Abstract

Nanoparticles of Ba_1-x(Al_xCu_xFe_12-x)O₁₉ (x varies from 0 to 1) were prepared by solid-state reaction route method. The structural and morphological characterization of samples has been investigated by X-ray diffraction and TEM. Electron Spin Resonance (ESR), Mossbauer, VSM techniques were used to study the magnetic properties of the compounds. Change in the magnetic state of nanoparticles due to doping was also examined. Mossbauer studies suggest that the sample is ferrimagnetic when x equals 0 and completely paramagnetic when x euqals 1. ESR studies reveal splitting of resonance lines at certain concentrations (x) of Cu/Al. VSM and ESR studies reveal the destruction of collective magnetism when doping is increased.

Keywords

Doped barium ferrite; Eelectron spin resonance; Mossbauer spectroscopy; Magnetic properties

How to Cite

Citation Information: T. Ravindra Reddy, P. Narayana Reddy, S. Lakshmi Reddy, Yoshinobu Nakamura, Satoru Kaneko, Paolo Mele, Taras Polek, Tamio Endo, Magnetic and Resonance Study of Double doped M-type hexaferrite Ba_1-x(Cu_xAl_xFe_12-x)O₁₉, Frontier Research Today, 2019, 2, 2007. doi: 10.31716/frt.201902007

History

Received: 28 August 2019, Accepted: 30 September 2019, Published Online: 02 October 2019

Abstract

The objective of present research work is to investigate the surface morphology, physical and mechanical properties of unidirectional S-glass fiber epoxy composites filled with varying amount of ZnO nanofiller content such as 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt% respectively. ZnO nanofiller was modified with matrix in varying amount using mechanical stirrer and followed by ultrasonication process. The laminate composites were fabricated using a compression molding press technique. Further, laminate composites were subjected to individual characterization and testing in an according to American society for testing and materials standards. The crystalline nature of ZnO nanofiller was studied using X-ray diffraction analysis and surface morphology of ZnO nanofiller on the resin surface was examined by using a scanning electron microscope. The experimental test results revealed that addition of nanofiller content by 1 wt%, 2 wt% and 3 wt% resulted in a gradual reduction of a void fraction by 2.760%, 2.510% and 1.641% respectively and thereafter growth in void fraction increased from 2.696% to 2.833% with 4% and 5 wt% of loading. The flexural and impact strength increased to a maximum of 694.2 MPa and 2550.42 J/m with 3 wt% of loading, with further increasing load content of 4 wt% and 5 wt%, both flexural and impact strength were decreased. Whereas, surface microhardness results showed unique behavior in increased order of 21.6 HV, 24.3 HV, 28.5 HV, 33.7 HV and 38.4 HV with nanofiller loading of 1 wt% to 5 wt%. Thermo-gravimetric test analysis of composites revealed that there was negligible weight loss (%) in composites at 50 ˚C to 380 ˚C. So, composites were thermally stable up to 380 ˚C. Further heating of composites from 380 ˚C to 900 ˚C, the majority of weight loss (%) incurred in composites which were nearly half of the weight loss (%).

Keywords

Nanofiller; Cluster mechanism; Void fraction; Flexural; Impact; Microhardness

How to Cite

Citation Information: Karani Dileep Kumar, Synthesis and prediction of surface morphology, physical and mechanical properties of functionalized nano zinc-oxide embedded in unidirectional S-glass fiber epoxy composites , Frontier Research Today, 2019, 2, 2006. doi: 10.31716/frt.201902006

History

Received: 26 August 2019, Accepted: 23 September 2019, Published Online: 26 September 2019

Abstract

ABSTRACT: The use of Boswellia ovalifoliolata bark extract for the synthesis of zinc oxide nanoparticles (ZnO NPs) with benefits of eco-friendliness, low cost and compatibility for pharmaceutical and biological applications. In this paper, we report the biosynthesis of zinc oxide nanoparticles using plant extract and its application for the detection of picric acid (PA). The synthesized ZnO nanoparticles were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction pattern (XRD), fourier transform infrared spectroscopy (FT-IR) and fluorescene spectroscopy. ZnO NPs in aqueous solution shows maximum absorption bands at 278 nm and fluorescence emission at 317 nm. The fluorescence emission of zinc oxide nanoparticle shows high selectivity towards picric acid (PA) and can be used as a fluorescent probe for the detection of PA via fluorescence quenching mechanism. The fluorescence quenching mechanism of picric acid may be due to the electron transfer process between ZnO NPs and picric acid which is confirmed by cyclic voltammetry (CV). The quenching efficiency of nanoparticle was calculated using Stern-Volmer equation. The limit of detection was found to be 1.83 µM for picric acid. The fluorescence property of the ZnO NPs can be utilized for cell imaging application as biosensors and also in the field of drug delivery.

