IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Graphene oxide grafted hyperbranched poly (vinyl imidazole) with ionic liquid components as a potential carbon dioxide scrubber
No full textThe present work focuses on the design of a CO2 scavenger, capable of adsorbing a low concentration of CO2 from a mixed gas composition. Typically, vinyl imidazole and an ionic liquid brancher were copolymerized by ``Strathclyde methodology'' and grafted from graphene oxide; GO-g-(HB) PVIm-co-PIL (Cl). The chain transfer agent maintained short chains and developed hyperbranched architecture in GO-g-(HB) PVIm-co-PIL (Cl). The structure and the properties of GO-g-(HB) PVIm-co-PIL (Cl) was established from FTIR, (HNMR)-H-1, Raman, XRD and rheology. A metathesis reaction was carried out to exchange chloride anions with hexafluorophosphate anions; GO-g-(HB) PVIm-co-PIL (PF6). GO-g-(HB) PVIm-co-PIL (PF6) selectively captured a low concentration of CO2 from a mixed gas. The surface functionalities/properties of GO, hyperbranched architecture, porosity, nitrogen content and surface charge distribution together played a significant role in efficient and selective CO2 capture
Manipulation of infrared dispersive waves incustomized microstructured optical fibers for 1.7and 2.0 μm light sources
No full textWe demonstrate the controllable generation of infrared dispersive waves (DWs) from customized, in-house fab-ricated silica microstructured optical fibers (MOFs) by manipulating the location of zero dispersion wavelength(ZDW) through the structure of the fibers. The highly enriched shaping mechanism of arrested soliton in the MOFswith two ZDWs provides a technique for efficient energy transfer into the targeted eye-safe wavelengths at 1.7 and2.0μm by the virtue of DW formation
A novel ppm level ethanol sensor based on La loaded ITO impregnated with Pd and Sb additives
No full textThe present work reports on a novel resistive ppm level ethanol sensor, prepared from nanocrystalline lanthanum loaded indium tin oxide (ITO) impregnated with palladium and antimony additives. A simple unique gel calcination process was adapted to synthesize the nanocomposite powders from their water based precursor salts. This was followed by detailed material characterizations through X-ray diffractometer, FESEM, TEM, EDX and XPS analyses. Fabricated Taguchi type sensor with an optimum concentration of Pd exhibited an excellent sensing performance towards a wide concentration range of (1-100 ppm) ethanol vapour. The sensor showed similar to 87% sensing response for 10 ppm ethanol vapour at an operating temperature of 300 degrees C. Even at 1 ppm concentration, similar to 53% response was observed with fast response and recovery time. The sensing action has been elucidated as the catalytic oxidation of ethanol to carbon di oxide over the La loaded ITO surface layer that resulted in electron transfer to the indium tin oxide site. In addition, synergistic effect of palladium and antimony enhanced the sensing performance as well as reduced the base resistance of the sensor by chemical/electronic sensitization and increasing carrier ion concentration respectively. Comparatively low resistance, negligible cross sensitivity, quick response/recovery time and good long term stability makes the sensor suitable for deployment in practical applications
Radiation stability of ceramic tubular membranes containing ammonium molybdophosphate (AMP) for the application of radio-cesium recovery from radioactive wastes
No full textIn order to develop radiation resistant membranes for the treatment of high level waste (HLW), ceramic tubular membranes were prepared by incorporating varying amounts of ammonium molybdophosphate (AMP), known for efficient Cs(I) uptake from acidic feeds, for the recovery of radio-caesium. The sorption of Cs(I) onto the membrane increased linearly with increasing the AMP content (10%-40%). Radiation stability of the membranes was evaluated by exposing them to gamma radiation obtained from a(60)Co source. The composite ceramic material showed excellent radiation stability without any morphological change up to 1100 kGy, indicating its potential application in radioactive waste treatment. For 10% AMP loaded ceramic membrane, the Cs(I) sorption decreased linearly with radiation dose. However, Cs sorption was not altered up to 1100 kGy dose for 20% and 40% loaded AMP
