IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Compatibility study of La2NiO4+delta and La2Mo1.5W0.5O9 as electrode-electrolyte material for solid oxide fuel cell
No full textThe present work investigates the chemical compatibility of La2NiO4+delta (LN) and La2Mo1.5W0.5O9 (W-LMO) as cathode/electrolyte and NiWO4 (NW)/La2Mo2O9 (LMO) as anode/electrolyte material for solid oxide fuel cell (SOFC) application respectively. The x- ray diffraction (XRD) study of LN/W-LMO shows the existence of five phases viz., La2NiO4+delta, La2Mo1.5W0.5O9, NiWO4, NiO and La1.77Mo1.77O8.001. Whereas, the XRD analysis of NW/LMO shows the formation of NiO, higher order molybdates viz., La5Mo4O14 and La12Mo6O35 as a result of partial Mo reduction. The formation of NiWO4 as a secondary phase in La2NiO4+delta/La2Mo1.5W0.5O9 is a potential anode material which is studied with La2Mo2O9 as anode/electrolyte by x-ray photoelectron spectroscopy (XPS). The XPS analysis of NW/LMO in Ar-H-2 atmosphere reveals the partial reduction of Mo to lower oxidation states. The presence of NiWO4 is also verified by Raman spectroscopy with peaks at 698, 778 and 891 cm(-1) with the signatures of W-LMO and Mo-O bonding
Poly aniline (PANI) loaded hierarchical Ti1−xSbxO2 rutile phase nanocubes for selective room temperature detection of benzene vapor
No full textBenzene is one of the aromatic yet hazardous hydrocarbons that are deceptive under their sweet odor. Even in low ppm concentration, benzene vapor in ambient surroundings have been proven to be a major human carcinogen, primarily responsible for leukemia. Often found along with traces of toluene and xylene which have similar molecular structures, selective detection of low concentration benzene, particularly at room temperature is a major challenge. In this work, using the idea that transition from uni-faceted to bi-faceted crystal growth shall induce a change in morphology from spherical to cubical; antimony doped rutile TiO2 nanocubes were synthesized and employed in benzene vapor detection. While the PANI loaded antimony doped (0.03) TiO2 nanocubes showed an enhanced 80% response to 2 ppm benzene in air at room temperature, it was selective (up to 7 times more) against 2 ppm toluene and xylene vapor. The sensors were highly stable against humidity and also reusable for a considerable span of time. The role of specificity in exposed cubical facet has been explained for eliminating cross-sensitivity in benzene detection phenomenon
Efficient energy storage in mustard husk derived porous spherical carbon nanostructures
No full textAn environment-friendly synthesis of highly porous spherical carbon nanostructures (PSCN), in situ doped with N and S, from mustard seed waste has been accomplished. The synthesised PSCN has an interconnected network, abundant active interfaces, heteroatom rich content, and notably high porosity/surface area which are favourable for fast ion transport and efficient charge storage. This active material (PSCN), when employed as lithium-ion battery (LIB) half-cell anode, shows specific charge capacity of 714 mAh g-1 at a current density of 100 mA g-1 even after 550 cycles with 112% capacity retention and high restoration capability. Further, PSCN//LiFePO4 full cell LIB shows an excellent performance with highly reversible capacity of ~195 mAh g-1 at 50 mA g-1 current density for 400 cycles. The PSCN electrode also exhibited 257.8 F g-1 specific capacitance at 0.1 A g-1 current density with ~93% capacity retention after 10,000 cycles, when used as an electrochemical supercapacitor in an aqueous 3M KOH electrolyte. This work provides preparation of high valued and advanced carbon nanostructured material from renewable bio-mass wastes for high-performance electrochemical energy storage application
Unique observations in nanoscale dynamic contact of glass
No full textNanoscale dynamic contact mechanics and prevalent mechanisms of the physics of deformation are important for the applications of glass in mobile phones, car windows, astronomical mirrors etc. However, the same is far from well understood due to the lack of long-range order as glass is an amorphous brittle solid. Therefore, nanotribological experiments are conducted in the ultra-low load range from about 100 to 1000 mu N load and ultra-low speed of 100 mu m.s-1 on soda lime silica (SLS) glass, as a model material. The results provide unique observations on nanoscale wear and friction in glass using SPM technique and their explanations by contact mechanics. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Multifunctional Nanomaterials
Microporous copper chromite thick film based novel and ultrasensitive capacitive humidity sensor
