Research Article
Sangeeta Semwal; Sarab P. Singh; Vasant D. Vankar
Abstract
In present work, hybrid structures of Si Nanocrystals (Si-ncs) and Carbon Nanotubes (CNTs) with bead-like architecture have been synthesized by exposing pristine CNTs to silane (SiH4) at 200 ºC. The exposed CNTs were annealed in Ar ambient at 500ºC in a catalytic chemical vapor deposition chamber. ...
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In present work, hybrid structures of Si Nanocrystals (Si-ncs) and Carbon Nanotubes (CNTs) with bead-like architecture have been synthesized by exposing pristine CNTs to silane (SiH4) at 200 ºC. The exposed CNTs were annealed in Ar ambient at 500ºC in a catalytic chemical vapor deposition chamber. High-resolution transmission electron microscopy (HRTEM) elucidated that the bead-like architecture has well-defined crystalline nature. X-ray photoelectron spectroscopy (XPS) was used to study the nature of chemical bonding and structural functionalization/defects caused by silane exposure and annealing on the nanotube surface. XPS results indicated in-diffusion of Si in the CNT cavity as well reduction in oxygen content on the top surface of the CNTs. X-ray diffractometry was used to further confirm the formation of the crystalline hybrid structures. From the present work it is inferred that a controlled synthesis of hybrid structures (CNT-Si ncs) with bead-like architecture can be achieved by a simple CVD method for various applications
Mahima Khandelwal; Anil Kumar
Abstract
N-doped graphene has been synthesized by the reduction of graphene oxide (GO) using 2-aminoisobutyric acid (AIB) as a reducing agent (N-GrAIB) under mild experimental conditions in aqueous medium. The reduction of GO was indicated by a change in its optical absorption as well as by its Raman spectrum ...
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N-doped graphene has been synthesized by the reduction of graphene oxide (GO) using 2-aminoisobutyric acid (AIB) as a reducing agent (N-GrAIB) under mild experimental conditions in aqueous medium. The reduction of GO was indicated by a change in its optical absorption as well as by its Raman spectrum and 13C solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) studies. The latter two techniques also confirmed the doping of N. N-GrAIB exhibited fairly high conductivity (6.3 S/cm), high specific capacitance (228 F/g at 1 A/g) with good cycling stability for 1000 charge-discharge cycles, high coulombic efficiency (100-101%) and high energy density of 20.26 Wh/kg at a power density of 400 W/kg. The present work shows that this environmental benign N-doped graphene (N-GrAIB) could be a promising electrode material for supercapacitor applications. Copyright © 2016 VBRI Press
Research Article
Mahima Khandelwal; Anil Kumar; Richa Baronia; Shraddha Tiwari; Avanish K. Srivastava; Surinder P. Singh; Sunil K. Singhal
Abstract
In the present work we report a facile method for the synthesis of Pt nanoparticles supported reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) nanocomposite by an in-situ chemical reduction. The incorporation of MWCNTs to rGO leads to decrease in agglomeration between rGO sheets ...
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In the present work we report a facile method for the synthesis of Pt nanoparticles supported reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) nanocomposite by an in-situ chemical reduction. The incorporation of MWCNTs to rGO leads to decrease in agglomeration between rGO sheets due to π – π interactions and higher loading of Pt nanoparticles. In this process, a mixture of exfoliated graphene oxide, CNTs and chloroplatinic acid was treated with a mixture of hydrazine hydrate and ammonium hydroxide at 95° C in an oil bath for 1 h. Pt nanoparticles of 4-6 nm size were homogeneously dispersed on rGO-CNTs nanocomposite as revealed by TEM analysis. Cyclic voltammetry measurements depict an anodic current density of 11.74 mA/cm2 that could be obtained using Pt/rGO-CNTs catalyst and 6.2 mA/cm2 using Pt/rGO catalyst during methanol oxidation, indicating that the catalytic activity of Pt/rGO-CNTs catalyst is almost 2 times higher than that of Pt/rGO catalyst. The electrochemical stability of Pt/rGO-CNTs catalyst was also found to be much higher as compared with that of Pt/rGO catalyst. Thus, Pt/rGO-CNTs catalyst has the potential to be used in the preparation of a promising anode material for direct methanol fuel cell. Copyright © 2016 VBRI Press
Research Article
Pramod Kumar; Rashmi Singh; Faizan Ahmad; Chandra Shekhar; Naresh Kumar; Rachana Kumar
Abstract
A proximity-induced superconductivity is used in a single crystal flake Bi2Te3 topological insulator to probe the behavior of magnetoresistance around the local superconducting critical fields. The magnetoresistance in Bi2Te3 and GaAs materials with superconducting contacts are studied and compared. ...
