Recent Trends in Advanced Materials

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Authors: M. Lakshmipriya, D. Rajan Babu, R. Ezhil Vizhi
Abstract: Single crystal of lithium boro-succinate (LiBS), a semiorganic nonlinear optical material has been grown by slow evaporation method at ambient temperature. The lattice parameter and crystal structure were analysed by powder XRD. The optical transmission spectra revealed optical properties of the grown crystal. FTIR studies confirm the presence of functional group. TGA/DSC studies were carried to find the melting point of the material. Micro hardness has been estimated from LiBS crystal at different forces and various constants were determined by Vickers hardness test.
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Authors: M. Vijayalakshmi, C. Yogambal, D. Rajan Babu, R. Ezhil Vizhi
Abstract: Single Crystal of γ-glycine lithium nitrate with non-linear optical material have been grown by slow evaporation method at room temperature. Structural and Crystalline nature of the grown γ-glycine lithium nitrate crystal was confirmed by powder X-ray diffraction technique. UV-Visible transmittance study was performed to analyze optical transparency of γ-glycine crystal and found that the crystal was transparent in the entire visible region. The mechanical properties of the grown crystal was subjected to Vickers hardness test and the Brittleness index (Bi), Fracture toughness (Kc), Elastic stiffness constant (C11) were estimated.
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Authors: Rajemepu Saravanan, Dodla Rajesh, S. Velu Rajasekaran, Rajakempu Perumal, M. Chitra, Ramaswamy Jayavel
Abstract: Lead free piezoelectric single crystals of sodium potassium niobate (K 0.5Na0.5)NbO3 single crystals were grown by high-temperature solution method using B2O3 flux The KNN crystals grown by without B2O3 flux and with B2O3 flux are referred to as samples A and B respectively. It was found that additions of small amounts of boron oxide B2O3 further lower the melting temperature of the eutectic mixture and exhibits excellent dielectric properties. Phase analysis showed that all samples crystallized in pure orthorhombic perovskite phase. AFM morphological studies show that the root mean square (rms) roughness values were measured to be, 5.3nm and 6.96nm for the sample A and sample B crystal respectively. A slight decrease in the orthorhombic to tetragonal phase transition temperature TOT> and Curie temperature Tc has been observed in sample B when compared with sample A.
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Authors: T. Ramachandran, Nhalil E. Rajeevan, P.P. Pradyumnan
Abstract: Thermoelectricity has gained special interest due to its potential applications, especially the advancements in the electronic devices with very low power consumption. Thermoelectric materials can be used to make energy conversion devices that generate power from thermal sources. Multiferroic oxides, in particular cobaltates, have been actively studied as a new type of thermoelectric material (1). The crystal structure of these cobaltates offers a possibility to manipulate Seebeck coefficient, electric conductivity, and thermal conductivity to optimize the figure of merit ZT. The theoretical explanation and experimental observations by some investigators proved the candidature of multiferroic materials for thermoelectric generation. Many semiconducting multiferroic oxides are showing spin dependent Seebeck coefficient (2-3). Moreover, most of these oxides are inherently stable at high temperatures in air, making them a suitable material for high temperature applications. In this work we have investigated the multiferroic and thermoelectric properties of thinfilms of doped cobalt oxide matrices. The observations confirmed that these materials are suitable for thermoelectric generation.
