IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
Not a member yet
4657 research outputs found
Sort by
Visible light driven degradation of brilliant green dye using titanium based ternary metal oxide photocatalyst
No full textWe report a novel copper and cobalt impregnated titanium based ternary metal oxide nanocomposite (CuCO0.5Ti0.5O2) synthesized via simple chemical method. X-ray diffraction pattern and SAED pattern reveals the well crystallinity (R (3) over tildem space group) and phase purity of the synthesized sample. TEM micrograph shows the nano size and heterostructure of the product. Nanoporous nature of the synthesized product is observed from BET analysis. The incorporation of the copper and cobalt in titanium oxide nanoparticle host modifies the band gap of the host and a broadband absorption spectrum (similar to 325 nm to 800 nm) of the nanocomposite is observed from the UV-Vis-NIR absorption spectroscopy analysis. Photoluminescence (PL) spectrum confirms generation of sufficient electron-hole pairs which could actively participate in photodegradation activity. Photocatalytic performance of the product has been investigated by degrading brilliant green (BG) dye, which shows excellent activity with increased catalytic material loading. The photocatalytic activity is enhanced at high pH level of the solution. Reusability experiments confirms that the catalyst material is reusable with almost same efficiency for degrading BG dye. Wavelength selective photocatalytic degradation of BG dye reveals that the CuCO0.5Ti0.5O2 nanocomposite shows the highest activity under blue-green illumination
Activating ZnO nanorods photoanodes in visible light by CdS surface sensitiser
Get PDFThin films of c-axis aligned uniform ZnO nanorods (NRs) were fabricated on to fluorine-doped tin oxide-coated soda lime glass substrate by a two-step chemical route. Thereafter ZnO NRs/CdS core shell structures were successfully synthesised by depositing CdS layer on top of vertically aligned ZnO NRs using less hazardous nanocrystal layer deposition technique. The presence of CdS in ZnO NRs/CdS core shell structures was confirmed by energy dispersive X-ray analysis. Examination of structure and morphology of the fabricated films by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) revealed that both films have one-dimensional hexagonal wurtzite structure. Optical properties evaluated from ultraviolet-visible and photoluminescence spectra demonstrated better photo response of ZnO NRs/CdS core shell structure with respect to bare ZnO NR structure. Optical to chemical conversion efficiency of ZnO NRs/CdS photoanode was found to be similar to 1.75 times higher than bare ZnO NRs photoanode in photo electrochemical water splitting under visible light
Development of non-shrinkable ceramic composites for use in high-power microwave tubes
No full textAl2O3-CaO-SiC-based ceramic composites with four different compositions were sintered at 1700 degrees C for 3 h in an air furnace. The phase analysis, microstructural characterization, and elemental composition determination of the developed composites were performed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDAX) analysis, respectively. The shrinkage, thermal properties, and electrical resistivity of the composites were also studied. The experimental results showed the effects of adding silicon carbide and calcia to alumina on the thermal, electrical, and shrinkage properties of the resultant composites. Among the four investigated ceramic composites, the one composed of 99wt% alumina, 0.5wt% CaO, and 0.5wt% SiC exhibited the best characteristics for use as a potting material in a dispenser cathode of a microwave tube. The material exhibited slight expansion instead of shrinkage during drying or firing. Other properties of the composite powder, such as its thermal properties and electrical resistivity, were comparable to those of a commercial alumina powder
Frequency upconversion mechanism in Ho3+/Yb3+-codoped TeO2-TiO2-La2O3 glasses
