IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Effect of dopant oxidation states on enhanced low ppm CO sensing by copper doped zinc oxide
No full textChemiresistive gas sensing by functional ceramics, like semiconductor metal oxides have been so far explained in terms of parameters such as particle size, morphology, temperature, oxygen vacancies, surface charge imbalance and so on. However, the effects of oxidation states of dopants in shaping gas sensing behavior in chemiresistors have been largely ignored. In this work, the role of oxidation states of Cu dopants on improved CO sensing behaviour of ZnO has been categorically analyzed. In this process, a multi-fold enhanced and selective sensing response towards low ppm CO in comparison to pure zinc oxide has been achieved by n-type Cu doped Zinc Oxide. Extensive studies on surface electronic and bulk crystal structures have revealed that relative amount of Cu1+ and Cu2+ is the probable primary cause behind enhanced CO sensing response by Cu doped zinc oxide. Our results thus indicate that by modifying the relative amounts of different oxidation states of dopants, semi-conductor metal oxide systems may be tuned to show improved sensing response towards CO and other gases
In-Vitro Corrosion and Wear Studies of Ceramic Layers on Additively Manufactured Zr Metal for Implant Applications
No full textIn the present study, an attempt has been made to develop in-situ grown ceramic layer on additively manufactured Zr metal by thermal oxidation (TO) treatment. Detailed characterization and testings were performed to determine the thickness of the ceramic layer, oxide phases, hardness, surface roughness, wettability in-vitro wear, and in-vitro corrosion resistance of theses oxidized specimens. The X-ray diffraction analysis confirmed the formation of ZrO2 in the in-situ oxide layer and its thickness increased significantly at higher oxidation temperatures. However, among the samples, lowest in-vitro wear rate (2.12 +/- 0.36 x 10(-6) mm(3)/N m) was demonstrated by the samples oxidized at 600 degrees C for 6 h. Further this obtained wear rate was correleted with thickness of oxide layer, contact angle, surface rougness, and hardness. It is also noticed that the formation of oxide phases on Zr significantly increase the in-vitro corrosion resistance compared to untreated Zr substrate in Hanks Balanced Salt solution (HBSS)
Investigation on porous aluminosilicate soot layer for fabrication of specialty optical fiber using VPCD technique
No full textThe basic investigation of aluminosilicate porous core layer deposited using Vapour Phase Chelate Delivery (VPCD) technique is presented to optimize soot deposition parameters for subsequent processing to develop specialty optical fiber. Different soot deposition parameters namely vapour phase composition and porous core layer deposition temperature were studied in order to evaluate the change of porous soot layer morphology in terms of average pore size, pore size distribution, and chemical composition with the objective of selecting the optimized aluminosilicate soot structure. The field emission scanning electron microscope (FESEM) investigation reveals that the average pore size of the aluminosilicate soot strongly depends on the selected deposition tem-perature and its value increases from 0.7 mu m to 1.8 mu m for increasing deposition temperature from 1150 degrees C to 1250 degrees C. This average pore size of aluminosilicate soot however, increases significantly with addition of dopants like GeO2 and P2O5 and reaches the value of 3.9 mu m and 5.8 mu m respectively. It is also observed that the aluminium deposition efficiency in porous aluminosilicate soot layer depends on selected deposition temperature and for an increase of 20 degrees C, the deposition efficiency of Aluminium in the soot layer increases by-2.7%. It is also observed that aluminium incorporation efficiency using direct VPCD technique reaches a value of-90% compared to 72% if the process carried out by following deposition of porous soot layer. The observed result could help to achieve better control over the VPCD technique and could be extended to fabricate rare earth doped specialty optical fiber of specific design
An insight into the thermal processability of highly bioactive borosilicate glasses through kinetic approach
No full textThe paucity of crystallization resistant bioactive glasses with desired biological functions stands as a bottleneck toward the fabrication of various biomedical constructs such as amorphous coatings, scaffolds, and fibers for advanced tissue engineering applications. In this context, a series of borosilicate-based bioactive glasses with a range of compositions: (53.88 - x)SiO2-21.7Na(2)O-21.7CaO-1.7P(2)O(5)-xB(2)O(3) (mol%) where x = 0, 13.47, 22.45, 31.43, and 40.41 were prepared to address such limitation. The glasses were primarily investigated for their potential to be processed into amorphous scaffolds through evaluation of crystallization kinetics, sintering behavior, and viscosity-temperature dependence. The inclusion of B2O3 gradually reduces the activation energy of crystallization (E-a), according to the prediction from different kinetic models, whereas Friedman's model-free method unraveled the variation in E-a as crystallization progresses. The crystallization event is further elucidated by obtaining the Avrami parameter (n) and dimensionality (m) through Matusita-Sakka equation. The optimization of the sintering schedule for amorphous scaffold preparation was accomplished by exploiting isothermal prediction from Avrami-Erofeev model. Moreover, viscosity-temperature relationship for the studied glasses was established to identify the processing window for drawing and sintering. This study proposes a comprehensive approach adopting theoretical models to elucidate suitable high-temperature process parameters of bioactive glasses avoiding devitrification
Measurement and analysis of pocket milling features in abrasive water jet machining of Ti-6Al-4V alloy (vol 23, 42, 2022)