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A proximity-induced superconductivity is used in a single crystal flake Bi2Te3 topological insulator to probe the behavior of magnetoresistance around the local superconducting critical fields. The magnetoresistance in Bi2Te3 and GaAs materials with superconducting contacts are studied and compared. A contradictory behavior in both of the systems is observed (A positive resistance correction was observed in GaAs, whereas a negative resistance correction was observed in Bi2Te3). For Bi2Te3, periodic oscillations are observed in the dR/d|B| verses B plots. These periodic oscillations originate from a coexistence of proximity-induced superconductivity with a normal linear region created either by temperature or applied magnetic field. At high magnetic fields (> 2T) and low temperatures (1.5K), Shubnikov de Hass oscillations are also observed. Copyright © 2016 VBRI Press
Research Article
Subhadip Chakraborty; Chirantan Das; Anupam Karmakar; Sanatan Chattopadhyay
Abstract
The impedance, capacitance and conductance of aqueous sucrose polar solution are measured by employing impedance spectroscopy method and the current passing through the system for different DC voltages are measured implementing I-V method. The variation of electrical parameters with sucrose content in ...
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The impedance, capacitance and conductance of aqueous sucrose polar solution are measured by employing impedance spectroscopy method and the current passing through the system for different DC voltages are measured implementing I-V method. The variation of electrical parameters with sucrose content in such solution exhibits a quasi-oscillatory nature, which is attributed to the random orientation of water and sucrose dipoles in the solution and their mutual interactions at the molecular level, including water-water, water-sucrose and sucrose-sucrose dipole interactions. To justify the quasi-oscillatory nature from analytical point of view, a theoretical model is developed on the basis of multi-body dipolar interactions of randomly distributed molecular dipoles. The experimental data agrees well with those obtained from the analytical model. The measurement of electrical parameters is performed within a frequency window of 100 Hz to 4 MHz for volume fractions of sucrose with respect to water, ranging from 0.1 to 0.6. The impedance, capacitance and conductance are obtained to be in the range of 0.907 k – 281 k, 38 pF – 266 pF, and 3 µS – 55 µS respectively for the sucrose volume fraction range considered. Current voltage measurements for the same concentration range are performed for a voltage swing between ±5 V and the obtained values vary from +20 µA to -25 µA. The study represents a deterministic approach to analyze the effective nature of a sucrose solution in terms of dielectric polarization of the system which finds application in sucrose quality assessments.
Research Article
Sathosh K. Kurni; Pradip Paik
Abstract
SiO2 nanoparticles of average size 15-20 nm have been synthesized and its dielectric properties have been investigated as a function of frequency (between 20 Hz to 2 MHz). A very high dielectric constant of ca. 14000 at 20 Hz and at room temperature has been observed which is very high compared to the ...
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SiO2 nanoparticles of average size 15-20 nm have been synthesized and its dielectric properties have been investigated as a function of frequency (between 20 Hz to 2 MHz). A very high dielectric constant of ca. 14000 at 20 Hz and at room temperature has been observed which is very high compared to the conventional bulk SiO2 particles (ca. 50-100). For this new SiO2 the loss value is found to be less than 1. These SiO2 nanoparticles with high dielectric constant and low loss can be offered its use in constructing high efficient electronic circuit boards and storage devices. Spectra between real and imaginary parts of dielectric constant reveal an inclined line with depressed semicircle. Impedance measurements have been performed to know the electrical properties of the novel SiO2 nanoparticles. XRD, TEM and FTIR characterizations confirm the solid state network structural, morphological shape and size, and chemical functionality of SiO2 respectively. Copyright © 2016 VBRI Press
Research Article
Rakesh Saroha; Aditya Jain; A. K. Panwar
Abstract
The effects of ZnO nanoparticle coating on the physicochemical and electrochemical properties of LiFePO4 (LFP) have been investigated in this work. ZnO-modified LiFePO4 cathode materials were synthesized via sol-gel and modified by ZnO nanoparticle using ball mill method. The amount of ZnO additive is ...
