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All-inorganic halide perovskite tuned robust mechanical-energy harvester: Self driven posture monitor and power source for portable electronics
No full textScavenging electric power at ambient from biomechanical movements and mechanical vibrations using piezoelectric nanogenerators (PNGs) has become an accessible energy alternative for the development of self-powered electronic systems and miniaturized power sources for small-scale wearable/portable devices. Here, caesium lead chloride (CsPbCl3)-embedded beta-phase comprising polyvinylidene fluoride (PVDF) hybrid films turns to a suitable functional material for piezoelectric-based mechanical energy harvesters. Incorporation of CsPbCl3 in the PVDF matrix enables high crystallinity and nucleation of electroactive beta-phase similar to 86% in the PVDF with piezoelectric coefficient d(33) of 49 pm/V, much higher as compared to pristine PVDF. Dielectric study as a function of perovskite concentration at room temperature reveals dielectric constant of similar to 66 and low dissipation factor of 0.21 at 1 kHz for optimized hybrid. Saturated ferroelectric P-E hysteresis loop analysis of the synthesized samples indicates variation in remanent polarization with perovskite content. The fabricated PNG delivered instantaneous output voltage of 168 V and peak-to-peak output current of 2 mu A. High sensitivity of the flexible PNGs enables us to measure even a slight deformation due to bending by 2 degrees. Considering its good flexibility and high electrical output performance, optimized PNG was utilized for the fabrication of wearable self-powered posture sensor to monitor regular movement of our spine. Walking based wearable PNGs are also devised for powering up normal android mobile phone batteries. Fatigue test of PNG for continuous 10,000 cycle operation, even after 5 months from the fabrication time, highlights its robustness. Considering such simple and unique amalgamation of polymer and perovskite, these highly flexible PNGs can be easily integrated in portable electronic devices and with the advantage of biomechanical movements as the source of power. (C) 2022 Elsevier Ltd. All rights reserved
Factors governing the sinterability, In vitro dissolution, apatite formation and antibacterial properties in B2O3 incorporated S53P4 based glass powders
No full textIn this report, we have systematically evaluated the role of boron in regulating the degradation, apatite formation and antibacterial properties of bioactive glasses by substituting SiO2 with B2O3 in S53P4 based glass composition. The structural analysis of the glasses has been carried out using neutron diffraction and Raman spectroscopic techniques. The structural analysis of S53P4 base glass has revealed the presence of silicate and phosphate units in the form of Q2Si, Q3Si and isolated Q0P units. With the increasing replacement of SiO2 with B2O3, Raman spectroscopy revealed the formation of non-ring metaborate units and borate rings consisting of both BO3 and BO4 units at the expense of Q2Si and Q3Si units. Furthermore, DSC, HSM and dilatometry results confirmed that the sinterability parameter (Sc) and fragility index (m) values of borosilicate bioactive glasses help in achieving superior sintering and thermal processing without devitrification. Additionally, in vitro SBF immersion studies revealed an accelerated release of Si4+ and Ca2+ ions from the borosilicate glasses. In vitro antibacterial assays against E.coli bacterial inoculum illustrate the critical role of B2O3 in the bioactive glass composition
Enhancing Thermal Sensitivity of Fiber Bragg Grating Sensors Using Conductive Paint
No full textWe propose a temperature sensor based on conductive paint-coated Fiber Bragg Grating (FBG) which can improve the temperature sensitivity of the FBG at 30-300 degrees C. Experimental studies were conducted using conductive carbon paint coatings of various thicknesses on FBG sensors. The coated FBG with average thicknesses of 0.55 mm, 1.35 mm and 2 mm showed significant improvement in the temperature sensitivities of 11.6 pm/degrees C, 17.6 pm/degrees C and 28.1 pm/degrees C respectively in the temperature range of 40-100 degrees C
Generation of stable Q-switched pulses at 1566 nm by using a segment of erbium-doped fiber as saturable absorber