No full textFrequency upconversion from Ho3+/Yb3+-codoped glass or crystal under Yb3+ sensitization is a known phenomenon. However, inconsistencies are prevalent in the understanding of double energy transfer mechanisms for Ho3+/Yb3+-codoped systems. In this context, rate equations are proposed for Ho3+/Yb3+-codoped low-phonon TeO2-TiO2-La2O3 glass under Yb3+ sensitization with continuous and pulsed excitations. The proposed rate equations are validated with experimental results to elucidate the mechanisms responsible for populating (5)(S-2, F-4) and F-5(5) energy levels of Ho3+ ion. The solutions of rate equations with experimental results are substantiating the occurrence of both excited state absorption (ESA) and energy transfer upconversion (ETU) mechanisms in populating Ho3+:5(S-2, F-4) level, though higher concentration of Ho3+ ion would decrease the probability of ETU and increase of ESA. In contrast, Ho3+:5F5 level has been populated via ETU only. Numerical solutions to the rate equations are also proposed to elucidate the mechanics for populating (5)(S-2, F-4) and F-5(5) levels of Ho3+ ion. The proposed rate equation for pulsed excitation explains the characteristics of respective decay curves, which are further used to quantify energy transfer coefficient (W-02) as (1.77 +/- 0.12)x10(-17)cm(3)s(-1) for Ho3+/Yb3+-codoped TTL glass host
Doping induced modification in magnetism and magnetoelectric coupling at room temperature in Fe2Te(1-x)NbxO6
No full textThe polycrystalline Fe2TeO6 (FTO) and Fe2Te(1-x) NbxO6 x= 0.5 (FTON5), x= 0.10 (FTON10)] is prepared via solid state reaction route. Comparative structural study is done by the Rietveld refinement of the powder X-ray diffraction data of all the prepared samples. We observe the presence of ferroelectricity in FTO via remanent polarization versus electric field (PE) hysteresis loop measurement with remanent polarization similar to 4.85 nC/cm(2). On application of 1.2 T external magnetic field, this observed remanent polarization changes 60% which confirms the presence of magnetoelectric (ME) coupling in the material. The magnetic field dependent PE loops also confirms the presence of ME coupling in both FTON5 and FTON10. In case of FTON10 the remanent polarization changes by 80% on application 1.2 T. The presence ME coupling is also observed through the nonlinear magnetoelectric voltage response on application of modulated DC magnetic field in both FTO and FTON5. This nonlinear voltage response changes to linear behavior for FTON10 due to Nb doping
An in vitro evaluation of the variation in surface characteristics of bioactive glass coated SS316L for load bearing application
No full textThe present communication reports the variation in surface characteristics of bilayered coating of phosphate free bioactive glass (PFBG) on SS316L substrate at simulated conditions, w.r.t both pH and temperature, to understand the suitability of the same for load bearing applications. The coated substrates were subjected to both physiological (7.4) and pathophysiological (4.5) pH conditions, considering two working temperatures of 37 degrees C and 45 degrees C, related to the real time scenario, in the post implantation period. Herewith, a faster dissolution of the PFBG network could be obtained `at higher temperature (45 degrees C) and acidic pH (4.5) conditions, leading to a degraded surface texture, while the same at 37 degrees C and pH 7.4, exhibited an almoit intact surface. The observation was corroborated using atomic force microscopy which exhibited an exponential increase in the nanoscale surface roughness of the coating at lower pH and at higher temperature conditions. The ionic Ca2+ dissolution kinetics of the PFBG coating followed by their cellular interaction were assessed using MC3T3 cell line, which showed a distinct difference compared to the as prepared PFBG coated substrate. Further, we made an attempt to assess the role of the calcium binding protein, calmodulin and its major target, calcium-calmodulin kinase II alpha (CAMKII alpha) in osteoblast (MC3T3) differentiation, cultured on the PFBG coated SS316L substrates, subject to the experimental parameters as abovementioned. The results indicated significance of the real time conditions at the site of application of a bioactive glass coating on load bearing SS316L based implant material
Facile synthesis of carbon fiber reinforced polymer-hydroxyapatite ternary composite: A mechanically strong bioactive bone graft
No full textCarbon fiber reinforced carboxymethyl cellulose-hydroxyapatite ternary composites have been synthesized by a simple wet precipitation method for weight bearing orthopedic application. Composites were synthesized with the incorporation of chemically functionalized carbon fibers. The functional groups onto the surface of fibers induced the formation of hydroxyapatite at the bridging position through which fibers were effectively bound with matrix. Consequently, the flexural strength and compressive strength of composite have reached to 140 MPa and 118 MPa, respectively. The flexural modulus of the composite is in the range of 9-22 GPa. In-vitro cell study showed that the composite possesses excellent cell proliferation and differentiation ability. With these excellent mechanical and biological properties, synthesized composite exhibits potential to be used as a mechanically compatible bioactive bone graft