Keywords

Boswellia ovalifoliolata; Zinc oxide nanoparticle; Picric acid; Nitroaromatic compound;

How to Cite

Citation Information: Geetha Venkatesan, Rajagopalan Vijayaraghavan, Sarada Nallani Chakravarthula, Govindasamy Sathiyan, Fluorescent zinc oxide nanoparticles of Boswellia ovalifoliolata for selective detection of picric acid, Frontier Research Today, 2019, 2, 2002. doi: 10.31716/frt.201902002

History

Received: 29 March 2019, Accepted: 22 April 2019, Published Online: 25 April 2019

Abstract

In this study, the different samples of conducting polyindole (PIn) were synthesized through an oxidative in situ polymerization of pre-adsorbed indole, employing anhydrous ferric chloride (FeCl₃) as oxidant in aqueous solution. The optimized as-synthesized sample was characterized through X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) techniques. The amorphous nature observed in XRD profile delicately supported by FE-SEM picture. The temperature dependent DC electrical conductivities of different as-synthesized samples were measured using two probe technique in the temperature range 303-393 K. The nature of plotted conductivities curves followed Arrhenius relation. The ionic conductivity was found to be dominant over the electronic conductivity and varies between 71% and 83%.

Keywords

Chemical polymerization; Polyindole; DC conductivity; Arrhenius relation

How to Cite

Citation Information: NS Wadatkar, SA Waghuley. Transport studies on one-pot chemically synthesized conducting polyindole in aqueous solution, Frontier Research Today, 2019, 2, 2001. doi: 10.31716/frt.201902001

History

Received: 14 January 2019, Accepted: 28 January 2019, Published Online: 30 January 2019

Abstract

One of the challenges for the non-oxidative coupling of methane (NOCM) is to effectively remove the deposited coke over catalysts owing to the over-dehydrogenation of methane. Herein, we show that an in-situ growth of carbon nanotubes (CNTs) instead of coke were observed during NOCM over a CuSO₄/γ-Al₂O₃ catalyst. The as-grown CNTs depict an unexpected promoting effect for NOCM with a highest activity of 0.48 mol kg cat^-1·h^-1, and maintained 85% activity after 200 h running time. The equilibrium methane conversion is 9.8 % with a selectivity of 78.2 % for C₂ (C₂H₄ + C₂H₆) products. Highly dispersed Cu nanoparticles distributed on the top of CNTs measured by transmission electron microscopy is proposed to result in high catalyst stability during NOCM for 200 h instead of deactivation in several hours. Here, we firstly prove that the as-grown CNTs can promote the catalytic activity of NOCM instead of deactivation by coking over catalysts.

Keywords

Carbon nanotube; Non-oxidative coupling of methane; Copper catalysts; Promoting effect; Catalytic activity

How to Cite

Citation Information: Zhi-Yan Zeng, Jian Chen, Jarrn-Horng Lin, Unexpectedly Promoting Effect of Carbon Nanotubes Grown During the Non-oxidative Coupling of Methane over Copper Catalysts. Frontier Research Today 2018;1:1007. doi: 10.31716/frt.201801007

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History

Received: 20 November 2018, Accepted: 28 December 2018, Published Online: 31 December 2018

