IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Study on the novel capacitive moisture sensing behaviour of nickel chromite nanoparticle based thick film
No full textIn this work, the novel and appreciable humidity sensing properties of microporous, spinel nickel chromite thick films are reported for the first time. NiCr2O4 microporous, thick film prepared by tape casting of sol-gel derived nanopowder followed by sintering was sandwiched between two parallel silver electrodes to develop capacitive humidity sensor. Condensation in the surface pores and physisorption on the sensor surface are found to be responsible for the humidity sensing properties. The sensor shows excellent humidity sensing properties in the range of 5% to 95% RH (relative humidity) with a resolution of similar to 3 pF/%RH in the lower humidity range (5%-30% RH) at 1 kHz external electric field. The sensor also exhibited excellent repeatability (at least 50 cycles of 5%-95%RH), good stability of at least 6 months, and low hysteresis loss. The thick film sensors were characterized by XRD, FT-IR, FESEM, TEM, EDX, and contact angle measurement. (C) 2020 Elsevier Ltd. All rights reserved
Extraordinary magnetic properties of double perovskite Eu(2)CoMnO(6)wide band gap semiconductor
No full textSome novel magnetic behaviours in double perovskite Eu2CoMnO6(ECMO) have been reported. The x-ray photoemission spectroscopy study shows the presence of mixed valence states of transition metal ions. The UV-visible absorption spectroscopic study suggests that the ECMO has a direct wide band gap. A second-order magnetic phase transition as a sudden jump in the magnetization curve has been observed around 124.5 K. The large bifurcation between the zero field cooling and field cooling, suggests existence of strong spin frustration in the system. The inverse DC susceptibility confirms the presence of the Griffiths like phase. Sharp steps in magnetization have been observed in theM-Hcurve at 2 K, which vanishes on increasing temperature. The AC susceptibility study demonstrates the Hopkinson like effect as well as the presence of volume spin-glass-like behaviour. The temperature dependent Raman spectrum shows the presence of spin-phonon coupling
Magnetron configurations dependent surface properties of SnO2 thin films deposited by sputtering process
No full textThe effect of balanced magnetron (BM) and unbalanced magnetron (UBM) configurations, in RF sputtering process, on the surface properties of SnO2 thin films has been investigated. X-ray photoelectron spectroscopy (XPS) Sn3d and O1s core spectra reveal that the films deposited at RF power of 250 W under BM configuration consist of Sn4+ oxidation states, while those deposited under UBM configuration consist of Sn4+ and Sn2+ oxidation states. This has been attributed to the migration of oxygen atoms from SnO2, resulting in the formation of Sn interstitial and oxygen vacancies. The contact angle (theta) recordings reveal that the UBM configuration results in more hydrophobic surface (140.6 degrees) of SnO2 thin films than that under BM configuration (129.6 degrees). Further, Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM) results indicate that the SnO2 thin films deposited under UBM configuration have better density with granular grains in comparison to that under BM configuration. The present studies establish the fact that magnetron configurations in sputtering process have significant impact on the surface properties of SnO2 thin films
A lithium-aluminosilicate zeolite membrane for separation of CO(2)from simulated blast furnace gas
No full textIn this study, for the first time, the small pore size (0.28 x 0.37 nm) Li-aluminosilicate zeolite membrane was synthesized for separation of CO(2)from H-2-CO(2)and H-2-CO2-N-2-CO (simulated blast furnace gas) gas mixtures. Li-aluminosilicate membranes were prepared on porous clay alumina tubes by sonication mediated hydrothermal method using pre synthesized zeolite powders as seeds. The zeolite formation was confirmed by X-ray diffraction pattern and FESEM analysis. The scanning electron micrograph of the membrane, suggested the uniformity of the dense structure of the membrane. Single-gas and mixed-gas permeation experiments through membranes were carried out at 25 degrees C using H-2, CO(2)and N(2)single-component gases and mixture of H-2-CO2, H-2-CO2-N-2-CO for simulated blast furnace gas composition. Synthesized Li-aluminosilicate zeolite shows appreciable CO(2)adsorption capacity at liquid nitrogen temperature compared with other reported zeolites. In case of single gas permeation, membrane shows usual pattern of permeation. For mixture gas, separation efficiency of Li-zeolite membrane increased abruptly compared to the other zeolite membranes. The maximum CO2-H-2, CO2-N(2)and CO2-CO separation selectivities were found to be 78, 8.7 and 67.3 respectively, with permeance of H-2, CO(2)and N(2)2.21 x 10(-7), 1.01 x 10(-7)and 0.8 x 10(-7) mol m(-2) s(-1) Pa(-1)at 25 degrees C respectively
