IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Surface/Interface Defect Engineering on Charge Carrier Transport toward Broadband (UV-NIR) Photoresponse in the Heterostructure Array of p-Si NWs/ZnO Photodetector
No full textThe surface/interface properties, especially interfacial states, have a key impact on overall carrier generation, recombination/transport, and/or collection proficiency for heterostructurebased photodetectors. This study demonstrates the significant enhancement of ultraviolet-near infrared (UV-NIR) (300-1100 nm) broadband photodetection in the heterostructure array of p-Si NWs/ZnO photodetectors with engineering of surface/interface charge carrier transportation under different processing conditions. In the case of a pulsed laser deposition (PLD)-grown photodetector, coupling of the subsidiary value of the defect state with the interfacial layer (Si-O-Zn) at the p-n junction reduces the charge carrier recombination, resulting in a large enhancement of transient photocurrent in the visible (Vis)-NIR region. However, in the case of a chemical solution deposition (CSD)-grown photodetector, plenty of oxygen vacancies (Vos) become the trap-assisted recombination centers by capturing of photoinduced carriers. The average value of responsivity (R) at 1 V bias for the PLD-grown detector is -5.5 A/W in the Vis-NIR (500-1100 nm) region, whereas in the UV region (<= 375 nm), the value of R reached -8 A/ W. The value of R in the PLD-grown detector is enhanced -102 folds in the UV region and -20 folds in the Vis-NIR region comparison with the CSD-grown detector. Further, carrier generation, trapping, and transport/recombination processes in the surface/interface are well illustrated to explain the dynamics of the charge carrier contributing to the photoresponse behavior in the UV-NIR broadband region
Land Use/Land Cover Change and Environmental Impact Analysis of Ramgarh-Naudiha Region in Uttar Pradesh, India through Geospatial Technology
Full text linkRapidly changing LULC scenario with growing population is of great concern in the modern world. The present study was undertaken to evaluate the changes in LULC pattern in Ramgarh-Naudiha region of Sonbhadra district, UP, over 20 years during 1998-2018 using datasets from the Landsat Thematic Mapper (TM) 5 and Landsat 8 (OLI/TIRS) satellites. LULC map for the chosen period has been generated by unsupervised classification with maximum likelihood algorithm. Results indicate that the study area is vulnerable to such LULC changes due to its sensitive geographic location. It is found that the major changes did happen in agriculture, forest, wasteland and water bodies. Agriculture and Forest areas have decreased by similar to 2 and 6.56% respectively in the study period. The wastelands had increased fast from 5.08% in 1998 to 18.87% in 2018 at the cost of the forest cover and agricultural land respectively. In 1998, water bodies were 7.49%, whereas, it has decreased to 2.04% in 2018. On the contrary, urban fringe area has grown from 0.33% in 1998 to 0.49% in 2018 especially due to population growth. The present study concludes that this LULC analysis will increase awareness and help in taking necessary action in appropriate land use planning and management
A novel composition of bioactive glass with potent haemostatic action and antibacterial competence
No full textHaemorrhagic bleeding is a crucial area of concern related to military as well as civilian trauma. In recent years, bioactive glass is gaining attention in a number of healthcare applications, including haemostasis. Herewith, we report a unique composition of bioactive glass, 70 SiO2: (30-x-y) CaO: x.Al2O3: y.ZnO, where x = 10–18 mole% and y = 0–8 mole%, (Al-BAG) exhibiting haemostatic property as well as antibacterial activity. The as-prepared glass was characterized using XRD, SEM-EDX, FTIR and TG-DSC along with in-vitro degradation study and biological studies e.g., cytocompatibility, haemocompatibility, in-vitro thrombus formation, in-vitro blood absorption capacity, blood coagulation assays (PT, aPTT), in-vitro antibacterial assay against Staph. aureus as well as in-vivo acute dermal toxicity followed by histopathological analysis) and in-vivo haemostasis efficacy were undertaken. The novel bioactive glass composition exhibits promises to be an efficient haemostatic agent with antibacterial activity