Abstract

The electronic properties, bonding structure and magnetic behaviours of oxygen- and chlorine-treated nitrogenated carbon nanotubes (N-CNTs) were studied using x-ray absorption near-edge structure (XANES), scanning photoelectron microscopy (SPEM) and PPMS measurements. The C and N K-edge XANES spectra of chlorine-treated N-CNTs consistently reveal the formation of pyridinelike N-CNTs by the observation of 1s→π*(e_2u) antibonding and 1s→π*(b_2g) bonding states. Features in the C K-edge XANES spectra are shifted by ~0.3 eV toward higher energies and by ~1.1 eV toward lower energies relatively to those of the more symmetrical pyridinelike and graphitelike structured N-CNTs upon chlorination and oxidation, respectively. Increases in N K-edge XANES intensities for both chlorination and oxidation reveal substitution of C–C bonds by C–N bonds consistent with the observed valence-band photoemission spectra of the decrease of the C 2s bond and the increase of the N 2s bond. The valence-band photoemission spectra obtained from SPEM images indicate that chlorination of the nanotubes enhances the C–N bonding. First-principles calculations of the partial densities of states in conjunction with C K-edge XANES data identify the presence of C–Cl bonding in chlorine treated N-CNTs. In the electron field emission of chlorination (N-CNT:Cl) and oxidation (N-CNT:O) of N-CNT shows a high current density (J) of 15.0 mA/cm² has been achieved on chlorination, whereas low J of 0.0052 mA/cm² is observed on oxidation compared to J = 1.3 mA/cm² for untreated N-CNT at an applied electric field E_A of ~1.9 V/mm. The turn-on electric field (E_TO) was ~0.875 and 1.25 V/mm was achieved for N-CNT:Cl and N-CNT:O, respectively, with respect to E_TO = 1.0 V/mm for untreated one. The magnetic behavioural changes occurs when N-CNTs are functionalized with Cl and O respectively.

Keywords

Nitrogenated carbon nanotubes, XANES, Magnetic hysteresis loop

How to Cite

Citation Information: Sekhar Chandra Ray, Nitrogenated Carbon Nanotubes Functionalized with Chlorine and Oxygen: Electronic and magnetic properties for electronic/magnetic device applications , Frontier Research Today, 2018, 1, 1006. doi: 10.31716/frt.201801006

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History

Received: 06 September 2018, Accepted: 27 December 2018, Published Online: 28 December 2018

Abstract

Understanding the criteria warranting the existence, stability, and activity of a given configuration of atoms has pivotal relevance in chemical and materials science. Photocatalysts, traditionally semiconductors, are essential for processes ranging from water purification to water splitting, air filtration, and surgical instrument sterilization, and harvest optical energy to drive chemical reactions. These semiconductors harvest optical energy to drive chemical reactions. With chemical reactions dictated by atomic and molecular interactions at the nanoscale, examining these processes with near-atomic resolution is necessary to understand photochemical processes in depth and to improve materials for next-generation catalysts. The performance and key electronic properties of semiconductors are dictated by the interplay between the surface chemistry and morphology, whose manipulation has inspired experimental and theoretical researchers. This interplay has been clarified by theoretical studies based on atomic-scale modelling with particular attention given to two sets of degrees-of-freedom: the atomic positions and chemical configuration. This perspective article presents the major computational challenges and modern methodological strategies toward advancing the field. The ZnWO₄ material was selected as a case study, and the key concepts developed in recent years are discussed to clarify the morphology, i.e., the exposed surfaces of materials, and explain its functional properties or performance. First-principle calculations capture the geometric and electronic effects on the photocatalytic activity in agreement with experimental data. Indeed, important and often surprising structure-function relations have been observed based in depth atomistic modelling on morphological analysis. An overview of past achievements and future directions is provided according to the authors’ outlook.

Keywords

ZnWO₄; First-principle calculation; Geometric effect; Electronic effect; Photocatalytic activity; Atomistic modelling

How to Cite

Citation Information: F Gouveia A, Assis M, S Cavalcante L, Longo E, Andrés J. Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO₄. Frontier Research Today 2018;1:1005. doi:10.31716/frt.201801005

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History

Received: 14 December 2018, Accepted: 26 December 2018, Published Online: 28 December 2018

Abstract

The present study deals with the synthesis of two structurally different azomethine polyamides and their effect as inhibitor for a steel rebar in chloride containing pore solution. The amorphous and crystalline natures of the polymers were evaluated based on the XRD analysis. Potentiodynamic polarisation and impedance spectroscopy were employed to investigate the inhibition efficiency of the polymers for the protection of the rebar during corrosion. Scanning electron microscopic and atomic force microscopic techniques were used for the surface characterization of the steel in presence of the adsorbed layer formed by the polymer molecule leading to the inhibition from corrosion. The adsorption of the polyamide inhibitors on the steel rebar obeyed Langmuir adsorption isotherm. Two polyamide inhibitors showed similar inhibition efficiency at concentration ranging from 10 to 1000 ppm and maximum efficiency of 99.62% was achieved by the polymer PAMA1. Formation of protective layer on the surface of steel rebar by the inhibitors was attributed to be the reason for corrosion protection under chloride contaminated pore solution.