Improving visible-light-induced photocatalytic ability of TiO2 through coupling with Bi3O4Cl and carbon dot nanoparticles
No full textThe fabrication of photocatalysts with considerable photocatalytic performance can be the main purpose for the researchers to substitute the traditional wastewater treatment processes. Accordingly, in this work, visible-light-responsive TiO2/Bi3O4Cl/carbon dots (denoted as TO/BOC/CD) photocatalysts were synthesized via simple strategy. Multiple techniques including EIS, photocurrent, XPS, PL, UV-vis DRS, BET, FT-IR, EDX, XRD, HRTEM, and SEM were employed to explore electrochemical, chemical, and physical features of the nanocomposites. The photocatalytic ability of the samples for Cr (VI), methylene blue, fuchsine, and rhodamine B removals was examined to display their widespread capability in removing different pollutants. The optimal photocatalytic performance related to the nanocomposite with 20% of BOC and 1 mL of CD solution (TO/BOC/CD (1 mL) photocatalyst), which was 13.8, 25.9, 14.2, and 52.3-folds as high as the TiO2 and 2.84, 2.26, 2.57, and 5.25-times higher than the TO/BOC (20%) nanocomposite in removals of Cr (VI), methylene blue, fuchsine, and rhodamine B, respectively. The impressive photocatalytic activity of the TO/BOC/CD photocatalysts is ascribed to the betterment of the optical property of the fabricated photocatalysts. With the enhancement CD content, the respective ternary nanocomposites displayed the highest optical absorption in the visible region. The other reasons in improving the photocatalytic activity are related to increased e(-)/h(+) separation capability, and better textural properties. Additionally, trapping experiments demonstrated that the holes and superoxide anion radicals possess a substantial role during the photocatalytic reaction. Thus, this work could promote the potential utilization of TiO2-based photocatalysts for removal of hazardous contaminants under visible light
Enhanced photothermal conversion in nanometric scale MoOx multilayers with Al2O3 passivation layer
No full textAn optically selective stack based on molybdenum oxide nanometric layers (Mo/MoOx/Mo/MoO3/Al2O3) was designed using SCOUT reflectance simulations and fabricated using balanced magnetron sputtering for applications in solar thermal systems. The material properties were experimentally optimised by varying the process parameters namely: target power, gas flow rates, and deposition time. In the stack, the bottommost Mo metal layer is used to improve adhesion, reduce diffusion while acing as an infrared reflector, the MoOx layer of the tandem stack acts as the primary light absorbing layer, and the topmost MoO3 + Al2O3 layers act as antireflection layers. The individual layers of the optical stack exhibited an amorphous structure as confirmed using X-ray diffraction. The existence of lower oxidation states ( + 4, + 5) of molybdenum in the MoOx layer was revealed by X-ray photoelectron spectroscopy. The stack achieved a high absorptance in the solar spectrum region (alpha = 0.969) and a low thermal emissivity in the infrared region (epsilon = 0.15 at 82 degrees C) at optimal process parameters. The oxidation resistance and thermal stability were evaluated by annealing the samples in vacuum up to 500 degrees C
Effect of heat treatment on microstructure, mechanical, corrosion and biocompatibility of Mg-Zn-Zr-Gd-Nd alloy
