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Chemically modified expired Dapsone drug as environmentally benign corrosion inhibitor for mild steel in sulphuric acid useful for industrial pickling process
No full textExpired drug Dapsone was chemically modified by reacting with benzaldehyde; salicylaldehyde and the resulting product (Schiff bases) were investigated as corrosion inhibitor for mild steel in sulphuric acid solution. Schiff base 1 (Dapsone-benzaldehyde) and Schiff base 2 (Dapsone-salicylaldehyde) gave maximum inhibition efficiency of 95.67% and 94.23% at a concentration of 0219 mM respectively. Addition of very small amount of KI (0.602 mM) further increased their efficiency up to 99.03% and 97.98% respectively. The observed results indicate increase in corrosion inhibition efficiency with raising the concentration of the inhibitors. The corrosion inhibition behavior was afforded by the adsorption of Schiff bases onto the mild steel following the Langmuir adsorption isotherm model via mixed physical and chemical adsorption. The synergistic influence of KI at various concentrations of the inhibitors was determined by the calculation of the synergism parameters which suggested a co-operative mechanism. DFT calculations were carried out to elucidate the mechanism of corrosion inhibition process. It was found that the protonated inhibitors are strongly adsorbed on the steel surface than the neutral inhibitors. The results suggest that the developed formulations can be used as corrosion inhibitors during industrial pickling process
Coercivity enhancement and magnetic property evaluation of Bi doped Mn2Sb
No full textMn2Sb is a well-known ferrimagnetic material, which has been investigated thoroughly to understand the effect of doping on its magnetic properties. Present work reports the synthesis of Bi doped Mn2Sb employing arc melting and melt spinning followed by characterization with a view to establish a correlation in the structure and magnetic properties. Bi doping in Mn2Sb lattice produces a significant change in the latter's magnetic properties, giving rise to a saturation magnetization of 27.2 emu/g (27.2 Am-2/Kg) and a high coercivity value of 3.4 kOe (279.2 kA/m), in comparison to Mn2Sb, which has a coercivity of 0.1 kOe (7.96 kA/m). Theoretical studies were carried out to understand the changes in magnetic properties. Ab-initio electronic and atomic structure calculations show that Bi atom occupies equally the MnI and MnII sites and this leads to ferromagnetic ordering, which results in enhancement of the saturation magnetisation. The coercivity mechanism has also been studied in detail; the large coercivity is attributed to the nucleation mechanism achieved via the inclusion of diamagnetic Bi particles in Mn2Sb
Detailed physical property characterization of FeTe1-xSex(0.00 <= x <= 0.50) single crystals
No full textHere, we report self flux single crystal growth of FeTe1-xSex(0.00 <= x <= 0.50) series via solid state reaction route; the resulted crystals as seen are shiny. X-Ray diffraction (XRD) performed on the surface of crystals elucidated the growth in (00l) plane, i.e. orientation in c-direction only. Scanning electron microscopy (SEM) images showed slab like morphology and EDX (Energy dispersive x-ray analyzer) confirmed that the crystals are closed to their designed compositions. Rietveld analysis of the XRD patterns of crushed crystal powders showed that the cell parameters decrease with Se content increase. Coupled magnetic/structural phase transition temperature, seen as a step in resistivity for the lower Se concentration i.e. 0.00 <= x <= 0.07, decreases from around 65 K for x = 0.0 to 50 K for x = 0.07 and it is not detected for higher x values. Superconductivity is observed by resistivity measurement for higher Se concentration i.e. 0.07 <= x <= 0.50, up to a maximum temperature of 14 K at x = 0.50. Thermally Activated Flux Flow (TAFF) analysis based on high field transport measurements in superconducting region done for x = 0.20 crystal exhibited activated flux energy to be decreasing from 12 meV (0.5Tesla) to 4.6 meV (14Tesla). Raman spectroscopy at room temperature of synthesized samples exhibits all the allowed phonon modes with slight shift to higher frequency with Se content. Mossbauer spectra of FeTe1-xSex crystals series were recorded at 300 and 5 K. At 5 K, the average hyperfine field decreases systematically with Se content increase from 10.6 to 6.1Tesla for x = 0.0 to x = 0.20 samples. This indicates a possibility of co-existing magnetism and superconductivity in 0.07 <= x <= 0.20 crystals. For x = 0.50 sample, no hyperfine field related to magnetic ordering is seen. Based on above results, detailed phase diagram of the FeTe1-xSex(0.00 <= x <= 0.50) compounds is defined in the present study