Keywords

Azomethine Polyamides; Corrosion; Rebar; Electrochemistry

How to Cite

Citation Information: Balasubramaniam B, Selvaraj A, Iyer NR, Ravikumar L, Rai PK, Mondal K, et al. Electrochemical and microstructural analysis of azomethine polyamides as inhibitor for rebar corrosion under chloride contaminated pore solution. Frontier Research Today 2018;1:1004. doi:10.31716/frt.201801004

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History

Received: 04 December 2018, Accepted: 18 December 2018, Published Online: 20 December 2018

Abstract

This article reviews two reasonably novel approaches for remarkable corrosion resistance of metallic material, and discusses challenges and future opportunities. In the first approach, the nanaocrystalline structure of a corrosion resistant alloy has been found to bring about remarkable improvement in oxidation/corrosion resistance of alloys, as a result of the enhancement in diffusivity of the alloying element that is responsible for theformation of a corrosion barrier layer of protective oxide, due to the nanocrystalline structure (vis-à-vis the microcrystalline counterpart of the same alloy). In the second approach, just a monolayer or a few atomic layer thick graphene coating was found to improve corrosion resistance of copper, nickel and copper nickel alloys in aggressive chloride solution by up to two orders of magnitude, because of the unique characteristics of graphene, i.e., impermeability and inertness to aggressive fluids.

Keywords

Nanocrystalline Fe-Cr alloys; Graphene; Corrosion and oxidation resistance

How to Cite

Citation Information: Raman RS. Graphene Coating and Nanocrystalline Alloy Structure: Two Novel Nanotechnology Approaches for Remarkable Corrosion Resistance. Frontier Research Today 2018;1:1003. doi:10.31716/frt.201801003

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History

Received: 30 September 2018, Accepted: 30 October 2018, Published Online: 02 November 2018

Abstract

We report an investigation into the magnetic and electronic properties of partially hydrogen functionalized vertically aligned few layers graphene (FLG) synthesized by microwave plasma enhanced chemical vapor deposition process. The FLG samples are hydrogenated at different substrate temperatures (50^oC - 200^oC) to alter the degree of hydrogenation and their depth profile. The unique morphology of the structure gives rise to a unique geometry in which graphane (full hydrogenation) / graphone (partial hydrogenation) is supported by graphene layers in the bulk, which is very different from other widely studied structures such as one-dimensional nanoribbons. Synchrotron based x-ray absorption fine structure spectroscopy measurements have been used to investigate the electronic structure and the underlying hydrogenation mechanism responsible for the magnetic properties. While ferromagnetic interactions seem to be predominant, the presence of antiferromagnetic interaction was also observed. Free spins available via the conversion of sp² to sp³-hybridized structures and the possibility of unpaired electrons from defects induced upon hydrogenation are thought to be likely mechanisms for the observed ferromagnetic orders. Theoretical point of view different possible reason for the formation of magnetism in Graphene materials also discussed elaborately.

Keywords

Graphene; Graphone; Graphane; XANES; Magnetization; Magnetic hysteresis loop

How to Cite

Citation Information: Ray SC. Electronic and Magnetic Behaviors of Hydrogen Functionalized Graphene Nanostructure Material. Frontier Research Today 2018;1:1002. doi:10.31716/frt.201801002

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History

Received: 08 September 2018, Accepted: 19 September 2018, Published Online: 20 September 2018

Abstract

Functional ligand-protected metal cluster nanomaterials with increased two-photon absorption and two-photon excited emission might result in new technologies within the fields of bio-imaging applications. During this article, I review the two-photon absorption/emission properties of atomically precise ligand-protected silver and gold nanoclusters, coined “ligand-core” NLO-phores. This includes quantum-chemical methodologies using time-dependent density theory. I will analyze physical phenomena and trends resulting in giant two-photon absorption/emission responses of a number of series of model nanoclusters. I will then focus my review on the effects of the relaxation pathways within the linear and nonlinear optical regime, similarly as innovative ways aiming at enhancing their two-photon emission responses.

Keywords

Thiolated gold nanoclusters; Gold; Silver; High-yield synthesis; Mass-spectrometry; Electronic-properties; Optical- properties; Non-linear optics; Multi-photon microscopy

How to Cite

Antoine R. Atomically precise clusters of gold and silver: A new class of nonlinear optical nanomaterials. Frontier Research Today 2018;1:1001. doi:10.31716/frt.201801001

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History

Received: 06 September 2018, Accepted: 12 September 2018, Published Online: 13 September 2018