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Investigations on the laboratory-formulated fritless silver thick film metallisation for use at microwave frequencies is reported here. The reflectometer method has been used to measure the microwave (8-18 GHz) transmittance and... more
Investigations on the laboratory-formulated fritless silver thick film metallisation for use at microwave frequencies is reported here. The reflectometer method has been used to measure the microwave (8-18 GHz) transmittance and reflectance of these films deposited by screen printing onto 96% alumina substrates. The effects of firing temperature, composition and long term air exposure on the microwave properties and d.c. resistivity are also reported. In the X-band frequency, composition and firing temperature-dependent transmittance and reflectance of metallisation are obtained whereas at Kuband, the above properties are to a large extent independent of these factors. The microwave conductivity as well as the d.c. resistivity are found to increase on aging. The results indicate the utility of these fritless Ag thick film metallisation up to 18 GHz. Firing temperature-independent properties provide substantial energy saving and increased furnace life as the films fired at 800°C comp...
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Synthesis of cobalt oxide nanostructures using a facile route still remains a challenge. Herein, we propose a simple, economical and ‘green’ route for the synthesis of cobalt oxide nanostructures by using a two step microwave assisted... more
Synthesis of cobalt oxide nanostructures using a facile route still remains a challenge. Herein, we propose a simple, economical and ‘green’ route for the synthesis of cobalt oxide nanostructures by using a two step microwave assisted solvothermal route. Binary solvent system of water and ethylene glycol (EG) was used as a medium for solvothermal heating in a household microwave oven. We studied the effect of change of microwave power on the morphological properties of the resultant nanostructures. The physico‐chemical investigations reveal formation of nanostructures having faceted growth with different shapes. These nanostructures might prove useful for catalytic and gas sensor applications.
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ABSTRACT In this study, one dimensional Cu doped CdS with higher aspect ratio was synthesized by solvothermal technique. The Cu doping concentration was varied from 0.1 to 5 mol% (CuxCd1−xS where x = 0.001, 0.005, 0.01 and 0.05). The... more
ABSTRACT In this study, one dimensional Cu doped CdS with higher aspect ratio was synthesized by solvothermal technique. The Cu doping concentration was varied from 0.1 to 5 mol% (CuxCd1−xS where x = 0.001, 0.005, 0.01 and 0.05). The prepared compositions were characterized using various spectroscopic techniques such as, UV-visible and photoluminescence, X-ray diffraction, Field emission scanning electron and Transmission electron microscopy. X-ray diffractogram shows formation of crystalline CdS with hexagonal wurtzite structure. The DRS exhibits absorption edge between 520 to 530 nm revealing the band gap of 2.38 to 2.34 eV. Photoluminescence spectrum yielded two distinct peaks at ∼515 and 602 nm. The broad emission band around ∼515 nm corresponds to the band edge excitation. FE-SEM micrographs demonstrate the formation of nanorods with 30–50 nm diameter and 0.5 to 10 �m length. The aspect ratio of CuxCd1−xS nanorods increased with increase in copper doping up to 1 mol%. TEM confirms the formation of crystalline nano rods of Cu doped CdS materials. The photocatalytic activity of the prepared Cu doped CdS was investigated for methylene blue degradation. Among the prepared compositions, Cu0.01Cd0.99S exhibits higher rate of degradation, rate constant observed is 1.42×10−2 min−1. KEYWORDS: Solvothermal Synthesis, 1D Nano Structures, Photocatalysis, Dye Degradation.
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ABSTRACT Synthesis of micron size ZnO rods were synthesized using hydrothermal reaction technique at 200 �C. The synthesized product was systematically characterized with various spectroscopic techniques. XRD analysis revealed the... more
ABSTRACT Synthesis of micron size ZnO rods were synthesized using hydrothermal reaction technique at 200 �C. The synthesized product was systematically characterized with various spectroscopic techniques. XRD analysis revealed the formation of crystalline hexagonal ZnO structure. Photoluminescence spectra exhibited single emission peak at 390 nm corresponds to the band edge excitation, additional peak in the visible region does not exist indicating formation of defect free ZnO material. FE-SEM analysis showed formation of hexagonal shaped rod like morphology with pointed tip. The observed lengths of the rods are in the range of 2 to 10 �m and diameter 0.1 to 0.7 �m respectively. Photocatalytic activity of the prepared ZnO rods was evaluated using methylene blue degradation. The observed rate constant for photocatalytic MB degradation was (kaap) 1.15×10−2 min−1. KEYWORDS: ZnO Rods, Hydrothermal, Photocatalysis, Dye Degradation.