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Authors: M. Senthilkumar, R. Vijayaraghavan
Abstract: Polycrystalline samples of the Ca3-xNdxCo4-xCuxO9 (x = 0.0 - 0.4) were prepared by the sol-gel cum combustion method using sucrose to investigate the effects of the coupled substitution of Nd and Cu on Ca and Co sites simultaneously on electrical property of Ca3Co4O9 (Co349). The products were characterized by powder x-ray diffraction (XRD), thermogravimetry (TG) / differential thermal analysis (DTA) and scanning electron microscopy (SEM). Powder XRD patterns reveal the formation of single-phase products up to x = 0.4. Coupled substitution increases the solubility of Cu on Co site, in contrast to the limited solubility of Cu (x = 0.3) when separately substituted. TGA confirms the formation of the Ca3Co4O9 phase at around 680 0C. The grain size of the parent and substituted products is in the range of 200-250 nm. Electrical resistivity (ρ) measurement was performed in the temperature range of 300 - 800 K. Electrical resistivity (ρ) of parent sample shows metallic type conduction behavior up to 500 K and above 500 K, it shows semiconducting behavior. All the substituted compositions show semiconducting behavior with increasing electrical resistivity with increasing x. The conduction mechanism was also analyzed. Parent and substituted samples behave thermally activated conduction mechanism in the temperature range of 600 – 800 K.
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Authors: Venkatesan Senthil, Tanmaya Badapanda, Simanchalo Panigrahi
Abstract: Bismuth layered structure SrBi2Ta2O9 ceramic is prepared by the microwave sintering technique via solid state route at 1100°C. X-ray diffraction analysis is used to analyze the phase purity and identifies the orthorhombic phase with A21am space group. The fracture surface morphology of the sintered pellet is visualized by scanning electron microscopy. Diffusive phase transition behavior is existed in the temperature dependence dielectric study at Tc = 305°C. The electrical ac and dc conductivity study shows the negative temperature coefficient of resistance behavior. Activation energy from the Arrhenius plot is studied to discuss the fatigue property.
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Authors: Gomathinayagam Kanthimathi, Pechimuthu Kotteeswaran, Muniasamy Kottaisamy
Abstract: In the present study, the application for the removal of Lead(II) ion from aqueous solution by using synthetic nano Fe3O4 with the average size of 20 nm was investigated by batch method, as a function of concentration, adsorbent dosage, contact time and pH. The equilibrium adsorption isotherm data are tested by applying both Freundlich and Langmuir isotherm models. Macro Fe3O4 was also applied for the removal of Lead(II) ion at the optimum condition of nano Fe3O4 and its efficiency was compared.
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Authors: G. Murali, D. Amaranatha Reddy, B. Poornaprakash, R.P. Vijayalakshmi, N. Madhusudhana Rao
Abstract: Room temperature ferro-magnetism in Fe-doped CdS nanoparticles (NPs) synthesized by a wet chemical precipitation method is reported. Magnetic studies revealed that pure CdS NPs exhibit diamagnetic behavior as like bulk material, where as 3% Fe doped CdS NPs shows the ferromagnetic behavior. At room temperature, ESR signal characteristic of Fe3+ was observed in doped NPs.
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Authors: V. Ranjithkumar, S. Vairam
Abstract: Keywords: Activated carbon; Nanocomposites; Mn3O4; Saturation magnetization Abstract: Activated carbon-Mn3O4 nanocomposites have been prepared by in situ decomposition of metal carboxylates into activated carbon matrix using acetate and benzoate of manganese as precursor for metal oxide. The morphology and size of the Mn3O4 particles inserted into activated carbon matrix have been investigated by IR, XRD, Scanning electron microscope and Transmission electron microscope. The magnetic nature of composites has been investigated by Vibrating Sample Magnetometer.
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Authors: D.S. Jayalakshmi, M. Sundareswari
Abstract: The structural, electronic and magnetic properties of ThCr2Si2-type compounds ARu2Sb2 (A=Sr, Ba) with space group I4/mmm (139) were studied by means of Full Potential – Linearized Augmented Plane Wave Method (FP-LAPW) method by using WIEN2K code. The necessary input parameters to perform the ab-initio calculation for ARu2Sb2 (A=Sr, Ba) are taken from ARu2As2 (A=Sr, Ba). To our knowledge the properties of these compounds have not been investigated before. From this work the optimized structural parameters, bulk modulus, electronic specific heat coefficient, Fermi energy, Magnetic moment are obtained and for ARu2Sb2 (A=Sr, Ba). Density of States histograms and Electron density plots are also plotted to analyze the bonding nature between the atoms in these compounds.
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