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Mohanty B.B.,Betnoti College Betnoti | Sahoo P.S.,Betnoti College Betnoti | Sahoo M.P.K.,RGU IIIT | Choudhary R.N.P.,ITER
Advanced Materials Letters | Year: 2012

The polycrystalline Ba3Sr2GdTi3V7O30 material of tungsten bronze structural family was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis exhibits the formation of single-phase compound with orthorhombic crystal system. Surface micrograph recorded by scanning electron microscopic (SEM) technique has well defined but non-uniformly distributed grains throughout the surface of the pellet sample. Detailed studies of dielectric properties as a function of temperature (306-773 K) and frequencies (102-106Hz) suggest that the compound has frequency independent diffused dielectric anomaly at a temperature ~620 K which may be related to ferroelectric phase transition which is confirmed from polarization study. The frequency and temperature dependence of impedance property of the material were analyzed using a complex impedance spectroscopy. The Nyquist plots confirmed the presence of grain and grain boundary effect in the material. © 2012 VBRI press. Source


Sujatha C.,National Institute of Technology Warangal | Venugopal Reddy K.,National Institute of Technology Warangal | Sowri Babu K.,National Institute of Technology Warangal | Ramachandra Reddy A.,National Institute of Technology Warangal | Rao K.H.,RGU IIIT
Ceramics International | Year: 2013

Ni0.50Cu0.05Zn0.45Fe2O 4 ferrite nanoparticles were processed through the sol-gel method using polyvinyl alcohol as a chelating agent. The dried powder after annealing (500 °C for 3 h) was compacted and sintered at three different temperatures (900, 950 and 1030 °C) for 1 h. In this article, optimum sintering temperature required for NiCuZn ferrite system, for obtaining good electromagnetic properties, suitable for Multilayer Chip Inductor (MLCIs) applications was studied. The structural, magnetic and dielectric properties were investigated as a function of sintering temperature. X-ray diffraction patterns for the sintered samples confirmed formation of single phase cubic spinel structure. Microstructure and grain size distribution for the samples were investigated by FESEM which displayed homogeneous grains of polyhedral shape by retaining almost temperature independent grain shape but with increased grain size along with the increase of sintering temperature. Saturation magnetization showed increasing trend with sintering temperature up to 950 °C and decreased after that. The sample sintered at 950 °C exhibited low magnetic losses, high saturation magnetization and high frequency stability of permeability with cut off frequency around 30 MHz. © 2012 Elsevier Ltd and Techna Group S.r.l. Source


Sahoo P.S.,Betnoti College | Sahoo M.P.K.,RGU IIIT | Choudhary R.N.P.,ITER
Journal of Materials Science: Materials in Electronics | Year: 2012

A new member of tungsten bronze family, Ba 2Sr 3DyTi 3V 7O 30, was synthesized by a high-temperature solid-state reaction method. Studies of structural by X ray diffraction technique and micro-structural by scanning electron microscope brings out orthorhombic crystal structure and densely packed nonuniform grains for the above ceramic system. Detailed dielectric studies as a function of temperature (30-500 °C) at different frequencies (1-1,000 kHz) reveals diffuse-phase-transition and loss anomaly at 81 °C. Detailed studies of impedance parameters provide a better understanding of the electrical properties and type of relaxation processes in the material. Temperature variation of dc and ac conductivity shows that this compound exhibits negative temperature coefficient of resistance. The frequency variation of ac conductivity shows that the compound obeys Jonscher's universal power law. © 2012 Springer Science+Business Media, LLC. Source


Ravikirana K.,RGU IIIT | Rajasekhar B.,RGU IIIT | Laxmi Bhavani P.,RGU IIIT | Pavithra O.,RGU IIIT | And 3 more authors.
Journal of Corrosion Science and Engineering | Year: 2014

The present study discusses the effect of heat treatment on mechanical properties and corrosion behaviour of ASTM A36. Steel which contains 0.26% C is annealed at 830°C and 870°C followed by cooling in water and air. Effect on hardness, microstructural changes and corrosion behaviour were investigated. The resulting microstructures had ferrite-plus-pearlite for annealed and normalized samples, whereas for quenched sample it is martensite-plus-ferrite. The value of ultimate tensile strength was observed to higher for the hardened specimen possibly as a result of the refinement of the primary phase after the subsequent cooling processes, followed by tempered, normalized and annealed specimens. The value of hardness is observed to be in the order of hardened > tempered > normalised > annealed. The corrosion of mild steel in 0.5 N hydrochloric acid has been investigated by weight loss and potentiodynamic polarization techniques. The heat treated specimensexhibited better corrosion resistance than as received specimen. © 2014 University of Manchester and the authors. Source


Neeraja D.,RGU IIIT | Neeraja D.,Vellore Institute of Technology | Prasad B.,RGU IIIT | Prasad B.,Vellore Institute of Technology | And 3 more authors.
Journal of Corrosion Science and Engineering | Year: 2014

The main aim of the work is to study the changes in mechanical, metallographic and corrosion behavior of the Manganese bronze specimens before and after the heat treatment processes with varying temperatures and at a constant time. The Manganese bronze specimens were subjected to various heat treatment processes such as annealing, normalizing and quenching in water media at 250°C, 350°C, 400°C and 600°C for a 60 minute soaking time.Weight loss experiments showed that the heat treatment in the range of 250°C to 350°C is optimum for corrosive environments. The electrochemical (Corrosion response of the specimens exhibiting the low corrosive rates at 350°C annealed temperature. © 2014 University of Manchester and the authors. Source

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