Full text linkIn-vitro corrosion and biocompatibility properties of heat treated Mg-4Y-2.25Nd-0.5Zr alloy
No full textIn this study, corrosion and biocompatibility behaviour of Mg-4Y-2.25Nd-0.5Zr alloy (Mg-Y-Nd-Zr) was inves-tigated. The pre-alloyed powder of Mg-Y-Nd-Zr was processed using powder metallurgy (PM) method, followed by further heat treatment at 250 degrees C for 12 h. The microstructural features of as-sintered and heat treated Mg-Y-Nd-Zr alloy showed secondary phases like Mg24Y5 and Mg41Nd5 in alpha-Mg matrix. In heat treated samples, the alloy showed improved compressive strength and hardness. The hardness and compressive strength was better for the heat treated Mg-Y-Nd-Zr alloy samples (54 +/- 2 HV and 243 +/- 30 MPa) compared to heat treated pure Mg samples (44 +/- 5 HV and 129 +/- 11 MPa). This is because of rearrangement of the secondary phases in the matrix. The corrosion current density of Mg-Y-Nd-Zr alloy samples reduced by 45% (82.2 mu A/cm2 for heat treated and 149.3 mu A/cm2 for as-sintered) after heat treatment indicating its better corrosion resistance than as-sintered samples. Both heat treated and as-sintered alloy exhibited good biocompatibility and therefore the Mg-Y-Nd-Zr alloy is a potential candidate for biodegradable implants
Fiber grating sensors and their recent applications in biomedical domain
No full textSensors play an important role in measuring various physio-chemical and biological parameters. Biomedical applications of sensors include early level diagnosis of diseases, treatment technique enhancement and also monitoring the effect of medical techniques using suitable biomedical devices. The sensors which are deemed suitable for biomedical applications need to be fast, accurate, flexible, small, and most importantly, biocompatible. The inherent advantages of fibre optic sensors, such as small foot print, electrical passiveness, multiplexing capability and fast response make them the most preferred for biomedical sensing applications. Fibre optics sensors are generally used in the measurement of parameters such as temperature, strain, pressure, displacement, angle, and force. And find applications in diverse regimes like structural health monitoring, shape sensing, seismic sensing; in the bio medical domain, they have been deployed in gait analysis, pulse rate monitoring, body joint angle measurements, acquisition of respiratory parameters, cardiovascular parameters and many more. Despite being a topic of significant interest in biomedical applications, the adoptablility of optical sensors in clinical practice is not very encouraging. Hence, there is a need to address the reasons for the same, and the present review aims to highlight some critical areas. The present review paper primarily discusses the optical fibre grating techniques: their fabrication methods, the applications of these sensors in biophysical and biomechanical measurements, bio proteins and biomarker detection in body fluids. The review also discusses the bottlenecks in the clinical application of these sensors. The comparison of the performance of the optical fibre sensors with other sensing techniques is also discussed in this review paper
Building a ``trap model'' of glassy dynamics from a local structural predictor of rearrangements
Full text linkHere we introduce a variation of the trap model of supercooled liquids based on softness, a particle-based variable identified by machine learning that quantifies the local structural environment and energy barrier for the particle to rearrange. As in the trap model, we assume that each particle's softness, and hence energy barrier, evolves independently. We show that our model makes qualitatively reasonable predictions of behaviors such as the dependence of fragility on density in a model supercooled liquid. We also show failures of the model, indicating in some cases signs that softness may be missing important information, and in other cases features that may only be explained by correlations neglected in the trap model. Copyright (c) 2023 EPL
Corrigendum to `An efficient wideband hafnia-bismuth erbium co-doped fiber amplifier with flat-gain over 80 nm wavelength span' Optical Fiber Technol.(vol 48,pg 186,2019)
No full textPhosphorus based hybrid materials for green fuel generation
No full textPhosphorene, also referred to as phosphorus-based elemental material (black and red), display unusual electronic-structure characteristics, which can significantly enrich the fields of energy application and possesses huge potential in photocatalysis owing to its bandgap tunability, high optical absorption, large surface area, high charge carrier mobilities, and efficient solar to chemical energy conversion. However, due to chemical instability and the poor visible-light utilization efficiency, individual phosphorus materials cannot promote charge transfer and separation. For designing active photocatalysts, phosphorus-based hybrid materials with effective charge carriers separation at the heterojunction interface has played significant role. In this respect, considerable attempts have been made to fabricate black-red phosphorus heterostructure for photocatalytic applications and solar fuel generation, such as photocatalytic and electrocatalysis water splitting, CO2 reduction, carbohydrates synthesis, etc. This review article highlights the strategies for the synthesis of black-red phosphorus heterostructure materials for catalysis with a special focus on their potential for solar fuel generation applications. Recently developed black-red phosphorus heterostructure will be discussed, which can improve the most challenging drawback of phosphorus materials. Finally, the major challenges along with future trends of black-red phosphorus heterostructure in catalytic applications are outlined. This article is categorized under: Sustainable Energy > Solar Energy Emerging Technologies > Materials Emerging Technologies > Hydrogen and Fuel Cell