하였다. 이 방법을 사파이어 재료에 적용하여 그 결과를 상온에서 공개 데이터와의 비교를 통해 검증하였다. A method for estimating the optical characteristics of ceramic materials under high temperature conditions has been applied and evaluated. For that purpose, an interface system combined with a photo-spectrometer was made to keep the samples at the required high temperature. The transmittance of the samples was measured at various temperatures. The measured transmittance data was used to estimate the refractive index using an optical simulation model in conjunction with the Sellmeier equation. The Sellmeier equation parameters were selected by trial-and-error when the transmittance recalculated using the estimated refractive index was compared with the measured transmittance. Furthermore, the estimated refractive indices were checked by a comparison with the reference data at some typical wavelengths at room temperature.
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The catalysts of strongly acidic mesopore include the strongly acidic components on the pore wall of mesoporous materials,the surface of the mesopores reformed by sulfonic acid groups,the heat treatment of microporous zeolites and the wall of mesoporous materials containing the zeolite structure of strong acidity.The strongly acidic mesoporous catalysts of various types possess different synthetic methods and characteristics.The synthesis of strongly acidic mesoporous catalysts is systemically introduced in this paper and the research prospects of strongly acidic mesoporous catalysts are forecasted.
Mesoporous organosilica
Sulfonic acid
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The transmittances of coated paper and base paper were measured in a narrow wavelength range over which the absorption of the coating was high and the base paper's absorption was low. The effect on the accuracy of the large spatial variations of the reflectance of the paper was eliminated by the application of a highly reflective, partially transparent plate. The plate was placed between the radiation source and the paper. Because of the high reflectance of the plate, most of the radiation that was transmitted by the plate was pumped through the paper. Based on a model of diffuse transmittance of weakly absorbing coated media, it was shown that there was a nearly linear correlation between coating weight and relative transmittance. After experimental confirmation, the results were used to develop an apparatus for the measurement of coating weights during the paper coating process. Two measuring units were installed along the paper pass for measuring the transmittance of the base paper and of the coated paper, respectively. The units were interfaced with a computer that was programmed to calculate the coat weight and display the result on monitors.
Base (topology)
Diffuse reflection
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Mesoporous organosilica
Thermal Stability
Template method pattern
Hydrothermal Synthesis
Specific surface area
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Characterization
Mesoporous organosilica
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the refractive index) transmittance spectrum to the measured transmittance spectrum. There are two other techniques which are discussed in this report: A quick, approximate method vs. the exact derivation. What the authors have not been able to find in the literature is the exact transmittance dependence as a function of the refractive indices (layers) through which the light passes and which accounts for the substrate back reflections. There are undocumented approximation methods as well as one in the literature by Cheremukhin and Rozhnox. Otherwise, most texts either derive the transmittances through optical multilayers or just the effect of back reflections on the transmittance for thick substrates. Without correcting for substrate back reflections, the derived refractive indices from the measured transmittances are in error by as much as 10%. In this work, the authors have utilized both an exact and an approximate method of determining the refractive index of the film. It is found that both the exact and approximate methods of determining the refractive index of thin optical coatings are within the measurement errors of commercially available spectrophotometers.
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The recent progress, particularly in this decade, in catalytic applications of mesoporous ZSM-5 was reviewed. Mesoporous ZSM-5 materials aim to combine the shape-selectivity from micropores of ZSM-5 with enhanced mass transportation from the additional mesoporosity in catalytic reactions. The reactions discussed in this review are classified into two types: (1) the reactions mainly occurred on the external surface or in the pore mouths of the mesoporous ZSM-5 and (2) the reactions mainly occurred in micropores of ZSM-5. The external acid sites of mesoporous ZSM-5 enable the reactions involving bulky reactants that exceed the size of ZSM-5 micropores; and the presence of mesoporosity which improves the mass transport of reactants as well as products, reduces diffusion limitation and accelerates catalytic reaction. Although the advantages of mesoporous ZSM-5 compared with the conventional one are closely related to high external surface area and large mesopore volume, the acidity, including the type, strength and amount of acid sites and Al distribution, should be taken into account when the mesoporous ZSM-5 is utilized as catalyst in a real reaction. Finally, future challenges and opportunities for mesoporous ZSM-5 materials are presented. Keywords: Catalysis, mesoporous zeolite, ZSM-5.
ZSM-5
Mesoporous organosilica
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Mesoporous organosilica
Solid acid
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The refractive index is a key optical constant required by optical thin film designers. The coater-designer team must constantly verify the refractive indices of the non-absorbing optical thin films since the refractive index of a deposited material can vary by switching coating systems or operators as well as expected changes during the course of a coating run. A transmittance measurement on a spectrophotometer is an easy and accurate (usually to within {+-}0.5% spread) method of determining the refractive index. In one technique, the refractive index is obtained from visually curve-fitting a calculated (using a thin film design program and selecting the refractive index) transmittance spectrum to the measured transmittance spectrum. There are two other techniques which are discussed in this report: A quick, approximate method vs. the exact derivation. What the authors have not been able to find in the literature is the exact transmittance dependence as a function of the refractive indices (layers) through which the light passes and which accounts for the substrate back reflections. There are undocumented approximation methods as well as one in the literature by Cheremukhin and Rozhnox. Otherwise, most texts either derive the transmittances through optical multilayers or just the effect of back reflections on the transmittance for thick substrates. Without correcting for substrate back reflections, the derived refractive indices from the measured transmittances are in error by as much as 10%. In this work, the authors have utilized both an exact and an approximate method of determining the refractive index of the film. It is found that both the exact and approximate methods of determining the refractive index of thin optical coatings are within the measurement errors of commercially available spectrophotometers.
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