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The effects of ZnO nanoparticle coating on the physicochemical and electrochemical properties of LiFePO4 (LFP) have been investigated in this work. ZnO-modified LiFePO4 cathode materials were synthesized via sol-gel and modified by ZnO nanoparticle using ball mill method. The amount of ZnO additive is chosen as a controlling factor to tune ZnO content over the surface of LFP particles. Structure and morphology of the LFP material with and without ZnO-coating layer were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectra. The XRD patterns reveal that the proper phase of LFP is formed with the ordered olivine-type orthorhombic structure of Pnma space group, and no impurity phase like LiZnPO4 has been noticed. AC conductivity measurements have shown that the ZnO-modified LFP samples significantly assists in lowering the resistance of cathode active material and enhancing the conductivity. It is found that the 2.5 wt% ZnO-doped LFP exhibits the highest conductivity than the 5 wt% ZnO and 1 wt% ZnO doped LFP or the un-doped sample. Among the synthesized samples, LFPZ2.5 displays highest discharge capacity 160 (±5) mAhg-1 (~94% of the theoretical capacity of LiFePO4) at 0.1C rate. These results indicate that 2.5 wt% ZnO coated pristine LFP sample proves to be alternative material for automotive industry and it may be possible alternate of cathode materials in hybrid electric vehicles. Copyright © 2016 VBRI Press
Research Article
Rozalin Panda; Ramakanta Naik; Udai. P. Singh; Naresh. C. Mishra
Abstract
In the present work, Ag/In/Ag/In multilayers were deposited on glass substrates by DC magnetron sputtering and the films were selenized at 350℃. The selenized films were annealed at 450℃ and 500℃. The selenized and annealed films were characterized by X-ray diffraction (XRD), UV-Visible-NIR spectroscopy ...
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In the present work, Ag/In/Ag/In multilayers were deposited on glass substrates by DC magnetron sputtering and the films were selenized at 350℃. The selenized films were annealed at 450℃ and 500℃. The selenized and annealed films were characterized by X-ray diffraction (XRD), UV-Visible-NIR spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). XRD revealed formation of the desired AgInSe2 phase along with Ag2Se as impurity phase. Unlike in previous studies, where conventional approach of optimizing the volume fraction of initial precursor material is adopted to control the phase purity of AgInSe2, we show that annealing highly impure films at 500℃ can suppress the impurity phase and lead to pure AgInSe2 phase. The suppression of the low band gap Ag2Se impurity phase on annealing the films at 500℃ led to increase in the optical band gap. Copyright © 2016 VBRI Press
Research Article
Mansi Sharma; Deepika Chaudhary; s. Sudhakar; Preetam Singh; K.M.K. Srivatsa; Sushil Kumar
Abstract
The structural investigation of the a-Si:H material, deposited at different pressures by PECVD process, has been carried out to analyze the signatures of diffused intermediate sort of crystalline phases within the amorphous silicon matrix. Raman characterization along with the Photoluminescence ...
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The structural investigation of the a-Si:H material, deposited at different pressures by PECVD process, has been carried out to analyze the signatures of diffused intermediate sort of crystalline phases within the amorphous silicon matrix. Raman characterization along with the Photoluminescence (PL) and spectroscopic ellipsometry studies were carried out to understand the microstructuree of these films. From Raman analysis the material was found to have indistinguishable crystalline phase, which can also be named as “intermediate amorphous phase” (a phase defined between amorphous and ultra nano-crystalline silicon) with crystalline volume fractions as 56 % and 62 % for 0.23 Torr and 0.53 Torr respectively. Here the contribution of ultra nano-crystallites results in higher crystalline fraction, which is not visibly revealed from the Raman spectra due to its sub nano-crystallite characteristics. For the film deposited at 0.53 Torr stable photo-conductance in conjunction with high photo-response under 10 hour light soaking has been observed, which is as expected due to high crystalline volume fraction. The presence of these phases might be the possible reason for the distinct device characteristics though having nearly the similar electrical properties (photo-response ~104). These studies will help to make improvement in the individual layer properties, other than the interface effect, in the fabrication of efficient p-i-n solar cells.