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The NTC powder materials were prepared chemically using acetates of (Mn–Co–Ni), as precursor materials. The sintering of the powders shows the existence of spinel phases at comparatively low temperature, i.e. 800°C. ‘Green’ thick films... more
The NTC powder materials were prepared chemically using acetates of (Mn–Co–Ni), as precursor materials. The sintering of the powders shows the existence of spinel phases at comparatively low temperature, i.e. 800°C. ‘Green’ thick films were prepared by admixing of the spinel powder, RuO2, lead free glass frit and the organic vehicle. Synthesized powders as well as the thermistor films were
Research Interests: Materials Science, Sintering, Microstructure, FTIR spectroscopy, Mathematical Sciences, and 14 moreDielectric Spectroscopy, Physical sciences, Screen printing, Composite Material, Equivalent Circuit, Impedance, Electrical Properties, Spinel, Microstructures, Low Temperature, Theoretical Model, Thermistor, Electrical Impedance, and frit
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In our current endeavor, 3-dimensional (3D) tungsten oxide (WO3) nanostructures (nanocubes, nanobars and nanobricks) have been swiftly generated via hydrothermal route at 160 °C for 24 h. Physico-chemical characterization of the resultant... more
In our current endeavor, 3-dimensional (3D) tungsten oxide (WO3) nanostructures (nanocubes, nanobars and nanobricks) have been swiftly generated via hydrothermal route at 160 °C for 24 h. Physico-chemical characterization of the resultant powder revealed formation of WO3 nanostructures with predominantly faceted cube, brick and rectangular bar-like morphology. The present study was also aimed at exploring the antimicrobial and anticancer potential of WO3 nanostructures. Antimicrobial activity was tested against different micro-organisms viz., Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Aspergillus fumigatus. The antibacterial and antifungal activity was ascertained against these micro-organisms by measuring the diameter of inhibition zone in agar well diffusion test which revealed that the resultant WO3 nanostructures acted as excellent antibacterial agents against both bacteria and fungi but were more effective against the fungus, A. f...
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We report tunable-morphology oriented facile yet scalable route to synthesize 1D (nanorod) and 2D (nanobelt) MoO3 nanostructures at gram scale using conventional as well as sonochemistry assisted sol–gel technique. The structural,... more
We report tunable-morphology oriented facile yet scalable route to synthesize 1D (nanorod) and 2D (nanobelt) MoO3 nanostructures at gram scale using conventional as well as sonochemistry assisted sol–gel technique. The structural, morphological and optical properties of the samples can be befittingly altered by varying the synthesis protocol. The resultant orthorhombic MoO3 nanomorphs demonstrated efficient and expeditious photocatalytic degradation of the pollutant dye, Methylene Blue (MB). We have observed that appreciable photocatalytic MB dye-degradation can be accomplished within 30 minutes with high rate constants of 0.0786 min−1 and 0.233 min−1 for rod and belt-like MoO3-nanostructures, respectively. The pilot results indicate that the resultant MoO3 nanomorphs can be potentially used as solar light driven industrial photocatalyst material with their intrinsic photostability.
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A novel paper-mediated template technique for the synthesis of N-ZnO nanostructures.
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Five ferrocenyl chalcones with phenolic and pyridyl anchors were prepared and their light harvesting properties explored in dye-sensitized solar cells (DSSCs).
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Three new dppe nickel(ii) dithiophosphates with different counteranions synthesized and decomposed to obtain Ni–S systems with same phase independent of the nature of counteranions and alkyl fragments.
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Over the past decade, flexible and wearable microelectronic devices and systems have gained significant importance. Because portable power source is an essential need of such wearable devices, currently there is considerable research... more
Over the past decade, flexible and wearable microelectronic devices and systems have gained significant importance. Because portable power source is an essential need of such wearable devices, currently there is considerable research emphasis on the development of planar interdigitated micro energy -torage devices by employing diverse precursor materials to obtain functional materials (functional carbon, oxides, etc.) with the desirable set of properties. Herein we report for the first time the use of metal organic framework (MOF) and zeolitic imidazolate framework (ZIF-67) for high-wavelength photothermal laser direct writing of metal-decorated, heteroatom-doped, porous few-layer graphene electrodes for microsupercapacitor application. We argue that the specific attributes of MOF as a precursor and the high-wavelength laser writing approach (which creates extremely high localized and transient temperature (>2500 °C) due to strong absorption by lattice vibrations) are together responsible for the peculiar interesting properties of the carbon material thus synthesized, thereby rendering extremely high cycling stability to the corresponding microsupercapacitor device. Our device exhibits near 100% retention after 200 000 cycles as well as stability under 150° bending.