No full textIn this paper we report to have developed a microporous Copper Chromite (CuCr2O4) thick film based capacitive humidity sensor that exhibits excellent response in the range of 1%-98% RH at room temperature. CuCr2O4 spinel nanopowder was synthesized by a facile sol-gel technique. The as prepared CuCr2O4 nanopowder was screen printed to develop a thick film and it was sandwiched between two parallel electrodes of silver and copper to develop a parallel plate capacitive sensor. The CuCr2O4 nanoparticles and the thick film were well characterized by XRD, XPS, FTIR spectroscopy, Raman Spectroscopy, FESEM, TEM, EDX, and contact angle measurement. Various electrical parameters of the sensor, viz. Capacitance (Cp), Dissipation (D), Conductance (Gp), Susceptance (Bp), and admittance (Y) were measured at different frequencies ranging from 100 Hz to 1 MHz. It was observed that the optimum operating frequency is 1 kHz. At this frequency the sensor exhibited very high sensitivity, especially in the low %RH range of 1%-40% (similar to 640 pF change in capacitance), low dissipation loss (<2 for all %RH range), and fast response (similar to 3.6 s) and recovery times (128 s). Further, the sensor exhibits long-term stability (at least 6 months). The sensor may find commercial applications in food packaging, tea industry, hospitals, power plants etc. (C) 2020 Elsevier B.V. All rights reserved
Closed form solutions of convection-diffusion mechanisms in two dimensions for H-2 separation from (H-2/CO2) mixture at room temperature
No full textStudies pertinent to the hydrogen based clean energy systems have seen a significant surge in this decade in order to meet the ever-increasing demand for energy in an environmentally sustainable way. In order to harness hydrogen from available sources, development and characterization of zeolite membranes with high hydrogen selectivity is of pivotal importance. In this study, a sonication based hydrothermal technique is used for the synthesis of DecaDodecasil-rhombohedral (DDR) zeolite membrane. Permeation tests of single gas and mixture of gases were conducted by using an in-house designed permeation cell. For the single gas permeation test, permeate flux was calculated using soap bubble flow meter under varying feed pressure (98-392 kPa) at 303 K. For the mixed gas permeation test, separation selectivity was measured by using gas chromatography. A mathematical model was developed in order to predict the total volume flux of hydrogen. A simple, two-dimensional parameter model was developed to simulate the steady state permeate flux, permeate and retentate streams, and the permeate concentrations for both H2 and CO2. Fourier transform was found to give the best prediction for the axial diffusion coefficient, as well as the concentration distribution of both the components, (H2 and CO2). A good agreement was found between the observed and the calculated values for total volumetric permeate flux (J(V)).The deviation between experimentally obtained results with the predicted values based on the analytical model was found to be as low as +/- 7%, ensuring adequate reliability of the proposed analytical model
New insight into the growth of monolayer MoS2 flakes using an indigenously developed CVD setup: a study on shape evolution and spectroscopy
No full textMonolayer MoS2 has received special consideration owing to its intriguing properties and its potential to revolutionize modern technologies. Atmospheric pressure chemical vapor deposition (APCVD) is the traditional method to grow uniform and high-quality MoS2 flakes in a controlled manner. Little is known, however, about their synthesis mechanism and shape evolution. Herein, we report the synthesis of monolayer MoS2 flakes at atmospheric pressure using a home-built CVD setup. A wide range of shapes are grown from triangular shapes to many point stars, via in-between shapes such as four and six-point stars, using the weight ratio variation of MoO3 and S precursors at different growth temperatures. Further, the properties of the as-grown MoS2 flakes are probed by optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Raman spectroscopy, photoluminescence (PL), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS), confirming that they are regular and good in quality. Moreover, the synthesis pathway and different shape formations are explained on the basis of the fluid model and the growing rate of Mo, S zigzag edges. Thus, this work provides a better insight into the synthesis mechanism of monolayer MoS2 and represents a significant step towards realizing potential future applications
Microstructure and properties of parts manufactured by directed energy deposition of water-atomized low-alloy steel powders