Research Article
Mohan Kumar; Mahima Kaushik; Shrikant Kukreti
Abstract
Electrochemical biosensors (an integrated system of biological constituent and physiochemical detector) have attracted plenty of attention due to its high precision, and importance in clinical diagnosis. In electrochemical biosensors, redox indicators like methylene (MB) blue are used to detect the electrical ...
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Electrochemical biosensors (an integrated system of biological constituent and physiochemical detector) have attracted plenty of attention due to its high precision, and importance in clinical diagnosis. In electrochemical biosensors, redox indicators like methylene (MB) blue are used to detect the electrical changes, which by intercalating between DNA base pairs, can produce an intense redox signal on the surface of ssDNA modified electrode. This study reports the interaction between calf thymus DNA (ctDNA) and new methylene blue (NMB), having almost identical basic skeleton to MB. Various techniques like UV-Visible, thermal melting, fluorescence, circular dichroism (CD) spectroscopy and molecular docking have been utilized. Hypochromism and a red shift in UV-Vis spectra revealed the intercalation binding mode for DNA-NMB complex. Nearly identical binding constants were calculated using UV-Visible and fluorescence spectroscopy. The calculated thermodynamic parameters like change in enthalpy (ΔH°) and entropy (ΔS°) were found to be -6.11×104 and -128.96 JK-1mol-1 at 290 K respectively. CD revealed a change into more compact B-DNA conformation after binding with NMB. These studies suggest that intercalation mode, hydrogen bonding, and van der Waals forces might be responsible for DNA-NMB interaction. This work might further facilitate our understanding about DNA-drug interactions for utilizing them for medicinal purposes and nanochemistry.
Research Article
Aftab H. Mondal; Mohammad T. Siddiqui; Kehkashan Siddiqui; Qazi M. Rizwanul Haque
Abstract
In the present work, biosynthesis of silver nanoparticles (AgNPs) using isolate of Shigella sp. AS8 culture supernatant as a reducing agent has been demonstrated. Synthesis of AgNPs was completed within 180 min of incubation at 35 °C under bright light condition. The biosynthesized nanoparticles ...
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In the present work, biosynthesis of silver nanoparticles (AgNPs) using isolate of Shigella sp. AS8 culture supernatant as a reducing agent has been demonstrated. Synthesis of AgNPs was completed within 180 min of incubation at 35 °C under bright light condition. The biosynthesized nanoparticles were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray (EDX) and Atomic force microscopy (AFM). The formation of brown color reaction product with strong UV-vis spectrum absorption maxima at 411 nm due to surface plasmon resonance (SPR) indicated the synthesis of AgNPs. FTIR spectrum confirmed association of supernatant protein molecules with synthesized nanoparticles. DLS, TEM, FE-SEM and AFM showed biosynthesized nanoparticles were spherical in shape with an average size of 20 nm. EDX data analysis reveals presence of metallic silver. While, XRD analysis revealed that synthesized particles were pure and crystalline in nature. Further, AgNPs were evaluated as an antibacterial agent against extended spectrum β-lactamase (ESBL) positive water-borne pathogens. The results of present study suggest that biosynthesized AgNPs can be used to combat ESBL producing multidrug resistant bacteria.
Research Article
Sagar M. Mane; Sanjay G. Chavan; Pravin M. Tirmali; Dadasaheb J. Salunkhe; Chandrakant B.Kolekar; Shrinivas B. Kulkarni
Abstract
Present paper reports on synthesis and characterization of x[Co0.9Ni0.1Fe2O4]-(1-x)[Ba(Zr0.2Ti0.8)O3] multiferroic magneto-dielectric composite of ferrite and ferroelectric phase for x=0.1, 0.2 and 0.3 via hydroxide co-precipitation method. The well compacted disc shape samples of the MD composites ...
