Refractive Index Of Coatings Research Articles

State primary standard of ellipsometric angles GET 186-2017

Paper describes the structure, principle of work and metrological characteristics of the State primary standard of ellipsometric angles units GET 186-2017, which provides measurement of the two-dimensional spatial distribution of ellipsometric angles. The GET 186-2017 includes a spectral ellipsometer equipped with a two-coordinate table for measurements on a grid of 10×10 points, and an interference profilometer which measures a two-dimensional map of deviations from 90° normal to the surface of the object. At scan points where the normal deviation exceeds 0.01° there are no measurements. Measurement of the two-dimensional spatial distribution of ellipsometric angles allows restoring the spatial distribution of the thickness and complex refractive index of coatings over the area. GET 186-2017 ensures the uniformity of measurements in priority areas of science and technology, such as microelectronics, optics, instrument making. The main consumers of GET 186-2017 are organizations involved in the development of new products of microelectronics, solar cells, optics, in particular laser gyroscopes. Such products includes ordered multilayer structures deposited on substrates, which are controlled using various types of ellipsometers, including image ellipsometers.

Rational design and fabrication of highly transparent, flexible, and thermally stable superhydrophobic coatings from raspberry-like hollow silica nanoparticles

Multifunctional coatings with superhydrophobicity, high transparency, thermal stability, flexibility, and ultralow refractive index have been investigated for many years. They have promising applications in industries such as in electronic and optical devices, photonic materials, and templates for fabricating biological and chemical sensors. However, the relatively complex preparation technology of these coatings or difficult to possess these properties simultaneously are still the main factors that limit their wide application. In this paper, we report a facile atmospheric approach to create transparent multifunctional raspberry-like particulate coatings with a low refractive index, which were obtained via one-pot base-catalyzed sol-gel process using tetraethyl orthosilicate (TEOS) and 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (POTS) as co-precursors. The excellent superhydrophobicity, mechanical flexibility, self-cleaning property, thermal and chemical stability of the as-fabricated coatings were demonstrated. The refractive indices of coatings can be easily tuned at a range of 1.07–1.16. Particularly, the resulted samples on the K9 glasses exhibited superhydrophobicity with a water contact angle (WCA) of 162° when the scale ratio of the POTS and TEOS was 1.0. The superhydrophobicity of the as-prepared coatings could last for more than half a year under indoor condition, demonstrating the long stability of the superhydrophobicity. Furthermore, we demonstrated that this simple efficient method could be extended to different substrates, including K9 glass, Polyvinyl chloride (PVC), stainless steel, aluminum alloy, and gingko leaf, to achieve superhydrophobicity. Interestingly, the superhydrophobicty of the coatings transferred to superhydrophilicity (WCA < 5°) by calcination at 500 °C, which resulted in a good antifogging property. Moreover, the coatings were not sensitive to the strong acid (pH = 1) and kept their superhydrophobic state for a long time (over 80 min). The coatings on PVC retain their excellent water-repellency after multiple bending cycles. Also, these coatings produced a fair transparency consisting of more than a 2.0% increase in optical transmittance in the visible-near infrared spectral range. Our study is promising building blocks for large-area, mechanical flexible, ultralow-refractive-index, superhydrophobic and environment-resistant surfaces.

One-step sol-gel preparation of ultralow-refractive-index porous coatings with mulberry-like hollow silica nanostructures