No full textThe feasibility of using water-atomized low-alloy steel powders Fe-0.11C-0.59Mn-0.43Si-0.45Cu-0.3Cr-0.45Ni0.15Mo-0.05 V (wt.%)] for additive manufacturing using a laser-based directed energy deposition (DED) process was evaluated. Different processing parameter combinations were assessed to arrive at optimum parameters to fabricate different sample geometries, which were characterized in terms of microstructures and mechanical properties. Selected samples were also evaluated after homogenization at 1075 ?C for 10 min. The results show that DED of water-atomized low-alloy steel powders is possible, yielding unique non-directional and refined microstructures with fine spherical oxide particles dispersed throughout the matrix. The maximum tensile strength and total elongation achieved in the as-built condition were 315 MPa and 3.4%, respectively, which improved to 350 MPa and 10.3% after heat treatment. The presence of a sizeable fraction of oxide nanoparticles, which presumably originated from the oxide layer of the water-atomized powder, enabled retention of microhardness/strength after heat treatment despite grain coarsening. However, the porosity and loss of C and Mn were found to be the major concerns with water-atomized powder. We believe that inconsistent powder flow due to the irregular morphology of the powders is the primary cause of the porosity. On the other hand, the high laser absorptivity of the powders due to their rough surface texture and surface oxides could be responsible for the loss of alloying elements due to excessive powder and/or melt pool temperatures. Although the results of our study are quite encouraging, powder characteristics like size and/or morphology need to be further optimized to exploit the full potential of this additive manufacturing methodology
Role of calcium phosphate and bioactive glass coating on in vivo bone healing of new Mg-Zn-Ca implant
Get PDFPresent investigation focuses on development and detailed characterization of a new Mg alloy sample (BM) with and without coating of hydroxyapatite (BMH) and bioactive glass (BMG) by air plasma spray method. After detailed mechano-physico-chemical characterization of powders and coated samples, electrochemical corrosion and SBF immersion tests were carried out. Detailed in vitro characterizations for cell viability were undertaken using MG-63 cell line followed by in vivo tests in rabbit model for studying bone healing up to 60 days. Starting current density increases from BM to BMH to BMG indicating highest resistance towards corrosion in case of BMG samples, however BMH also showed highest i(corr) value suggesting slowest rate of corrosion than BM and BMG samples. Dissolution of calcium ion in case of BMH and BMG control formation of apatite phases on surface. Ca2+ ions of coatings and from SBF solution underwent reduction reaction simultaneously with conversion of Mg to MgCl2 releasing OH- in the solution, which increases pH. Viability and propagation of human osteoblast-like cells was verified using confocal microscopy observations and from expression of bone specific genes. Alkaline phosphatase assay and ARS staining indicate cell proliferation and production of neo-osseous tissue matrix. In vivo, based on histology of heart, kidney and liver, and immune response of IL-2, IL-6 and TNF alpha, all the materials show no adverse effects in body system. The bone creation was observed to be more for BMH. Although both BMH and BMG show rays of possibilities in early new bone formation and tough bone-implant bonding at interface as compared to bare Mg alloy, however, BMG showed better well-sprayed coating covering on substrate and resistance against corrosion prior implanting in vivo. Also, better apatite formation on this sample makes it more favourable implant. GRAPHICS]
Zr+4-controlled nucleation and microstructure in Si-Mg-Al-K-B-F glass-ceramic sealant (solid oxide fuel cell)
No full textThis work illustrates the strong effects of Ti4+ and Zr4+ (M4+) on nucleation ability of SiO2-MgO-Al2O3-B2O3-K2O-F glass-ceramic sealant. An addition of such 5 wt.% M4+ content caused a slight increase in density value (2.60-2.61 g.cm(-3)). X-ray diffraction (XRD) experiment revealed no indication of any crystallinity in melt-quenched glass-sealant and that was further confirmed from transmission electron microscopy. XRD established the development of multicrystalline phases in investigated glass-sealants at solid oxide fuel cell (SOFC) operation temperature (=800 degrees C). The reflected XRD peaks on the heat treated (i.e., 800 degrees C) SiO2-MgO-Al2O3-B2O3-K2O-F glasses were indexed as norbergite (Mg2SiO4 center dot MgF2), humite Mg7F2(SiO4)(3)], chondrodite Mg5F2(SiO4)(2)], mullite (3Al(2)O(3)center dot 2SiO(2)) and enstatite (MgSiO3) phases. Field-emission scanning electron microscope (FESEM) experiment indicated that the plate-like crystallite particles (size 3-10 mm) were precipitated in a mother glass matrix heated at 800 degrees C and restructured into droplet-type morphology when nucleation was supported by Ti4+ ions. The presence of Zr4+ ion results an interlocked type microstructure that is desirable for sealing application because of their capability to resist the growth of a microcrack caused due to thermal stress. A wide thermal expansion value (=11.06 x 10(-6)/K) compatible with SOFC components (electrode, electrolyte, interconnect, and so on) is achieved for Zr4+-doped SiO2-MgO-Al2O3-B2O3-K2O-F glass-ceramic. No considerable deformation in thermal expansion value up to 10 thermal cycling operations is obtained for Zr4+ doped glass and this is ascribed to the interlocked type morphology (FESEM). (C) 2020 Elsevier Ltd. All rights reserved