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Present paper reports on synthesis and characterization of x[Co0.9Ni0.1Fe2O4]-(1-x)[Ba(Zr0.2Ti0.8)O3] multiferroic magneto-dielectric composite of ferrite and ferroelectric phase for x=0.1, 0.2 and 0.3 via hydroxide co-precipitation method. The well compacted disc shape samples of the MD composites are sintered with microwave sintering technique at 1100°C. These composites are investigated for their structural, micro-structural, dielectric, ferroelectric and magneto-dielectric properties. X-ray diffraction shows the presence of the peaks corresponding to both ferroelectric and ferrite phases in the composites. Temperature dependent dielectric spectra gives the two anomalies one at lower temperature (below 50°C) corresponds to the ferroelectric transition temperature and other at the higher temperature (above 350°C) corresponding to magnetic transition. The variation of dielectric constant and loss tangent with applied magnetic field between 0-1 tesla in the frequency range of 500 Hz to 1 MHz are investigated. Dielectric constant possesses contribution due to magnetic field dependent interfacial polarization and variations due to the induced stress which can be explained on the observed MD effect.
Research Article
Ashok CH; Venkateswara Rao K; Shilpa Chakra CH
Abstract
Metal oxide nanomaterials shows variety of applications in the field of optoelectronics, semiconductors, catalysis, coatings, solar cells, ceramics, spintronic, biological and sensors. Present paper deals with ZnO/CuO nanocomposite material synthesis, characterization and humidity sensor application. ...
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Metal oxide nanomaterials shows variety of applications in the field of optoelectronics, semiconductors, catalysis, coatings, solar cells, ceramics, spintronic, biological and sensors. Present paper deals with ZnO/CuO nanocomposite material synthesis, characterization and humidity sensor application. Novelty of this work is to know the high sensitivity of two conjugated n and p type semiconductor metal oxide nanocomposite at various temperatures. Nanocomposite materials are synthesized by microwave-assisted method with the help of room temperature ionic liquid (RTIL). Zinc acetate, Copper acetate, Sodium hydroxide and 1-butyl-3-methyl-imidazolium-tetrafluoroborate ([BMIM]BF4) were used as initial precursors. The obtained nanocomposite materials were annealed at different temperatures such as 500 °C, 600 °C, 700 °C and 800 °C. These annealed nanocomposite materials have been characterized by X-ray diffractometer (XRD), Particle size analyzer (PSA), Scanning electron microscope (SEM), Energy dispersive x-ray spectrometer (EDS) and Thermo gravimetric and differential thermal analyzer (TG/DTA) for analyze crystal structure, average particle size, surface morphology, elemental analysis and weight loss respectively. The humidity sensor application was predicted by controlled humidity chamber, hygrometer and digital multi meter. The resistance of the sensing element measured with respect to relative humidity from 10% to 98%. The sensitivity of the nanocomposite material increased from 1.7 % to 2.3 % along with increasing of annealing temperature 500 °C to 800 °C. ZnO/CuO nanocomposite annealed at 800 °C shows high sensitivity means it is also having good response and recovery times.
Research Article
Vinay Sharma; Priyanka Rani; Bijoy K. Kunar
Abstract
Recently, there has been significant interest on the fundamental science and technological applications of complex oxides and multiferroics. Low-power multiferroic have potential to fabricate and characterize frequency tunable, compatible with MMIC Technology, small light-weight for hand-held operation, ...
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Recently, there has been significant interest on the fundamental science and technological applications of complex oxides and multiferroics. Low-power multiferroic have potential to fabricate and characterize frequency tunable, compatible with MMIC Technology, small light-weight for hand-held operation, cost-effective, high-frequency (>10GHz), devices for next generation communication devices and military applications. Multiferroic materials consists of both magnetic and ferroelectric phase and they offer the possibility of magneto-electric (ME) coupling. The purpose of this research is to show strong magnetic field dependent frequency tuning of multiferroics (Nickel doped BFO – BiFe1-xNixO3) based devices over a broad frequency band. We have shown here the magnetic field control of ferromagnetic resonance (FMR) field/frequency from C to Ku band frequencies. Nanoparticles of BiFe1-xNixO3 (x=0.025 & 0.05) were prepared by auto combustion method. The XRD study confirms the formation of pure phase Bismuth Ferrite Nanoparticles. Ferromagnetism of un-doped BFO was enhanced by Ni substitution. Microwave characterization was done in co-planar waveguide (CPW) geometry both in field sweep and frequency sweep mode. BiFe1-xNixO3 nanoparticles were deposited using electrophoretic deposition method (EPD) on top of CPW to do the FMR experiments. The operating frequency of the device was tuned by application of magnetic field (H) over a wide range (5 to 20 GHz) with a field up to 8 kOe.