Nowadays, intense research efforts are directed toward the development of novel preparation high-quality ultralow-refractive-index coatings. Herein, we report a facile atmospheric process to fabricate ultralow refractive index porous coatings with mulberry-like hollow silica nanostructures. The coatings were fabricated by a one-step base-catalyzed sol-gel method using 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (POTS)221H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (POTS). and tetraethyl orthosilicate (TEOS)33Tetraethyl orthosilicate (TEOS). as co-precursors. The ultralow-refractive-index coatings could be obtained without any pretreatment (such as HF etching on the glass substrates) or post-treatment (such as the calcination to remove template), which is why it is suitable for large-area processing. Compared with previous methods, the procedure of this technique is simpler and more environmentally friendly. The refractive indexes of the coatings could be adjusted from 1.08 to 1.17. The effect of POTS amounts on the refractive index of coatings was investigated. Specifically, a possible particle growth mechanism of the fluoro-containing hollow silica nanoparticles (FHSNs)44Fluoro-containing hollow silica nanoparticles (FHSNs). sols was proposed. Furthermore, the water-repellent properties were also investigated. The ultralow-refractive-index coatings with porous silica microstructures have the advantages of abundant porosity, thus, they are promising to find potential applications in energy-stored materials and porous medium.

Assessment of the sensitivity of core / shell parameters derived using the single-particle soot photometer to density and refractive index

Abstract. Black carbon (BC) is the dominant absorbing aerosol in the atmosphere, and plays an important role in climate and human health. The optical properties and cloud condensation nuclei (CCN) activity of soot depend on the amounts (both relative and absolute) of BC and non-refractory material in the particles. Mixing between these two components is often represented in models by a core / shell coated sphere. The single-particle soot photometer (SP2) is one of, if not the only, instrument capable of reporting distributions of both core size and coating thickness. Most studies combine the SP2's incandescence and 1064 nm scattering data to report coating properties, but to date there is no consistency in the assumed values of density and refractive index of the core that are used in these calculations, which can greatly affect the reported parameters such as coating thickness. Given that such data are providing an important constraint for model comparisons and comparison between large data sets, it is important that this lack of consistency is addressed. In this study we explore the sensitivity of the reported coatings to these parameters. An assessment of the coating properties of freshly emitted, thermodenuded ambient particles demonstrated that a core density of 1.8 g cm−3 and refractive index of (2.26–1.26i) were the most appropriate to use with ambient soot in the Los Angeles area. Using these parameters generated a distribution with median shell / core ratio of 1.02 ± 0.11, corresponding to a median absolute coating thickness of 2 ± 8 nm. The main source of statistical error in the single-particle data was random variation in the incandescence signals. Other than the sensitivity to core refractive index, the incandescence calibration was the main source of uncertainty when optically determining the average coatings. The refractive index of coatings was found to have only a minor influence. This work demonstrates that using this technique the SP2 can accurately determine the average mixing state (externally or internally mixed) of ambient soot within the precision of the instrument calibration. Ambient coatings were measured up to a median shell / core ratio of 1.50 ± 0.11, meaning that this technique is able to resolve absolute changes in mixing state. However, when different core parameters were used, the core / shell ratio and the coating thickness were shown to be offset by amounts that could be larger than the atmospheric variability in these parameters, though the results have a similar precision. For comparison, using the core parameters that resulted in the thickest coatings, on the same thermodenuded fresh particles as before, generated a median shell / core ratio of 1.39 ± 0.11, corresponding to a median absolute coating thickness of 30 ± 8 nm. These results must be taken into account when comparing BC coatings measured using this technique, or if using these data for optical or CCN calculations. We have determined the most appropriate values of BC density and refractive index to use to measure mixing state at 1064 nm where particle morphology has only a minor effect, but appropriate values to use for optical calculations of nonspherical particles at visible wavelengths will also be subject to similar, significant uncertainties. Without similar constraints as those provided here, constraining the behaviour of BC particles in models using field data will be subject to large systematic measurement uncertainties.

Modeling analysis of gradient-index coatings prepared by reactive magnetron sputtering

The formation mechanism of gradient-index coatings by reactive magnetron sputtering is discussed. A practical modeling of gradient-index coatings is propose d, the relationship between refractive index of coatings and pressure of reactiv e gas is established. Next, we discussed the changing rule of partial-pressure o f reactive gas with time requivcd for obtaining a desired refractive index of g radient coatings under specific deposition conditions. A linear coating is tak en as example to illustrate how to get the relationship between partial-pressure of reactive gas and time.