Fabrication of Germanium-on-insulator in a Ge wafer with a crystalline Ge top layer and buried GeO2 layer by oxygen ion implantation
No full textThe paper reports fabrication of Germanium-on-Insulator (GeOI) wafer by Oxygen ion implantation of an undoped Ge wafer of orientation (100). O+ ions (energy 200 keV) were implanted to a fluence of 1.9 x 10(18) ions-cm(-2) and the implanted wafer was subjected to Rapid Thermal Annealing. The resulting wafer has a top crystalline Ge layer of similar to 220 nm thickness and resistivity approximate to 32 Ohm-cm and a buried Oxide layer (BOX) of crystalline GeO2 (thickness approximate to 0.62 mu m). The crystalline GeO2 layer has hexagonal crystal structure with lattice constants close to the standard values. Raman Spectroscopy and cross-sectional electron microscopy established that the top Ge layer was recrystallized during annealing with a residual tensile strain of around +0.4% and an estimated dislocation density of 2.7 x 10(7) cm(-2). The crystallinity and electrical characteristics of the top layer and the quality of the BOX layer are such that it can be utilized for device fabrication
Processing of hydroxyapatite and its composites using ceramic fused filament fabrication (CF3)
No full textIn this article, we report the fabrication of hydroxyapatite (HAp) and its composites with 7.75 vol% Si3N4 (HAp10SN) using ceramic fused filament fabrication (CF3). Homogeneous feedstock with 40 vol% ceramic powder was prepared and used to extrude filaments for further printing using a desktop printer. Our results showed that the addition of Si3N4 to HAp increases the feedstock viscosity. However, the filaments and CF3 parts made using HAp and HAp10SN feedstocks exhibited comparable densities without gross defects. We have obtained relatively smoother CF3 parts with HAp10SN than pure HAp, which is attributed to their high feedstock viscosity and formation of liquid phase during sintering. Sintering at 1250 degrees C for 4 h in air, after thermal debinding, resulted in a relative density of-85% with HAp and tricalcium phosphate (TCP) as major constituents. Sintered HAp10SN samples also revealed almost 70% reduction in the grain size and 4-fold increase in the hardness compared to pure HAp. Our results indicate that the CF3 processed HAp10SN samples containing-15% porosity, Si3N4 particles and Si-substituted HAp/TCP have strong potential as bone replacements
In Situ-Grown Cdot-Wrapped Boehmite Nanoparticles for Cr(VI) Sensing in Wastewater and a Theoretical Probe for Chromium-Induced Carcinogen Detection
No full textIn modern society, massive industrialization escalates environmental degradation by liberating various contaminants into the environment. Hexavalent chromium is a heavy metal that is being discharged from tannery and other industries, resulting in various carcinogenic diseases. This study reports a carbon dot (cdot)-based fluorometric probe for detecting hexavalent chromium in water. This is the very first time that cdots are tailored over the boehmite nanoparticle's surface using an in situ approach. Validation of formation of the nanocomposite has been discussed in detail employing the Rietveld refinement-based X-ray crystallography method. Vibrational spectroscopy and electron microscopy of the sample authenticate the nucleation process and the growth mechanism. The Stern-Volmer approach and time-resolved fluorescence measurements justify the sensitivity of the sensor (similar to 58 nM), and selectivity is analyzed by exposing the material to different ionic environments. Density functional theory (DFT) is applied herein to analyze the origin of fluorescence and the sensing mechanism of the probe, which shows that photoinduced electron transfer is responsible for the turn-off-based sensing of Cr(VI). The molecular docking simulation is carried out to ensure the binding of cdots to the binding pocket of the glutathione enzyme, which is responsible for treating reactive oxygen species-mediated DNA damage due to elements such as hexavalent chromium. Time-dependent density functional calculations show that the fluorometric probe is capable of detecting Cr(VI) in living cells making it an early stage chromium-mediated carcinogen detector
