IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Enhancement in energy storage and piezoelectric performance of three phase (PZT/MWCNT/PVDF) composite
No full textThe conversion of mechanical energy (vibration) to electrical signal (voltage/power) is one of the versatile phenomena in energy harvesting process. In the effort to develop self-powered devices that will convert readily available vibrations into electrical power and no external source of energy will be required for operation, a three phase hybrid piezoelectric nanogenerator comprising of Lanthanum doped Lead Zirconate Titanate (PLZT), Polyvinyldene fluoride (PVDF) and Multi-walled Carbon Nanotubes (MWCNT) as supplement filler was fabricated. Piezoelectric composite films were prepared using tape casting technique, followed by hotpress. The addition of PLZT to PVDF and further MWCNT in PLZT-PVDF composite resulted in the enhancement of dielectric, ferroelectric, piezoelectric and energy storage properties. A maximum open circuit AC peak-to-peak voltage of 20 V was obtained from the nanogenerator after applying repeated human figure tapping and releasing motion on the sample. After rectification of the output AC voltage by bridge rectifier, the DC voltage was able to charge a 40 mu F commercial capacitor up to 8 V (2 mW power) and during discharging of the capacitor, around 50 LEDs were glowed. A 40 mu F capacitor was also charged by using the same method after applying foot pressure on the nanogenerator which delivered 1.5 mW power with 6 V DC voltage and 250 mu A short circuit current. Thus the amount of power delivered by the fabricated nanogenerator can drive several LEDs and charge capacitor which can be used for powering small electronic devices
Si microline array based highly responsive broadband photodetector fabricated on silicon-on-insulator wafers
No full textWe report a high responsivity broad band photodetector working in the wavelength range of 400-1100 nm made from a horizontal array of Si microlines (line width similar to 1 mu m) fabricated on a silicon-on-insulator (SOI) wafer. The array was made using a combination of plasma etching, wet etching and electron beam lithography. It forms a partially suspended (nearly free) Silicon microstructure on SOI. The array detector under full illumination of the device shows a peak Responsivity of 28 A W-1 at 750 nm, at a bias of 1 V which is more than an order of magnitude of the responsivity in a typical commercial Si detector (<= 1 A W-1). In a broad band of 400-1000 nm the responsivity of the detector is in excess of 10 A W-1. We could isolate the contributions of different parts of the microline to the photocurrent by using focused illumination. It was established through simulation that the partial suspension of the microlines in the array is necessary to obtain such high responsivity. The partial suspension isolates the microlines from the bulk of the wafer and inhibits carrier recombination by the underlying oxide layer leading to enhanced photoresponse which has been validated through simulation
Degradability and in vivo biocompatibility of doped magnesium phosphate bioceramic scaffolds
No full textIn the present study, degradability and in vivo biocompatibility of doped magnesium phosphate (MgP) scaffolds were evaluated. 0.5 wt% Zn, 0.5 wt% Si, and 2 wt% Sr doped MgP scaffolds were prepared with up to 47% porosity. Zn doped MgP scaffolds showed nearly 13% weight loss when immersed in SBF for 8 weeks whereas least degradation was noticed for Sr doped samples. In vitro cytocompatibility study, using MC3T3-E1, showed significantly higher cell proliferation at day 5 in a composition independent manner. When implanted in rabbit femur, micro-CT (mu-CT) results showed extensive degradation for Zn doped MgP scaffolds after 2 months while significant bone growth was noticed for both Si and Sr doped scaffolds. (C) 2019 Elsevier B.V. All rights reserved
New observations and critical assessments of incipient plasticity events and indentation size effect in nanoindentation of ceramic nanocomposites
No full textThe ceramic nanocomposites (CNCs) like zirconia toughened alumina (ZTA) ceramics are important futuristic materials for structural and functional applications in advanced strategic systems, structural components, biomedical prostheses and devices. In all structural materials including the ZTA CNCs, the very early stages of plastic deformation i.e., the incipient plasticity events (IPE) are most important to be understood so that the microstructure and mechanical properties can be tuned to suit a given end application. Here we report for the first time the mechanisms of IPE in the nanoindentation experiments conducted at 10-1000 mN loads in the 40 ZTA CNCs. Here 40 ZTA CNC stands for 40 vol% of 3 mol% Yttria partially stabilized zirconia toughened alumina (40ZTA) CNC. The role of load ranges in variations of the IPE related parameters in the 40 ZTA CNCs is also studied. Further, an attempt is made to assess how the amount of zirconia content in ZTA CNCs affects the variations of the IPE related parameters. Through the extensive usage of field emission scanning electron microscopy (FESEM) and theoretical estimations, efforts are also directed to check out the linkage, if any, between the localized shear deformation and/or microcracking with the IPE events that occur in the present CNCs. In addition, a new concept of damage resistance is introduced for the first time in the present work to explain the presence of a strong indentation size effect (ISE) in the 40 ZTA CNCs. Finally, an attempt is also directed to understand how the indentation load (P) controls the relative size of interaction zones of dislocation loops as well as the damage resistance and thereby, engineer the acuteness of the ISE in ZTA CNCs. The implication of these findings in futuristic design of especially the ZTA CNCs for various applications is also discussed