Dielectric and ferroelectric studies of KNN thin film grown by pulsed laser deposition technique
No full textDevelopment of lead-free Potassium Sodium Niobate (or KNN) thin films is significant for the realization of eco-friendly and implantable MEMS based devices. In the present work, KxNa(1-x)NbO3 (x = 0.35) thin films were deposited using Pulsed Laser Deposition (PLD) technique. The effect of deposition parameters on the structure and morphology of KNN thin film has been studied. The electrical, dielectric and ferroelectric properties of KNN thin film in Metal- Insulator- Metal (MIM) capacitor configuration were investigated. The observed dielectric constant (similar to 531) of KNN thin film in the high frequency region (> 500 kHz) was found to be in agreement with the value reported in the literature. Further, the deposited KNN thin film showed ferroelectric behavior with remanent polarization of 8.63 mu C cm(-2)
Electro-oxidation of ethylene glycol on Pt-Co metal synergy for direct ethylene glycol fuel cells: Reduced graphene oxide imparting a notable surface of action
No full textSlow electro-oxidation reaction and low power output are two major limiting factors in successful commercialization of fuel cell technology. An efficient and stable electrocatalyst with effectual metal combination supported on a durable matrix may provide a viable solution to overcome these issues. The direct ethylene glycol fuel cell consisting of bimetallic anode catalysts are expected to lead out the high-power output issues. In the present paper, we emphasized on the synthesis of a high performing CO poisoning resistant Pt based binary anode catalysts for the electro-oxidation of ethylene glycol (EG) using a chemical reduction route. The electrocatalysts consists of Pt-Co alloy nanoparticles with different composition of Pt and Co, supported on reduced graphene oxide (rGO). Physical characterizations revealed the formation of bi-metallic catalysts within the size ranges from 2 nm to 3 nm. Electrochemical analysis revealed that PtxCoy/rGO electrocatalyst with x:y molar ratio of 1:9 imparts the highest peak current and power density as compared to commercially available Pt/C and Pt-Co/C anode catalysts for ethylene glycol electro-oxidation. The power density (81.1 mW/cm(2)) obtained using PtxCoy/rGO with x:y molar ratio of 1:9 metal catalyst in DEGFC is more than other synthesized catalysts at an operating temperature of 100 degrees C and the operating pressure of 1 bar with 2 M ethylene glycol as anode fuel and anode and cathode platinum metal loading of 2 mg/cm(2)
Elucidating the origin of magnetic ordering in ferroelectric BaTiO3-delta thin film via electronic structure modification
No full textWith the motive of unraveling the origin of native vacancy induced magnetization in ferroelectric perovskite oxide systems, here we explore the consequences of electronic structure modification in magnetic ordering of oxygen deficient epitaxial BaTiO3-delta thin films. Our adapted methodology employs state-of-the-art experimental approaches viz. photoemission, photo-absorption spectroscopies, magnetometric measurements duly combined with first principles based theoretical methods within the frame work of density functional theory (DFT and DFT+U) calculations. Oxygen vacancy (O-V) is observed leading partial population of Ti 3d (t(2g)), which induces defect state in electronic structure near the Fermi level and reduces the band gap. The oxygen deficient BaTiO2.75 film reveals Mott-Hubbard insulator characteristic, in contrast to the band gap insulating nature of the stoichiometric BaTiO3. The observed magnetic ordering is attributed to the asymmetric distribution of spin polarized charge density in the vicinity of O-V site, which originates unequal magnetic moment values at first and second nearest neighboring Ti sites, respectively. Hereby, we present an exclusive method for maneuvering the band gap and on-site electron correlation energy with consequences on magnetic properties of BaTiO3-delta system, which can open a gateway for designing novel single phase multiferroic system
Enhanced interfacial properties of graphene oxide incorporated carbon fiber reinforced epoxy nanocomposite: a systematic thermal properties investigation
