IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Extremely high temperature stable nanometric scale multilayer spectrally selective absorber coating: Emissivity measurements at elevated temperatures and a comprehensive study on ageing mechanism
No full textSpectrally selective W/WAlSiN/SiON/SiO2 solar absorber coatings were sputter-deposited on stainless steel and silicon substrates. The optimized as-deposited sample exhibits a high solar absorptance of 0.955 and a low thermal emissivity of 0.10 at 82 degrees C. The coating exhibits a very low reflectance of 1.2% in the wavelength range of 0.5-1.5 mu m in the solar spectrum. The spectral emissivity measurements at various operating temperatures and with varying emergence angles were investigated. Also, the impact of emissivity on the photothermal efficiency at different temperatures of the developed solar absorber coating was calculated. The calculated optical properties of the as-deposited sample exhibited low thermal emissivity of 0.157 (at 500 degrees C) and a high heliothermal efficiency of 89.5%. Angular reflectance measured at room temperature illustrates an insignificant change in the hemispherical and near normal emissivities of the samples. In addition to these studies, the ageing tests of the as-deposited samples at various operating temperatures were studied in detail. The thermal ageing tests of the samples in air and vacuum environments indicated excellent thermal stability at elevated temperatures, i.e., in air at 400 degrees C for 500 h, at 450 degrees C for 175 h and at 500 degrees C for 100 h, whereas, in a vacuum it was stable at 700 degrees C for 200 h. The top anti-reflection layers and the fine nano-multilayers of WAlSiN (W2N and AlSiN) prevent the inward diffusion of oxygen and thereby improve the overall thermal stability of the tandem absorber
Tribocorrosion characteristics of Ti6Al4V-TiB-TiN in-situ composite coatings prepared using plasma spraying
No full textTi6Al4V alloy composite coatings in-situ reinforced with TiB-TiN were deposited on Ti substrate using plasma spraying. Influence of plasma power (50 and 60 kW) and deposition speed (40 and 50 mm/s) on coating microstructure and bio-tribocorrosion performance was analyzed. Process parameters found to have strong influence on the tribocorrosion behavior and the material loss/damage of these coatings was found to be significantly less than that of Ti substrate. However, corrosion played a dominant role in affecting the wear and overall damage of all materials. Present in-situ composite coatings reinforced TiB-TiN exhibited superior tribocorrosion resistance than Ti substrate as a result of their high hardness and non-passivating nature
Room temperature acetone sensing performance of Pt/Sb2O3 impregnated Fe2O3 thin film: Noninvasive diabetes detection
No full textIn the present report, an enhanced sub-ppm level acetone sensing performance of a novel Pt and Sb2O3 impregnated nanocrystalline Fe2O3 thin film operating at room temperature has been explored. Starting from organic precursor sols, thin films of thickness - 6 ?m were drop-casted on planar alumina substrates preattached with the platinum electrodes and cured at - 350?C. The characterizations of the materials have been carried out using X-ray Diffraction, FTIR, Raman Spectroscopy, micro structural study through FESEM and TEM as well as XPS analyses. The sensing characteristics including sensing response, lowest detection limit, recovery time etc. of these chemiresistive thin films were studied on exposing them to various concentrations (0.25 to 1 ppm) of acetone at room temperature. The sensing response of -2.4 with - 95 s recovery time was observed on exposure to 1 ppm acetone for 10 s. Even at 0.25 ppm acetone, the response observed - 1.4. Selectivity study on different alcohols and other interfering gases of breath has also been tested. Additionally, a real time breath acetone measurement was carried out and acetone sensing mechanism has been elucidated
Kinetics and mechanism of arsenic removal using sulfide-modified nanoscale zerovalent iron
No full textSulphur modified nano zerovalent iron (S?nZVI) has shown considerable promise for removal of various aqueous contaminants. However studies utilizing S?nZVI for removal of aqueous inorganic arsenic (As) is relatively rare, which was studied in this work. Characterization of the synthesized S?nZVI showed typical core-shelled structure with distorted outer shell consisting of iron oxide and FeS. The removal rate of both As(III) and As(V) by S?nZVI was considerably enhanced compared to nZVI and highest As removal was observed at S/Fe ratio of 0.1 under acidic condition. Results showed slight decrease in As removal efficiencies for S?nZVI aged upto 48 h, with obvious drop in As removal efficiencies for longer aging time which although still exhibited higher reactivity than bare nZVI. Spectroscopic investigation showed sulphur amendment of nZVI completely altered the As sequestration mechanism compared to nZVI. While reduction of the adsorbed As(III) and As(V) was observed for bare nZVI, in contrast, uptake of As(III) and As(V) by S?nZVI involves adsorption as As(III) and As(V) oxyanion respectively with additional precipitation of As2S3. Overall, the study shows that incorporation of FeS on the surface of nZVI can be an effective modification strategy for efficient sequestration of As from contaminated water