Photocatalytic degradation of organic pollutant with polypyrrole nanostructures under UV and visible light
No full textConjugated polymer nanostructures (CPNs) emerge as a new class of photocatalysts for organic pollutant degradation under UV and visible light. Polyprrole (PPy), as a conjugated polymer, exhibits a wide range of applications. We present here the first demonstration of employing pure PPy nanostructures as a very efficient photocatalyst for water depollution. PPy nanostructures were synthesized in hexagonal mesophases (used as soft templates) by chemical polymerization (PPy-NS-c), obtained by radiolysis (PPy-NS-gamma), and synthesized without any template via chemical method (PPy-bulk) as bulk. The different PPy samples were characterized by SEM, TEM, FTIR and UV vis absorption spectroscopy. The photocatalytic activity of both PPy nanostructures (PPy-NSc and PPy-NS-gamma), which remain very stable after several cycles, was evaluated for the degradation of organic pollutant in aqueous solution (phenol and methyl orange were taken as a model pollutant). PPy nanostructures show high photocatalytic activity under both UV and visible light while bulk PPy (PPy-bulk) has no appreciable activity. PPy-NS-c present the highest activity for photodegradation of phenol under UV light, while PPy-NS-gamma exhibit the best photocatalytic activity under visible light. We demonstrate here that the nanostructuration of these polymers is an important factor for their application in photocatalysis
Eco-friendly lightweight filament synthesis and mechanical characterization of additively manufactured closed cell foams
No full textEnvironmentally pollutant fly ash cenospheres (hollow microballoons) are utilized with most widely consumed, relatively expensive high density polyethylene (HDPE) for developing lightweight eco-friendly filament for 3D printing of closed cell foams. Cenospheres (20, 40 and 60 by volume %) are blended with HDPE and subsequently extruded in filament to be used for 3D printing. Cenosphere/HDPE blends are studied for melt flow index (MFI) and Theological properties. MFI decreases with cenospheres addition. Complex viscosity, storage and loss modulus increase with filler loading. DSC results on the filament and printed samples reveal increasing crystallization temperature and decreasing crystallinity % with no appreciable change in peak melting temperature. Cooling rate variations exhibit crystallinity differences between the filament and the prints. CTE decreases with increasing cenosphere content resulting in lower thermal stresses and under diffusion of raster leading to non-warped prints. Micrography on freeze fractured filament and prints show cenospheres uniform distribution in HDPE. Intact cenospheres lower the foam density making it lightweight. Tensile tests are carried out on filaments and printed samples while flexural properties are investigated for 3D prints. Cenospheres addition resulted in improved tensile modulus and decreased filament strength. Tensile and flexural modulus of printed foams increases with filler content. Results are also compared with injection molded samples. Printed foams registered comparable tensile strength. Specific tensile modulus is noted to be increased with cenospheres loading implying weight saving potential of 3D printed foams. Property map reveals printed foams advantage over other fillers and HDPE composites synthesized through injection and compression molding
Soliton Molecules in Self-Mode-Locked Ring-Cavity Er/Yb Double-Clad Fiber Laser
No full textIn this paper, generation of soliton molecules by a self-mode-locked Er/Yb double clad fiber laser is experimentally demonstrated. The optical spectrum of the bound solitons exhibits eight well defined peaks at similar to 1563 nm with high modulation depth. The corresponding autocorrelation measurement shows a fundamental trace with several narrow peaks, suggesting the presence of bound solitons. The obtained results demonstrate the reliability of our simple laser configuration for the formation of more robust soliton molecules as the pump power is increased. The soliton molecules exhibit repetition rate of 19.54 MHz and average power of 1.2 W, achieved with a pump power of similar to 4.8 W