No full textPure Mg and prealloyed Mg-Gd-Nd-Zr-Zn alloy samples were prepared using powder metallurgy route and further heat treated. The effects of heat treatment on the microstructure, mechanical , corrosion resistance and biocompatibility properties of these samples were investigated. Microstructural analysis showed alpha-Mg matrix with secondary phases like Mg3Gd/Nd, Mg12Gd/Nd and Mg41Nd5 in the Mg alloy. After heat treatment, 250 degrees C for 12 h, both samples showed improvement in the hardness and compressive strength due to rearrangement of the secondary phases and grains. However, the hardness and compressive strength of Mg alloy (54 +/- 5 HV and 239 +/- 23 MPa) was higher than pure Mg, which were further improved with heat treatment (61 +/- 4 HV and 260 +/- 21 MPa). The corrosion potential of Mg alloy was more positive (-1.51V) than pure Mg (-1.61V) signifying its better resistance to corrosion initiation. However, the Mg alloy exhibited higher corrosion current than pure Mg due to galvanic effect of secondary phases. In vitro tissue culture experiments demonstrated good biocompatibility of both samples and therefore present high strength Mg alloy can be better choice as biodegradable implants. (C) 2019 Elsevier B.V. All rights reserved
Noise-like pulse generation around 1.3-mu m based on cascaded Raman scattering
No full textBased on cascaded Raman scattering, near-infrared (NIR) noise-like pulses (NLPs) were successfully demonstrated using a Yb-doped fiber amplifier system. Through a nonlinear fiber amplifier using a germanium-zirconia-silica Yb3+ -doped single mode fiber as a gain fiber, the fourth-order Stokes wave (4th-SW) can be excited to extend the emission peak of approximately 1.2-mu m and a 3-dB bandwidth of approximately 130 nm. To further shift the wavelength more efficiently toward 1.3 mu m, filtered NLPs with an emission peak at 1075 nm were adopted as seeded pulses to excite the fifth-order Stokes wave (5th-SW) because of the better conversion efficiency of stimulated Raman scattering without gain competition with Yb-doped fiber. The generated NIR NLPs were shown to be an excellent light source for the photoluminescence emission from three photon absorption of perovskite to illustrate the red shift of the emission peak owing to the reabsorption effect. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
Structure and thermal stability of cellulose nanocrystal/polysulfone nanocomposites
No full textThe thermal stability of nanocomposites of cellulose nanocrystals (CNC) dispersed in polysulfone (PSf) was studied to understand the influence of heating rate and CNC concentration using thermogravimetric analysis (TGA). While heating rate was found to have a positive influence on the degradation onset temperature and the maximum degradation rate (Tmax) of these nanocomposites. The influence of CNC concentration appeared to be relatively low on these parameters. PSf/CNC nanocomposites with up to 2 wt.% CNC were found to follow first order degradation kinetics and at higher concentrations, better fit was seen with second-order degradation kinetics. The activation energy associated with nanocomposites degradation, determined using Kissinger method, revealed strong stabilizing effect of PSf matrix on CNC filler. FTIR analysis showed signature peak shifts that correlated with PSf/CNC interactions. On the other hand, the CNC filler had marginal influence on the stability of PSf matrix. Master decomposition curve (MDC) and weight-time-temperature plots were constructed from the obtained activation energies to describe the time-temperature dependence of the PSf/CNC nanocomposite pyrolysis
Novel layered GO/Mg(OH)(2) nanocomposites for detection of Cd and Pb ions
No full textHere we report the efficacy of the photoluminescence (PL) spectroscopy for novel detection of as low as 0.0001 to as high as 0.01 ppm of Cd2+ and Pb2+ ions in simulated wastewater solution. The solution comprises of 20 mg of layered graphene oxide (GO)-Mg(OH)(2) nanocomposite (LGOMHNC) powders in 100 ml of DI water. The LGOMHNC powders, synthesized by facile wet chemical route, are characterized by XRD, FESEM, TEM, FTIR, Raman spectroscopy, TGA-DTA, XPS and especially, the PL spectroscopy techniques. After adsorption of Cd2+ and Pb2+ ions, the novel LGOMHNC powders exhibit significant enhancement of the corresponding PL intensities as compared to those of the as-synthesized LGOMHNC powders. These results suggest that PL spectroscopy can indeed emerge as a very important tool for detection of even 0.0001 ppm of Cd2+ and Pb2+ ions in simulated wastewater. In addition, the novel LGOMHNC powders developed in the present work can have huge application potential in futuristic, optical sensor-based detection of the toxic, heavy metal ions like Cd2+ and Pb2+. (C) 2019 Elsevier B.V. All rights reserved