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Research Interests: Microstructure and TCR
In this paper studies on the lab formulated fritless silver thick film paste with two different binder compositions that have been used to fabricate λ/2 microstrip rejection filter in the X and Ku band are reported. These have been... more
In this paper studies on the lab formulated fritless silver thick film paste with two different binder compositions that have been used to fabricate λ/2 microstrip rejection filter in the X and Ku band are reported. These have been compared with ESL (USA) paste and copper thin film metallization for the same circuit. The thick film circuits were overlayed with TiO2 thick film of different thickness and changes in the characteristics studied. In the X band, the Q of the filter improves with overlay and is also dependent on the Ag paste formulation, whereas in the Ku band there are no thick film paste dependent properties observed due to overlay. Thickness of overlay and metallization paste formulation dependent factors should be taken into consideration during fabrication of high density and multi‐layer microwave integrated circuits.
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ABSTRACT Marigold-like ZnO powder was rapidly synthesized by hydrothermal route and the powder was characterized by absorption spectrum (UV-Vis), photoluminescence (PL), X-ray diffraction (XRD) and field emission scanning microscopy... more
ABSTRACT Marigold-like ZnO powder was rapidly synthesized by hydrothermal route and the powder was characterized by absorption spectrum (UV-Vis), photoluminescence (PL), X-ray diffraction (XRD) and field emission scanning microscopy (FESEM). Uv-Vis shows the blue shift in the ZnO with band gap energy 3.37 eV. The synthesized ZnO powder shows pure single crystalline wurtzite hexagonal system with marigold like morphology having bunches of rods. The marigold-like ZnO powder was successfully studied as the electrode material for dye-sensitized solar cells. The better results of photovoltaic parameters of DSSCs with the short circuit current (J sc) of 4.02 mA/cm2, the open circuit voltage (V oc) of 0.556 V, the fill factor (FF) of 0.67 and the overall energy conversion efficiency (η) of 1.5% were obtained.
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PurposeAims to focus on temperature sensors.Design/methodology/approachNegative temperature co‐efficient thermistor powders of ternary Mn, Co, Ni oxide along with RuO2 synthesized at relatively moderates temperature (1,000°C). Thick film... more
PurposeAims to focus on temperature sensors.Design/methodology/approachNegative temperature co‐efficient thermistor powders of ternary Mn, Co, Ni oxide along with RuO2 synthesized at relatively moderates temperature (1,000°C). Thick film thermistor paste compositions were formulated by mixing the semiconducting oxide powder, glass frit and organic vehicle. The physico‐chemical analysis, viz. X‐ray diffraction, scanning electron microscopy and thermogravimetry and IR spectroscopy were carried out for the synthesized powder and the resultant thick films. The X‐ray analysis of the powders showed the cubic spinel structure. The electrical properties like thermistor constant, sensitivity index and activation energy of the thick film NTC thermistor were determined.FindingsThe room temperature resistance is observed to range from 490 KΩ to 4.13 MΩ with thermistor constant ranging from 3,275 to 3,980 K, in the temperature range of 25‐300°C.Originality/valueDescribes research work on tempera...
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The 6,13-pentacenequinone loaded TiO2 catalyst was successfully synthesized via simple wet-impregnation. The highest apparent rate constant was observed among the prepared catalysts is 5.2 × 10−2 min−1 using a PQ/TiO2 catalyst having 0.2... more
The 6,13-pentacenequinone loaded TiO2 catalyst was successfully synthesized via simple wet-impregnation. The highest apparent rate constant was observed among the prepared catalysts is 5.2 × 10−2 min−1 using a PQ/TiO2 catalyst having 0.2 wt% PQ.
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ABSTRACT Environment friendly thick film NTC thermistors based on spinel-type Semiconducting electroceramics compositions based on oxides of (Mn, Co, Ni) were fabricated on cyclindrical/rod type alumina substrate. Prepared rod type NTC... more
ABSTRACT Environment friendly thick film NTC thermistors based on spinel-type Semiconducting electroceramics compositions based on oxides of (Mn, Co, Ni) were fabricated on cyclindrical/rod type alumina substrate. Prepared rod type NTC thermistors were characterized by X-ray diffraction, and Scanning electron microscopy with energy depressive Xray analysis. Rod thermistor samples showed compact and homogeneous microstructure. The electrical parameters such as device resistance, thermistor constant, ageing, thermal cycling, and humidity testing of the thermistors were determined.