Research Article
Vinamrita Singh; Vishal Sharma; Swati Arora; Manoj Arora; R. P. Tandon
Abstract
In the present work, the degradation mechanism of ITO/PEDOT:PSS/P3HT:PCBM/Al solar cells has been studied under variable environmental conditions, i.e., in air and under vacuum. It was observed that the absorption for P3HT:PCBM film kept under normal atmospheric conditions decreased slightly after 350 ...
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In the present work, the degradation mechanism of ITO/PEDOT:PSS/P3HT:PCBM/Al solar cells has been studied under variable environmental conditions, i.e., in air and under vacuum. It was observed that the absorption for P3HT:PCBM film kept under normal atmospheric conditions decreased slightly after 350 hours of fabrication. When these films were kept under vacuum, no change in the absorption intensity was observed. However, when the P3HT:PCBM films with PEDOT:PSS layer were studied, an increase in absorption spectra was observed both under air and vacuum. This strongly suggests that the presence of hygroscopic PEDOT:PSS adversely affects the optical properties of thin films and hence the solar cells. The AFM images of the films after degradation showed presence of microscopic holes and mico-sized particles. The decrease in mobilities with time was also less when the devices were kept in vacuum. This suggests that the decrease in mobility is dependent on the decreasing crystallinity of P3HT:PCBM films as observed by XRD data and due to diffusion of impurities. The fall in efficiency of fabricated devices is higher for device exposed to the environment as compared to the fall for device kept under vacuum. These analyses give insight into the possible degradation pathways and help in eradicating the factors responsible for short shelf-life of organic solar cells, thus enabling better device performance in future.
Research Article
Vishal K. Chakradhary; Azizurrahaman Ansari; M.J. Akhtar
Abstract
Material synthesis is a scientific art, considering all parameters and conditions in practical view and applying them in an experiment. Properties of synthesized material can be tuned further by technically playing with concerned parameters individually. In this work, a one to one relation between the ...
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Material synthesis is a scientific art, considering all parameters and conditions in practical view and applying them in an experiment. Properties of synthesized material can be tuned further by technically playing with concerned parameters individually. In this work, a one to one relation between the formation of cubic spinel ferrite structure with stable phase and morphology has been established, and corresponding changes in the magnetic properties are investigated with temperature. Heat treatment method is adopted for the preparation of nanoparticles of cobalt doped nickel ferrite Ni1-xCoxFe2O4 (x=0.5) and characterized by XRD, FESEM, TGA and VSM. Initially, as synthesized powder sample shows amorphous and weak ferromagnetic nature (Ms = 0.04 emu/g, Hc = 92.42 Oe), but heat treatment at 400ºC exhibits signature of phase formation with irregular particle shape and ferromagnetic (Ms = 6.62emu/g, Hc = 460 Oe) behaviour. On further heating upto 600ºC, the nanoparticles of Ni1-xCoxFe2O4 (x=0.5) is formed with stable cubic spinel crystal structure (lattice constant a=8.35452Å) and enhanced magnetic properties (Ms=8.24emu/g, Hc=1955Oe). Due to higher coercivity obtained of Ni1-xCoxFe2O4 (x=0.5) nanoparticles, it may be useful material in the production of data storage devices, permanent magnet, parts of electronic circuits and also in stealth technology.
Research Article
M. Kanakadurga; S. R. Murthy; Arya Das; Rakesh K. Sahoo; Saroj K. Singh
Abstract
ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated ...
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ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated the presence of Zn, O, Na and Cl which confirms the presence of ZnO as major and NaCl as the minor phase. The precipitation of this minor phase after growth and catalytic induction in nano-platelet (NP) morphology during growth has been elucidated. The electrochemical performance of this as-synthesized powder is quite promising. Additionally, the effect of this minor NaCl phase in changing the ionic equilibrium of the electrolyte in capacitance measurement has been analyzed.