High-efficiency picosecond mode-locked laser using a thulium-doped nanoengineered yttrium-alumina-silica fiber as the gain medium
No full textWe report the theoretical and experimental investigation of a self-starting mode-locked fiber laser with a nanoengineered Tm 3 +-doped yttrium-alumina-silica (YAS) fiber as the gain medium. The YAS fiber exhibits a higher capability of Tm3+ cluster elimination than commercial silica fibers. The Tm3+ fluorescence properties and YAS dispersion are well characterized. As a result, an efficient picosecond mode-locked fiber laser is demonstrated with a slope efficiency of 14.14% and maximum pulse energy of 1.27 nJ. To the best of our knowledge, this is the first mode-locked fiber laser based on a Tm3+-doped YAS fiber. The experimental observation is also supported by the numerical analysis. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
Highly radiation resistant room temperature organic perovskite halide (FAPbI(3)) crystal for direct detection of gamma-ray photons down to nano curie activity
No full textWe report a simple room temperature gamma (gamma)-ray detector with electrical read out made using as-grown highly textured crystals of organic perovskite halide formamidium lead iodide (FAPI) prepared by solution method. The detector uses electronics that measure resistance changes, similar to those used in optical detectors. Although it does not have energy resolution, the detector can be used as a quick tool to detect the presence of gamma-ray in wide energy range, from the 100 to the 1250 keV range, with noise limited sensitivity capable of detecting activity down to 50 nCi. The FAPI detector has a reasonable mu tau approximate to 5.2 x 10(-3)cm(2)V(-1) gamma-ray making it useful in applications needing such long exposure. Also, a proof of concept has been established toward wearable, low cost, portable solid state gamma ray detectors using paper electronics based halide perovskites
Synthesis and Investigation of Multicomponent Chalcogenide Glasses for Mid/Far Infrared Transmission and Electrical Properties
No full textOxide glasses have always been playing an important role due to their excellent thermal, mechanical and optical properties. These glasses possessing such excellent qualities lacks
the extended transmission in infrared (IR) region beyond 5-6 µm which gave rise to
important class of non-oxide glass referred as chalcogenide glass. As the name suggests,
chalcogenide glasses are composed of chalcogens such as sulphur, selenium or tellurium as
one of the important network former and synthesised stringently in the absence of oxygen.
The glasses containing either of these chalcogens or/and in combination with other
elements form a most interesting and widely studied chalcogenide glass family with many
attractive properties in the field of mid/far infrared photonics in the last century. Their
homopolar and heteropolar bond formation, low phonon energy, high refractive
index,excellent transparency in infrared and their easy moulding nature due to less Tg
made them the suitable candidates for many applications such as thermal imaging, phase
change memory devices, infrared optics etc. Low optical losses and wide transparency
range are the main properties that are achievable in chalcogenide glasses due to absence of oxygen (O2). There are different sulphur based chalcogenide glasses that have good thermal and mechanical properties but their optical transmission is limited to 10 m only. Addition of halides such as iodine (I) helps in shifting their mid-infrared cut-off beyond 11µm and halide containing sulphide glasses can be potential candidates for thermal imaging or night vision applications due to their good thermal and mechanical properties. Space exploration to search for chemical signature of life in different planets has drawn the attention towards the development of materials capable of sensing atmospheric carbon dioxide (CO2) and it led to the development of selenium containing tellurium rich
chalcogenide glasses. Telluride glasses possess large transmission window along with
unique property of good electrical conductivity and favourable thermal properties. These
properties make them good optical component and as well as an electrode. There are many
biomolecules which are present in our body have their fingerprint around 13-16 µm
wavelength range, and these glasses being transparent well beyond 16 µm will be the best
and suitable candidate for far-infrared or biomedical applications. The addition of tetrahedral germanium or trivalent arsenic or antimony to tellurium rich glasses enhances
thermal and mechanical properties which are suitable systems for far-infrared
applications.