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This paper reports the comparison of two fabrication techniques (viz. thin and thick film) for microstrip broadband filter in the X-band. The effect of bulk Al2O3 overlay (in pellet form and at different positions) on the characteristics... more
This paper reports the comparison of two fabrication techniques (viz. thin and thick film) for microstrip broadband filter in the X-band. The effect of bulk Al2O3 overlay (in pellet form and at different positions) on the characteristics of the broadband filter is also reported in this paper. The characteristics vary with the overlay position and thin film circuits seem to
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Research Interests: Engineering, Materials Science, Technology, Nanoparticle, Transmission Electron Microscopy, and 11 moreMedicine, Metal Nanoparticles, Silver, Plasma, Antimicrobial, CHEMICAL SCIENCES, Anti-Bacterial Agents, Bacillus subtilis, Microbial Sensitivity Tests, Silver Nanoparticle, and Nanoscience and nanotechnology
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The rapidly growing wireless industry needs new high performance materials to build low loss, high density, and thermally stable integrated packages. Applications include automotive safety, control, global positioning system (GPS) mapping... more
The rapidly growing wireless industry needs new high performance materials to build low loss, high density, and thermally stable integrated packages. Applications include automotive safety, control, global positioning system (GPS) mapping and entertainment, multifunctional portable phones, video and data transmission through wireless local area network (WLAN) etc. Recently, low temperature co-fired ceramics (LTCC) technology is referred as a key approach
Research Interests: Materials Engineering, Materials Science, Automotive Industry, Dielectric Properties, Ceramic, and 10 moreHigh performance, Conductor, Electrical Properties, Microstructures, High Density Concrete, Wireless Local Area Network, Global position ing system, Data Transmission, High density, and Low loss
There is a need to develop environment friendly electronic materials due to worldwide constraint for the use of hazardous chemicals such as lead, cadmium which are the main constituents of the electronic components. Considering such need,... more
There is a need to develop environment friendly electronic materials due to worldwide constraint for the use of hazardous chemicals such as lead, cadmium which are the main constituents of the electronic components. Considering such need, the work on lead free thick film thermistors has been initiated. Thick film materials have been proved to possess economical processing and functional advantage
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The transmittance and reflectance of microstriplines of different widths, fabricated by thick film and thin film technology are studied in the X and Ku band (8–18 GHz). The fritless thick film Ag pastes with different binder composition... more
The transmittance and reflectance of microstriplines of different widths, fabricated by thick film and thin film technology are studied in the X and Ku band (8–18 GHz). The fritless thick film Ag pastes with different binder composition was formulated indigenously and screen-printed the microstriplines on alumina substrate. These microstriplines were compared with the microstriplines made from ESL (USA) pastes and also Cu thin film circuits. The effect of line width, composition and firing temperature on the thick film microstriplines was investigated. The transmittance of all the indigenously prepared Ag thick film paste compared well with microstriplines prepared with ESL pastes. All these thick film pastes gave good transmittance upto 18.0 GHz. The results indicate firing at 700℃ gives best films, and also 18 mil or 20-mil line width is more suitable than conventional 25-mil line width if thick films are used for metallization upto 18.0 GHz.
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The X-band behaviour of a seven-section parallel-coupled microstrip band pass filter and microstripline due to thin-film Al2O3overlay of different thickness is reported in this paper. This Al2O3film can give a homogeneous overlay... more
The X-band behaviour of a seven-section parallel-coupled microstrip band pass filter and microstripline due to thin-film Al2O3overlay of different thickness is reported in this paper. This Al2O3film can give a homogeneous overlay structure. There is a substantial increase in the bandwidth due to the overlay, the pass band extending towards higher frequency side. In most of the cases, an increase in the pass band transmittance of a microstripline also increases due to a thin-film Al2O3overlay, especially for frequencies less than 9.0 GHz. At higher frequencies, random variations are observed. It is felt that thin-film overlays can be used to modify the microstripline circuit properties, thereby avoiding costly and time consuming elaborate design procedures.
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The long term behaviour of TiO2 thin film overlaid λ/2 L-section rejection filter due to the ageing of the overlay is reported in this paper. The observations are over a period of upto 600 days with exposure to moisture in between. Due to... more
The long term behaviour of TiO2 thin film overlaid λ/2 L-section rejection filter due to the ageing of the overlay is reported in this paper. The observations are over a period of upto 600 days with exposure to moisture in between. Due to overlay, existence of double resonance peaks and shifts in resonance due to the various ageing process is observed. The circuit after 600 days show a considerable shift in the resonance frequency to higher frequency side and increase in Q. The long term ageing aspects of the dielectric layers used for protection, passivation and improvement of circuit properties should be taken into consideration during design and fabrication.