Solvothermal Synthesis of Spherical Alumina: Delving into the Formation Mechanism and Morphological Change with Phase Transformation
No full textSpherical shaped mesoporous alumina was synthesized by a simple solvothermal process at 110 degrees C/24 h using aluminum nitrate as precursor in the presence of glycerol, diethyl ether and propanol followed by calcination at 900-1100 degrees C. The transformation of solid spherical gamma-Al2O3 at 900 degrees C into layered shell spherical alpha-Al2O3 at 1000-1100 degrees C was governed by stepwise temperature gradient (Delta T) along the radial direction of interface with adhesion and contraction forces. XRD analysis confirmed the formation of gamma-Al2O3 at 900 degrees C and its conversion to alpha-Al2O3 at 1000 degrees C. The N-2 adsorption-desorption results showed BET surface area and average pore diameter of gamma-Al2O3 as 77.58 m(2) g(-1) and 3.7 nm, respectively. The particle size of alumina spheres was in the range of 1-3 mu m as confirmed by FESEM and TEM studies. The HRTEM images indicated lattice spacing of 0.21 and 0.23 nm corresponding to gamma-Al2O3 with (400) plane and alpha-Al2O3 with (110) plane, respectively. A tentative formation mechanism and the role of glycerol have been explained
Beneficiation of Clays from Ramgarh-Naudiha Region of Sonbhadra District Uttar Pradesh, Impart Improved Properties for Ceramic Industries
No full textChemical and physical properties of clay samples collected from the deposits in the Ramgarh-Naudiha of Sonbhadra district, Uttar Pradesh were examined for their utilisation in ceramic industry. The raw clays from the deposits were found to be siliceous ball clays, contained less kaolinite, non-plastic and were unsuitable for making ceramic items. These clays have been subjected to standard beneficiation techniques which removed the free quartz. The beneficiated clays were less siliceous, had improved properties that can be used as partial replacement material in making ceramic item
Influence of Van der Waals bonds on crystallographic and physical properties of reduced-graphene-oxide/BiFeO3 nanocomposites
No full textWe examined the influence of interfacial Van der Waals vis-a-vis covalent bonds on the crystallographic and physical properties of reduced-graphene-oxide/BiFeO3 nanocomposites. The crystallographic, magnetic, and ferroelectric properties have been measured and it was found that the presence of Van der Waals bonds have rather moderate influence on the structural properties such as distortion, bond lengths and angles, and structural noncentrosymmetry. However, in sharp contrast to the observation made in the case of the nanocomposites containing covalent bonds, presence of Van der Waals bonds results in dramatic decrease in the remanent ferroelectric polarization determined from direct electrical measurements. Van der Waals bonds appear to have changed the characteristics of the BiFeO3-graphene layer interfaces due to either large carrier mobility of the graphene layer and/or generation of strong dead layer. Enhanced functionalities, therefore, could be possible only for covalent bonded oxide-graphene interfaces. (c) 2023 Elsevier B.V. All rights reserved
Effect of stand-off distance on abrasive water jet piercing of ceramic-coated superalloy
No full textThe drilling of film cooling holes on gas turbine blades made out of ceramic-coated superalloy improves the efficiency of the gas turbine and prolongs the life of the turbine blade. The purpose of this study was to investigate the effects of different stand-off distances (SODs) on abrasive water jet (AWJ)-pierced holes, in which the machining time, entry and exit hole diameters, overcut, hole taper, and surface morphology were studied. In this study, the water jet pressure (WJP) of 275 MPa, piercing angle of 90 degrees, dwell time of 0.2 s, and abrasive flow rates (AFRs) of 350 g/min and 400 g/min were considered for the AWJ piercing operations. The entry and exit hole diameters and overcut linearly increased with an increase of SOD with different abrasive flow rates. And hole taper was observed at the coating and substrate sections in which it decreased with an increase of SOD up to 2 mm, and a further increase of SOD increased the hole taper. Besides, the drilled holes were found to have an absence of delamination, cracks, and thermal defects. It was also noted that there is a transformation from a brittle to a ductile mode of erosion that may occur in the high-erosion kinetic energy impact region in the YSZ material section. Based on the experimental results, it is confirmed that SOD of 2 mm became an influencing factor in AWJ for piercing quality holes in the YSZ-coated superalloy