Research Article
Hetal Boricha; Zalak Joshi; Davit Dhruv; K.N. Rathod; Keval Gadani; D.D. Pandya; Sanjay Kansara; C.M. Thaker; S. Rayaprol; P.S. Solanki; N.A. Shah
Abstract
In this communication, we report the results of the studies on structural and transport properties of monovalent Na+ doped La1–xNaxMnO3 (LNMO; x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) manganites synthesized by conventional ceramic method. X-ray diffraction (XRD) and Rietveld refinements ...
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In this communication, we report the results of the studies on structural and transport properties of monovalent Na+ doped La1–xNaxMnO3 (LNMO; x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) manganites synthesized by conventional ceramic method. X-ray diffraction (XRD) and Rietveld refinements reveal the single phasic nature of LNMO manganites without any detectable impurity within the measurement range. Temperature dependent resistivity, under different applied magnetic fields, has been performed on LNMO samples. Samples understudy exhibit metal to insulator (semiconductor) transition at temperature TP which is strongly influenced by the substitution of Na+ at La3+ site. r – T plots also exhibit resistivity upturn behavior at low temperature well below 40K under all the applied fields. Variation in TP and resistivity has been discussed in the context of the competition between the transport favoring tolerance factor and zener double exchange (ZDE) mechanism and transport degrading Jahn–Teller (JT) and size variance effects. In order to understand the mechanisms responsible for the charge transport in metallic and semiconducting regions and to explore the possible electronic processes responsible for the observed low temperature resistivity minima in all the presently studied LNMO manganites, various models have been employed. It has been found that VRH mechanism gets successfully fitted to the resistivity data in the semiconducting region while ZDE polynomial law is responsible for the charge conduction in metallic region for all the presently studied LNMO samples. A strong dependence of activation energy on the Na+ – content as well as applied magnetic field has been discussed in the context of variation and interrelations between the structural parameters. Charge conduction in metallic region has been discussed in the light of electron–phonon interactions which is influenced by the Na+ – content and applied magnetic field. Electrostatic blockade model has been employed to understand the low temperature resistivity minima behavior. Blocking energy for the charge carriers shows a dependence on the magnetic energy provided to the charge carriers. Present study can be useful to understand and to control the charge conduction in the manganites and hence to design the manganite based thin film devices for various spintronic applications.
Research Article
Ashok Kumar; Rajiv Borah
Volume 1, Issue 1 , 2016, Pages 146-155
Abstract
Surface modification of polymeric biomaterials for tissue engineering applications has drawn considerable research interest. In this work, the surface of polyaniline (PAni) nanofibers/chitosan nanocomposites has been modified by plasma irradiation technique to improve its biocompatibility. The average ...
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Surface modification of polymeric biomaterials for tissue engineering applications has drawn considerable research interest. In this work, the surface of polyaniline (PAni) nanofibers/chitosan nanocomposites has been modified by plasma irradiation technique to improve its biocompatibility. The average diameter of PAni nanofibers determined by HRTEM is 35.66 nm, whereas FESEM images depict interconnected network of nanofibers dispersed uniformly throughout the chitosan matrix. XRD patterns of PAni/Chitosan nanocomposites after plasma treatment indicate increase in amorphous nature. The alterations in surface morphology after plasma treatment have been confirmed with the help of SEM analysis. The surface chemistry of the samples after plasma treatment has been investigated by means of ATR-FTIR and contact angle measurements. The ATR-FTIR spectra and surface energy measurements show incorporation of polar functional groups after oxygen (O2) and nitrogen (N2) plasma treatment. Preliminary biocompatibility assessments of the plasma treated PAni/Chitosan nanocomposites have been accomplished using Alamar Blue assay with Hep G2 and Primary peripheral blood mononuclear (PBMC) cells. Both assays show maximum enhancement in cell viability for O2 and N2 plasma treated samples, comparing to the pristine one, whereas least cell viability was observed for Ar plasma treated samples. This study depicts that gas plasma treatment can effectively enhance the bioactivity of PAni/Chitosan nanocomposites and can make them attractive for tissue engineering applications.