No full textIn this study influence of the graphene oxide (GO) inclusion on the thermal properties of carbon fiber reinforced polymer (CFRP) hybrid composite is reported. Different wt% content of GO used for development of epoxy matrix and CFRP hybrid composite was prepared using compression moulding process. The nanocomposites were characterized by various techniques viz. DMA, DSC, TMA, and TGA. It is observed that in GO-epoxy resin composites, storage and loss modulus reached maximum for 0.3wt% of GO. The storage modulus of CFRP hybrid composite is achieved almost double with the addition of 0.3wt% of GO. The glass transition temperature (T-g) calculated from DMA and TMA of GO incorporated CFRP hybrid composites demonstrated the enhancement in T-g by 4 degrees C and 12 degrees C respectively over to CFRP composites at 0.3wt% GO. This improvement at GO loading is because of onstraint effect of GO sheets on the polymer chain mobility in the composite
Enhanced Thermoelectric Performance in Hf-Free p-Type (Ti, Zr)CoSb Half-Heusler Alloys
No full textHigh thermal conductivity and exorbitant cost of Hf has for a long time limited the prospects of half-Heusler (HH) alloys for applicability in thermoelectric (TE) energy conversion devices. This work demonstrates the implication of nanostructuring and efficacy of p-type acceptor dopant in (Ti,Zr)CoSb based HH alloys for enhancing the figure of merit (ZT) while eliminating the use of Hf. A series of (Ti,Zr)CoSb1-x(Si,Sn)(x) HH composition was synthesized using arc-melting and consolidated employing spark plasma sintering (SPS). The optimal doping of acceptor dopants, namely, Si and Sn significantly improves the power factor and strengthens the phonon scattering resulting in an enhanced TE performance with maximum ZT of 0.26 and 0.5 at 873 K, obtained for TiCoSb0.8Sn0.2 and ZrCoSb0.8Sn0.2, respectively. For further optimization, microstructural modifications by fine-tuning of the Ti to Zr ratio induces strain field effects and mass fluctuation in (Ti,Zr)CoSb0.8Sn0.2 compositions, which remarkably introduces additional phonon scattering resulting in maximum ZT similar to 0.8 at 873 K for the best performing Zr0.5Ti0.5CoSb0.8Sn0.2 compound. The current study provides a better understanding of p-type dopants in HH materials by which prospective high TE performance can be obtained in low-cost Hf-free p-type (Ti,Zr)CoSb half-Heusler alloys
Evaluation of structural and magnetic property of Cr-doped MnBi permanent magnet material
No full textIn the present study, the effects of doping on the LTP-MnBi phase formation as well as on Mn to Bi ratio in the matrix were investigated. Structural- and magnetic properties of nanocrystalline Mn50-xBi50Crx (x = 0, 1.5, 3, 5) permanent magnet material, prepared by melt-spinning were studied and correlated with the thermal analysis. A more stabilized LTP-MnBi phase is formed with Cr doping. A large enhancement in the coercivity along with magnetization is observed with Cr doping. A magnetization of 54.2 emu/g and a coercivity value of 11.9 kOe were obtained for the composition Mn47Bi50Cr3 at room temperature(,) which increases to 17.5 kOe at 150 degrees C. An interesting correlation exists between the thermal as well as the structural- and magnetic properties of the compound. Also, a decrease in magnetic transition temperature is observed in Cr-doped samples, which has been studied in detail. This decrease in magnetic transition temperature helps in the decoupling of structural- and magnetic transition temperature, thereby leading to a formation of more stable LTP-MnBi compound
Evidence of Slater-type mechanism as origin of insulating state in Sr2IrO4
No full textFor iridates with large spatially extended 5d orbitals, it may be anticipated that distant neighbor interactions would play a crucial role in their ground state properties. From this perspective, we investigate the magnetic structure of Sr2IrO4 by including interactions beyond first and second neighbors, via supercell modeling. Adopting to first-principles scalar relativistic methods, it is found that the minimum in total energy among various magnetic structures correspond to a up arrow up arrow down arrow down arrow type antiferromagnetic ordering of the Ir ions for which the magnitude of the electronic gap, that of the Ir local moments and, the facsimile of the two-peaked structure in the optical conductivity spectra of Sr2IrO4 were found to be in good agreement with the experiments. The results unequivocally show that the origin of the electronic gap in Sr2IrO4 is due to an unconventional antiferromagnetic ordering of Ir ions, thereby classifying the system as a Slater magnet, rather than the spin-orbit coupling driven J(eff) = 1/2 Mott insulator