Citation Convergence of Academic Conference Papers
No full textAcademic conferences are regularly held to disseminate knowledge amongst researchers in various disciplines. Due to mismatch of topics, impact of some papers is constrained. In this work, text mining algorithm has been designed to collate the citations of all papers presented in a conference series. Attempt is made to connect the papers on the basis of journals or conferences they refer to. A small subset of such knowledge repositories is thus found to span all the presented papers. A few papers remain disconnected from the giant component so formed, mainly due to improper out-of-context referencing. One case study covering a flagship international conference observed over six consecutive years is presented to demonstrate the method
Preparation of Bi-Doped ZnO Thin Film over Optical Fiber and Their Application as Detection of Ethylenediamine in an Aqueous Medium Based on the Evanescent Field Technique
No full textSynthesis of pure ZnO and bismuth‐doped ZnO (xBi/Zn) (x = 6 wt%) thin‐film based optical fiber sensor and their material/optical characterization such as Brunauer–Emmett–Teller (BET) analysis, field‐emission scanning electron microscopy (FESEM), and energy dispersive X‐ray (EDX) analysis is reported. As‐prepared material such as xBi/Zn is deposited over the optical fiber, and optimum clad thickness in the range of 2–5 μm is achieved through MATLAB simulation to enhance the feasible evanescent field interaction with gas analyte molecules. The modal field analysis of the sensing probe before and after the deposition of xBi/Zn is also studied using COMSOL Multiphysics Modeling software and find strong light propagation into the LP04 mode. The sensing probes are tested in different chemicals and ethylenediamine (EDA) is found to be the most suitable candidate in the concentration range of 100–800 ppm. The response time of the ZnO and xBi/Zn‐doped thin‐film‐based optical sensor is found to be 20 and 15 s, whereas the corresponding sensitivity (%) is 1.078 and 3.483, respectively. The repeatability test of the sensor is also carried out which reveals good response stability
Policy challenges and opportunities inpost-covid India
No full textThe ongoing crisis of COVID is an unprecedented episode in independent India. It has thereforenecessitated extraordinary measures. Not only have these measures left the country totallyunprepared to come in terms with the consequences, they have also posed unique challengesbefore the policy makers who are tasked with rebuilding the country once the crisis subsides.Expectedly, almost no sector has been left unscathed; each presenting their own set of challenges(and interestingly also opportunities) during the period of recovery. This paper does not makeany empirical or critical analysis; it is a generalized discussion of the challenges andopportunities covering a few chosen areas that have been exposed by the pandemic. The mainobjective is to flag some thoughts on what we could learn from the COVID and what policyoptions could insulate the country from similar threats in future
Probing the Influence of γ‑Sterilization on the Oxidation,Crystallization, Sliding Wear Resistance, and Cytocompatibility of Chemically Modified Graphene-Oxide-Reinforced HDPE/UHMWPEN a nocomposites and Wear Debris
No full textOsteolysis and aseptic loosening due to wear at the articulating interfacesof prosthetic joints are considered to be the key concerns for implant failure in load-bearing orthopedic applications. In an effort to reduce the wear and processingdifficulties of ultrahigh-molecular-weight polyethylene (UHMWPE), our research grouprecently developed high-density polyethylene (HDPE)/UHMWPE nanocompositeswith chemically modified graphene oxide (mGO). Considering the importance ofsterilization, this work explores the influence ofγ-ray dosage of 25 kGy on the clinicallyrelevant performance-limiting properties of these newly developed hybrid nano-composites in vitro. Importantly, this work also probes into the cytotoxic effects of thewear debris of different compositions and sizes on MC3T3 murine osteoblasts andhuman mesenchymal stem cells (hMSCs). In particular,γ-ray-sterilized 1 wt % mGO-reinforced HDPE/UHMWPE nanocomposites exhibit an improvement in the oxidationindex (16%), free energy of immersion (−12.1 mN/m), surface polarity (5.0%), andhardness (42%). Consequently, such enhancements result in better tribological properties, especially coefficient of friction (+13%)and wear resistance, when compared with UHMWPE. A spectrum of analyses using transmission electron microscopy (TEM) and invitro cytocompatibility assessment demonstrate that phagocytosable (0.5−4.5μm) sterilized 1 mGO wear particles, when present inculture media at 5 mg/mL concentration, induce neither significant reduction in MC3T3 murine osteoblast and hMSC growth norcell morphology phenotype, during 24, 48, and 72 h of incubation. Taken together, this study suggests thatγ-ray-sterilized HDPE/UHMWPE/mGO nanocomposites can be utilized as promising articulating surfaces for total joint replacements