IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Assemble of Bi-doped TiO2 onto 2D MoS2: an efficient p-n heterojunction for photocatalytic H-2 generation under visible light
No full textFabrication of noble-metal-free, efficient and stable hybrid photocatalyst is essential to address the rapidly growing energy crisis and environmental pollution. Here, MoS2 has been used as the co-catalyst on Bi-doped TiO2 to form a novel heterostructure to increase the utilization of the photogenerated charge carriers for improving photocatalytic H-2 evolution activity through water reduction. Significantly increased photocatalytic H-2 generation has been achieved on the optimized MoS2/Bi-TiO2 nanocomposite (similar to 512 mu mol g(-1)) after 4 h of visible light illumination, which is nine times higher than that of the pristine TiO2 (similar to 57 mu mol g(-1)). The measurements of photocurrent, charge transfer resistance and photo-stability of MoS2/Bi-TiO2 photoanode imply that charge separation efficiency has been improved in comparison to the pure MoS2 and TiO2 photoanodes. Further, the Mott-Schottky study confirmed that a p-n heterojunction has been formed between n-type MoS2 and p-type Bi-doped TiO2, which provides a potential gradient to increase charge separation and transfer efficiency. On the basis of these experimental results, this enhanced photocatalytic activity of MoS2/Bi-TiO2 heterostructures could be ascribed to the significant visible light absorption and the efficient charge carrier separation. Thus, this work demonstrates the effect of p-n junction for achieving high H-2 evolution activity and photoelectrochemical water oxidation under visible light illumination
Tailoring surface characteristics of bioabsorbable Mg-Zn-Dy alloy using friction stir processing for improved wettability and degradation behavior
No full textMagnesium (Mg) and its alloys are currently under consideration for use as temporary implants. However, early degradation and maintaining mechanical integrity is a significant concern. Surface modification techniques are used to improve mechanical and corrosion properties of Mg based alloys. In the present study, friction stir processing (FSP) was used to tailor the surface characteristics of Mg-1Zn-2Dy (wt.%) alloy for temporary implant applications. The FSPed alloy was characterized using EBSD to understand the influence of FSP on crystallographic texture, grain size and grain boundaries and thereby their effect on corrosion, wettability and hardness. Results showed that the grain size of stir zone (SZ) was refined to less than 3 mm, as a result of dynamic recrystallization (DRX) during FSP and the FSPed alloy exhibited better wettability than as-cast alloy. An increase in the hardness (11.7%) and elastic modulus (6.84%) of FSPed alloy were also observed. Electrochemical corrosion and weight loss methods were conducted in Dulbecco's Modified Eagle's Medium (DMEM) with, 10% Fetal Bovine Serum (FBS) physiological solution. The lower degradation rate (0.72 mm/yr) of FSPed alloy has been attributed to the fine grains and evenly distributed secondary phase particles. Further, the influence of grain boundary characteristics and crystallographic texture on the corrosion behavior have been investigated. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Hydrothermal synthesis of Bi2Fe0O9 nanochains and study of their multiferroic coupling
No full textWe report synthesis of self-assembled Bi2Fe4O9 nanochains by hydrothermal method using Oleic acid as a surfactant which plays an important role in the self-assembled nanochain formation. Temperature dependent dc magnetization study suggests downward shift of the Neel temperature TN -63 K for the particles of size -22 nm while it is reported to be -260 K in the bulk sample. The magnetic hysteresis (M-H) loops offer evidence of weak ferromagnetism across the entire temperature range 10-300 K. Exchange coupling across the interface between coexisting ferromagnetic and antiferromagnetic orders gives rise to a small amount of exchange bias at low temperature. The sample also exhibits substantial magnetoelectric multiferroic coupling at room temperature with-77% suppression of ferroelectric polar-ization under 10 kOe magnetic field. (c) 2021 Elsevier B.V. All rights reserved. Superscript/Subscript Available</commen
The effect of nickel doping on the microstructure and conductivity of Ca(Ti,Al)O3-delta for solid oxide fuel cells
No full textThe ABO(3) type perovskite oxide-based ceramic membranes are one of the most important classes of materials for high-temperature solid oxide fuel cell applications. The acceptor-doped calcium titanate (CaTiO3) perovskite has attracted considerable attention as an oxide ion-conducting membrane due to its potentially high ionic conductivity and excellent stability. Nonetheless, the ionic conductivity of the material must still be improved. Following the strategy of the substitution of dopants on the B-site, the current work is focused on exploring the effect of Al and Ni additions on electrical properties, by studying the nominal compositions CaTi0.7Al0.3-xNixO3-delta (x = 0, 0.1, 0.2 and 0.3). The materials were synthesized by the sol-gel method and studied as a function of phase composition, microstructure, and electrical properties. The results demonstrate an increase of both total and specific grain boundary conductivity with increasing Ni content, while predominant p-type behavior is shown under oxygen-rich atmosphere
Analysis of the Lowest Order Cladding Mode of Long Period Fiber Gratings Near Turn Around Point