Effects of Mg% on open circuit voltage and short circuit current density of Zn1-xMgxO/Cu2O heterojunction thin film solar cells, processed using electrochemical deposition and spin coating
No full textZn1-xMgxO/Cu2O/Ag solar cells were fabricated upon fluorine doped tin oxide coated soda lime glass substrate with varying percentage of Mg mol% doping in zinc oxide (ZnO) layer. Short circuit current density & open circuit voltages of the fabricated cells were investigated. Optimum doping with Mg improved the transparency of ZnO layer which helped in increasing the short circuit current density of solar cells. An enhancement of open circuit voltage was observed with increase in x, which was investigated using X-ray photoelectron spectroscopy and the results revealed that with increase in x, there was a decrease in conduction band offset between Zn1-xMgxO and cuprous oxide layers. From UV-Visible transmittance spectra, it was observed that with Mg doping in ZnO nanostructure, optical losses were reduced which resulted in increase in Short circuit current density. The objective of this study was to investigate and develop a technology for fabrication of solar cells that is both cost effective and easy to produce
Large Magnetoelectric Coupling in the Thin Film of Multiferroic CuO
Get PDFWe report observation of large magnetoelectric coupling in an epitaxial thin film of multiferroic CuO grown on the (100)MgO substrate by the pulsed laser deposition technique. The film is characterized by X-ray diffraction, transmission electron microscopy, and Raman spectrometry. The crystallographic structure of the film turns out to be monoclinic (space group C2/c) with 111]CuO parallel to100]MgO ``out-of-plane'' epitaxy and ``in-plane'' domain structure. The lattice misfit strain is found to vary within +/- 1-3%. The dc resistivity, magnetization, dielectric spectroscopy, and remanent ferroeletric polarization have been measured across 80-300 K. The dielectric constant is found to decrease by >20% under a moderate magnetic field of similar to 18 kOe while the remanent ferroelectric polarization, emerging at the onset of magnetic transition (T-N similar to 175 K), decreases by nearly 50% under similar to 18 kOe field. These results could assume importance as the strain-free bulk CuO does not exhibit magnetoelectric coupling within such magnetic field regime. The strain-induced large magnetoelectric coupling in the CuO thin film would generate new possibility of further strain tuning to observe room-temperature magnetoelectric multiferroicity suitable for scores of applications such as memories, sensors, energy-harvesting devices, generators, amplifiers, and so forth
Surfactant and catalyst free facile synthesis of Al-doped ZnO nanorods - An approach towards fabrication of single nanorod electrical devices
No full textClassical models illustrate the genesis of bottom-up techniques for synthesis of pristine ZnO or Al-doped ZnO nanoparticles via surfactant aided or hydrothermal chemistry, to constitute the fundamental modules of nanotechnology and nanodevices. The present study demonstrates a facile as well as surfactant and catalyst free route for synthesis of morphology controlled Al-doped ZnO nanorods. Morphological evaluation (via FESEM and TEM characterization) clearly verifies the successful synthesis of ZnO and Al-doped ZnO nanorods. Moreover, crystallographic and FTIR studies ratified presence of multiple different planes as well as phases of ZnO and Al-doped ZnO nanostructures, eventually confirming the doping process. Further, the alteration in mode of electronic transition and surface charge of ZnO nanorods post doping with Al was witnessed from its UV-visible or photoluminescence spectra and zeta potential measurements, respectively. Electrical measurements were performed on prepared Al-doped ZnO nanorods which were fabricated as single nanorod devices. Owing to substitutional and interstitial doping, the electrical conductivity of the devices was drastically enhanced after doping. Excellent electrical attribute of the nanorods when fabricated into single nanorod device was indicative of its potential to be deployed as next generation nano-biosensors or piezo-electric devices