Nano to micrometer range particle size effect on the electrical and piezoelectric energy harvesting performances of hydroxide mediated crosslinked PVDF composites
No full textThe polar phase and piezoelectric response of filler-loaded PVDF-based composites very often depend on the interfacial interaction between the filler surface and PVDF dipoles. In this regard, hydrogen bonding interaction has shown a much stronger effect compared to other interactions. In order to induce hydrogen bonding interaction, the filler surface is commonly modified by various modifiers. In the present work, instead of filler surface modification, we introduce ZnSn(OH)6 filler (hydroxide filler having a high number of -OH groups) into the PVDF matrix in order to facilitate the hydrogen bonding interaction. Not only the hydroxide fillers but the effect of wide particle size variation (from nano to micrometer range) into PVDF has also been shown here for the very first time. ZnSn(OH)6 fillers with similar morphology but different sizes have been synthesized by using a variety of techniques and then incorporated into the PVDF matrix. The microstructural defects of the composite films have been found to be gradually increased with the increase in filler size which in turn caused to gradually increase their space charge polarization. Filler, with 915 nm size has shown the best polar phase formation (-84 %), dielectric permittivity (-10 at 1 kHz), and piezoelectric energy harvesting performance (output voltage -20 V) of the resulting PVDF-based composite and hence has been used for various real-life applications. All of these results have been suitably explained here on the basis of interfacial interaction, microstructural defect, and the mechanism of formation of space charge polarization
Highly efficient tetrametallic PtNiCuCo alloy nanoparticles for sensitive detection of hydrogen peroxide
No full textThe tetrametallic PtNiCuCo alloy nanoparticles were prepared by a simple and cost-effective solution-based approach and spray deposited on fluorine-doped tin oxide (FTO) substrates to use as a highly sensitive catalyst for hydrogen peroxide (H2O2) sensing. The morphological studies revealed that the PtNiCuCo nanoparticles had an average particle size of 5 +/- 1 nm. Electrochemical studies showed that PtNiCuCo nanoparticles possess excellent electro-oxidation activity for hydrogen peroxide at 20 mVs(-1) scanning rate (vs Ag/AgCl). The wide linear range for hydrogen peroxide (H2O2) was obtained from 10 mu M to 16 mM. The detection limits for H2O2 were 0.16 mu M (SNR = 3). The sensitivity of H2O2 was 4367.25 mu AmM-1 cm(-2). These results revealed that the prepared nanoparticles could be a potential candidate for H2O2 sensing
Evaluation of room temperature creep deformation of in situ Fe-based bulk metallic glass nanocomposites by instrumented indentation
No full textIn the present work, Fe57Cr9Mo5B16P7C6 (at. %) in situ bulk metallic glass nanocomposites of varying crystal-linity, i.e. 0 to 80 vol. %, were synthesized by spark plasma sintering. Room temperature indentation creep behaviour of these composites was evaluated with nanoindentation technique. Effect of crystalline phase content on overall creep behaviour of the BMG composites was evaluated. Creep resistance of the BMG composites was improved with increase in the amount of crystalline phases up to 40 vol. %. Improved creep resistance is attributed to the presence of nanocrystalline phases in amorphous matrix and lower defect concentration in the BMG composite samples. However, excess crystallinity imparted brittleness and resulted in poor creep perfor-mance of the BMG composites. Derived stress exponent values are significantly lesser for the BMG composite sample in comparison to the amorphous compact indicating the transition in the mode of plastic deformation from inhomogeneous to nearly homogeneous. Loading rate has more pronounced influence on final creep displacement of fully amorphous sample in comparison to that of BMG composite