In present work, the aim is to achieve a glasses with mid-infrared transmission cut off
beyond 11 µm by adding iodine in sulphide glass systems. For far-infrared applications,
approach to synthesise glasses with well extended cut-off beyond 16 µm by diminishing
impurities has been successfully fulfilled by achieving appropriate thermal and mechanical
properties. Electrical properties were also explored by adding silver iodide (AgI) in both
sulphide and selenide-telluride based chalcogenide glass systems
Highly efficient mode-locked and Q-switched Er3+-doped fiber lasers using a gold nanorod saturable absorber
Get PDFMode-locked and Q-switched pulsed fiber laser sources with wavelengths of 1.55 mu m are widely used in various fields. Gold nanorods (GNRs) have been applied in biomedicine and optics owing to their biocompatibility, easy fabrication, and unique optical properties. This paper presents the analysis of a saturable absorber based on a colloidal gold nanorod (GNR) thin film for dual-function passively mode-locked and Q-switched 1.55-mu m fiber lasers. The colloidal GNR thin film possesses superior properties such as a wide operating wavelength range, large nonlinear absorption coefficient, and a picosecond-order recovery time. Its modulation depth and saturation intensity at 1.55 mu m are 7.8% and 6.55 MW/cm(2), respectively. Passive mode-locked or Q-switched laser operation is achieved by changing the number of GNR thin-film layers. The advantages of these high-quality GNRs in mode-locked and Q-switched fiber lasers with record-high slope efficiency are verified by conducting comprehensive material and laser dynamic analyses. The self-starting mode-locked fiber laser with an efficiency as high as 24.91% and passively Q-switched fiber laser with the maximum energy of 0.403 mu J are successfully demonstrated. This paper presents the novel demonstration of reconfigurable mode-locked and Q-switched all-fiber lasers by incorporating colloidal GNR thin films
Effect of Yb2O3 and TiO2 on reaction sintering and properties of magnesium aluminate spinel
No full textMagnesium aluminate spinel with an initial MgO: Al2O3 molar ratio of 2:1 was prepared from its constituent oxides through a solid-state sintering process at temperatures ranging from 1550 to 1700 degrees C in a normal air atmosphere. The effect of varying amount (0.25-1.0 wt%) of TiO2 and Yb2O3 on densification, phase assemblage, mechanical, thermo-mechanical properties and microstructure of magnesia-rich spinel were investigated under static heating condition. The addition of TiO2 and Yb2O3 favours the densification of magnesia-rich spinel, which is discernible up to 1650 degrees C. This beneficial effect may be attributed to the development of the secondary phase and formation of solid solution due to the dissolution of the additive ions in the spinel structure. A marginal increase in the average grain size of the samples along with a narrower grain size distribution occurred with the incorporation of both the additives. Both the additives improved the mechanical properties of the magnesia-rich spinel; however, better room temperature flexural strength was achieved with Yb2O3 as compared to TiO2 addition. For the samples sintered at 1550 degrees C, 1.0 wt% Yb2O3 addition resulted in 30% increase in flexural strength; however, same amount of TiO2 addition increased the strength by 20%. In case of thermal shock resistance, 1.0 wt% TiO2 and 0.25 wt% Yb2O3 addition demonstrated promising result among all the samples
Space charge induced augmented dielectric permittivity and improved energy harvesting ability of nano-Ag decorated ZnSnO3 filled PVDF based flexible nanogenerator
No full textHere we report the effect of conducting Ag decoration on ZnSnO3 filler surface on the dielectric and mechanical energy harvesting performance of the resulting PVDF based composite films. The room temperature dielectric permittivity significantly enhanced for Ag@ZnSnO3 loaded PVDF compared to that of the ZnSnO3 loaded PVDF films through the effect of improved space charge polarization after Ag decoration on ZnSnO3 filler. The dielectric permittivity of the composite films was found to be increased gradually with the increase in the Ag concentration on ZnSnO3 filler surface. All the films exhibited low value of dielectric loss ((<)0.05 at 10 kHz) which proved their good applicability in flexible dielectrics. The improved polarization enhanced the mechanical energy harvesting performance of the composite films. The output peak to peak open circuit ac voltage (V-OC) for Ag@ZnSnO3-PVDF (5A10ZS) (with maximum Ag concentration on ZnSnO3 in the present experiment) film after repeated human finger tapping on it was found to be increased to similar to 20 V from a value of similar to 3.5 V and 11 V for neat PVDF and ZnSnO3-PVDF (5ZS) films, respectively. A 10 mu F capacitor was charged to similar to 3.8 V dc after rectification of output V-OC from 5A10ZS sample by 270 s of applied stress on it. During discharging, this dc electrical signal was able to light up some LEDs (connected in parallel) together instantaneously which proved the real life applicability of the nanogenerator device in self-powered flexible electronics