No full textIn this manuscript, the performance of a passively Q-switched fiber laser has been presented, where a segment of un-pumped erbium-doped fiber (EDF) is used as the saturable absorber (SA). We have taken an erbium and ytterbium (Er/Yb) co-doped double cladding fiber as the gain media for efficient pump absorption and checked the potential of the laser by changing the length of the in-house fabricated erbium-doped fiber saturable absorber (EFSA). For a fixed length of EFSA, variation of important system parameters such as output power, repetition rate, pulse width, etc, with the change of the pump power has also been reported. The laser has delivered pulses of a minimum duration of 1.35 mu s with maximum energy of 2.8 mu J. The repetition rate varies in the range from 24.8 kHz to 47 kHz with alteration of the length of the SA. The central wavelength of the output spectra is 1566 nm
Magnesium Aluminate Spinel: Structure, Properties, Synthesis and Applications
No full textMagnesium aluminate (MA) is a spinel group of material and rarely available in nature. It exhibits several advantageous thermal, thermo-mechanical, optical, chemical properties which renders it suitable for wide gamut applications starting from refractory to sensor to IR transmitting window. It has face centered cubic structure and has wide solubility to its end members at elevated temperatures. As a result of this solubility, non-stoichiometric compositions exist in the phase field of spinel in the phase diagram. Due to its unavailability in nature, MA spinels are synthetically prepared through different routes and using different starting materials. Among these, solid state reaction sintering or conventional mixed oxide (CMO) method is the most techno-economical viable process. However, the challenge lies with the preparation of dense MA spinel from its oxide precursors in a single stage process is the expansion due to spinellization. Several attempts have been made to overcome this deterring factor through improving the reactivity of the precursors, by controlling the processing parameters, or by using the mineralizers. In this paper crystal structure, stoichiometry in spinel composition, mechanism of spinel formation, different synthesis method, properties and applications are reviewed
Synthesis of SBA 15 graphene oxide composite membrane using phenol-formaldehyde resin pore modifier for CO2 separation
No full textPresent study highlights the development of carbon-loaded SBA 15 membrane on clay-alumina tubular support and its performance on the CO2 separation efficiencies from different mixture gases. To modify the large pores of SBA 15 by graphitic carbon, low molecular weight phenol-formaldehyde (PF) resin was incorporated into the mesoporous channel followed by calcination under inert atmosphere. The modified ordered pore structure of the membrane has been characterized by low-angle XRD, TEM, and pore size distribution analysis. The chemical state of the deposited carbon phase into the SBA 15 pores was analyzed by X-ray photoelectron and Raman spectroscopy. Carbon having graphitic nature mainly in graphene oxide has been deposited into the mesopore of SBA 15 resulting decrease in pore size from 8.9 to 1.0 nm. Finally, the developed SBA 15 carbon membranes were characterized by CO2 permeation and separation selectivity of CO2/CH4, CO2/CO. Highest CO2/CH4 separation factor was achieved as 16.9 with CO2 permeance 13.6 x 10(-8) mol/m(2)/s/Pa at 200 kPa feed pressure by the 20% resin with 2 times coated membrane. In flue gas analysis, highest CO2/CO separation factor of 32.8 was achieved. This study offers an observation on CO2 separation from simulated BF gas for the first time and the results show the potential of the developed SBA 15/C composite membranes in commercial application
Fabrication of robust ceramic supported polymeric composite nanofiltration membrane for heavy metal contaminated wastewater treatment
No full textNanofiltration (NF) membranes with positive charge are essential for efficient removal of heavy metals and salts from waste water. In this work surface modified positively charged novel `ceramic-supported-polymeric' (CSP) composite NF membranes were fabricated with the copper ions embedded crosslinked polyethyleneimine polymer matrix over tubular ceramic substrate using facile dipcoating method. EDX, ATR-FTIR, XPS, FESEM, AFM and contact angle analyses were performed to characterize the chemical structures and morphologies of the prepared membranes. The composite NF membrane exhibited satisfactory pure water permeability (PWP) of 8.1 L.m(-2).h(-1).bar(-1) and promising salt (87.19 % and 74.41 % for Mg2+ and Ca2+, respectively) and heavy metal ion rejections (91.73 %, 83.15 % and 75.50 % for Zn2+, Ni2+ and Cd2+, respectively). Activation energy and overall size-exclusion-dehydration phenomena along with steric hindrance and Donnan electrostatic exclusion plays an important role for heavy metals and salts rejection. In addition, the membrane showed excellent antifouling properties (>99 % humic acid removal) with high flux recovery ratio (77.6 %) and low flux decline ratio (33 %) for 5 h operations (3rd cycle) together with outstanding antibiofouling ability towards Brevibacillusagri and Leclerciaadecarboxylata. Furthermore, excellent chemical stability of the membrane suggests its potential appli-cation for waste water treatment under critical conditions
A comparative study on copper doped sodium alumina-phosphate glass with conventional and microwave heating
No full textNatural distribution of copper ions CuI] and CuII] in sodium alumina-phosphate glass system under Microwave (MW) heating has been investigated and compared with conventional glass. Higher broad absorption at above 850 nm is observed in glass obtained from resistance heating signifying higher presence of CuII] in conventional glass than that obtained from microwave heating as seen from UV-Vis-NIR spectra. Photoluminescence spectra revel complimentary information on higher presence of CuI] content in MW prepared glass. The peak centre of Cu-2p3/2 as well as Cu-2p1/2 shifted towards higher binding energy and appeared much broader in conventional glass than the glass obtained from MW heating suggesting higher amount of Cu2+ in conventional glass. Moreover, more weight gain in thermo-gravimetric analysis (TGA) suggests higher retention of CuI] in MW melted glass. Raman spectra indicate the P-O non-bridging bond weakening effect upon increasing the copper content; representing the structure modifying role of copper ions on the phosphate network. Fourier Transform Infrared (FT-IR) spectra show the structural features of the phosphate network prepared under two different heating mechanisms. In addition, significant less energy consumption in MW heating makes it energy efficient heating for glass melting
Crystallization kinetics and structural properties of nanocrystalline europium-yttrium-titanate (Eu0.5Y0.5)(2)Ti2O7
No full textWe present a versatile sol-gel approach for nanocrystalline (Eu0.5Y0.5)(2)Ti2O7. We determined the crystallization kinetics of the nucleation and the nucleation mechanism. The crystallization temperature was 1050.1 +/- 0.8 K, and the activation energy of crystallization was 605 kJ mol (-1). The nanocrystal growth started by homogenous nucleation with a constant nucleation rate, and the nanocrystal growth was limited by mass transfer through the phase boundary. The crystal structure of (Eu0.5Y0.5)(2)Ti2O7 was refined from the powder diffraction data using the Rietveld method, and the results were compared with the data recorded for the isostructural compounds, Eu2Ti2O7 and Y2Ti2O7. We proved the existence of a single phase of (Eu0.5Y0.5)(2)Ti2O7 and the regular distribution of Eu3+ and Y3+ ions inside the crystal lattice. The results provide key information regarding the crystallization properties and crystal structure of nanocrystalline (Eu0.5Y0.5)(2)Ti2O7. This knowledge is necessary for preparing pure nanocrystalline powders with tailored structural properties that are suitable for photonic applications. (C) 2022 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved
pH-regulated hydrothermal synthesis and characterization of Sb4O5X2 (X = Br/Cl) and its use for the dye degradation of methyl orange both with and without light illumination
No full textA pH-regulated hydrothermal synthesis method was employed to synthesize Sb4O5Br2 and Sb4O5Cl2 crystallites. Characterization is done by single crystal X-ray diffraction, powder X-ray diffraction, infra-red spectroscopy, scanning electron microscopy and DFT studies. The compounds crystallize in monoclinic symmetry with a P2(1)/c space group. Complete structural analysis of the Sb4O5Br2 compound by using single crystal X-ray diffraction data is performed for the first time and a comparative study with Sb4O5Cl2 is also discussed. The SEM study reveals that the surface morphology changes with the variation of pH for bromide compounds, whereas pH change does not affect the morphology of the chloride analogues. Electronic band structures of the synthesized oxyhalides were investigated in order to understand their catalytic effects in the dye degradation reactions in dark as well as sunlight conditions