No full textA long period fiber grating (LPFG) sensor has been fabricated, after theoretical analysis, obtaining the maximum enhancement of the evanescent field working with the lowest order cladding mode (LP0,2 cladding mode) near turn around point. Both the wavelengths of the dual peak resonance and the coupling conditions of the mode have been analyzed in detail. A flow cell has been fabricated to characterize the sensor in term of surrounding refractive index (SRI) sensitivity. The sensitivity of the sensor resulted to be similar to 8751 nm/SRIU, with a resolution in the order of 10(-5), within the SRI range of 1.333 to 1.3335
Hollow-porous nanospheres of ZnMn2O4 spinel: A high energy density cathode for rechargeable aqueous battery
No full textWell-controlled hollow-porous nanostructures can provide enhanced charge storage capacity owing to the rapid diffusion of electrolyte ions into their interior. However, interface engineering of stable hollow-porous nanostructures with reversible faradaic reactions for efficient energy conversion/storage devices is still a challenge. Herein, we report solvothermal synthesis of spinel ZnMn2O4 with a hollow-porous spherical (ZMOHS) morphology. The formation mechanism of such a hierarchical nanostructure has been discussed. The ZMOHS exhibits a specific capacity of ~187 mAh g−1 at a current density of 2 A g−1 when tested as a faradaic electrode (vs Pt) for a rechargeable aqueous battery (RAB) in alkaline electrolyte. Furthermore, a full cell RAB constituting of ZMOHS//activated carbon (AC) demonstrates energy and power densities of ~215.7 Wh Kg−1 and ~1184.5 W kg−1 respectively, with ultra-long cycling stability (~106% capacitance retention after 10,000 cycles), making it a very promising material for next-generation energy storage device applications
Structure and Stability of High CaO- and P2O5-Containing Silicate and Borosilicate Bioactive Glasses (vol 35, pg 7558, 2019)
No full textEnhanced blue photoluminescence of cobalt-reduced graphene oxide hybrid material and observation of rare plasmonic response by tailoring morphology
No full textCo-RGO nanocomposites are known to show interesting properties suitable for various applications. However, its use in the vital field of plasmonic nanocomposites is restricted as Co nanoparticles have high damping and dielectric loss. In this work, we have demonstrated a simple synthetic way to produce water-dispersible shape variant Co-reduced graphene oxide (RGO) hybrid nanocomposites, which can overcome those barriers and delineate two plasmonic peaks. Prepared multifunctional optical materials show both UV and visible range of plasmonic responses of Co NPs. While the single domain Co NPs show spin-up channel based sharp plasmonic peak in the UV range, the larger particles introduce shape-dependent enhancement of the excitation independent blue photoluminescence of graphene oxide (GO). Usually, due to their different size regime, it is not possible to see both UV and visible range plasmonic responses of Co NPs simultaneously. The variation of the Co particle size was deliberate to achieve multifunctionality. Shape-induced enhancement in the PL spectrum and decoration of plasmonic metal NPs are achieved. TEM micrographs of hybrids confirm the decoration of different shapes of Co nanoparticles on RGO sheets. The size distribution of the nanoparticles in the composites was quantified using two complementary techniques; SAXS/SANS and TEM. Scattering revealed the alteration of RGO agglomeration with the incorporation of differently shaped nanoparticles. Prepared hybrid nanocomposite having both the responses could be promising in magnetoplasmonics, GMR- and doping-based optoelectronics
Directed energy deposition (DED) additive manufacturing: Physical characteristics, defects, challenges and applications
No full textDirected energy deposition (DED) is a branch of additive manufacturing (AM) processes in which a feedstock material in the form of powder or wire is delivered to a substrate on which an energy source such as laser beam, electron beam, or plasma/electric arc is simultaneously focused, thus forming a small melt pool and continuously depositing material, layer by layer. DED has several unique advantages compared to other AM processes, such as site-specific deposition and repair, alloy design, and three-dimensional printing of complex shapes. Herein, recent advances as well as the main aspects governing laser-material interactions during the DED process, melt pool thermal behavior, advanced in situ monitoring, and interaction mechanisms are critically reviewed. The most critical processing variables and their influence on the deposited material properties, along with defect formation mechanisms and characterization techniques, are also identified and discussed. An overview of high-end applications, current challenges associated with DED processing, and a critical outlook of the technology are presented
Role of vanadium oxide on the lithium silicate glass structure and properties
No full textThe structural role of V in 28Li(2)O-72SiO(2) (in mol%) lithium silicate glass doped with 0.5 mol% V2O5 was assessed using Si-29 and V-51 Nuclear Magnetic Resonance (NMR), Fourier-transform infrared (FTIR), and X-ray photoelectron (XPS) spectroscopy techniques. Despite the low amount of V2O5 used, the structural information obtained or deduced from the statistical analysis of the NMR data could explain the evolution of glass properties after V2O5 addition. The XPS results indicated that all vanadium exists in 5+ oxidation state. Both the Si-29 NMR and FTIR data point toward an increase in the polymerization of the silicate network, caused by the V2O5 acting as network former, capable to form various QVn tetrahedral units (for n = 0, 1, and 2) in the glasses. These QVn units, which are similar to phosphate units, scavenge the Li+ ions and cause the silicate network to polymerize. However, in an overall balance, the entire glass network is depolymerized due to the additional nonbridging oxygens contributed by the vanadium polyhedra. The addition of vanadium causes the network to expand and increases the ionic conductivity