Betnoti College Betnoti

Mayurbhanj, India

Betnoti College Betnoti

Mayurbhanj, India
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Mohanty B.B.,Betnoti College Betnoti | Sahoo P.S.,North Orissa University | Choudhary R.N.P.,Siksha ‘O’ Anusandhan University
Journal of Materials Science: Materials in Electronics | Year: 2017

A series of polycrystalline samples of tungsten–bronze family is prepared having a general formula Ba5−xSrxGdTi3V7O30 (x = 0–5), and is synthesized by a high-temperature solid-state reaction technique. The formation, quality and basic crystal data (i.e., cell parameters and particle size) of the compounds were studied using X-ray diffraction data. Microstructural nature of the materials is studied using scanning electron microscope. The relative dielectric constant (εr) of the materials studied in a wide range of temperature (room temperature to 500 °C) and frequency (1 kHz to 1 MHz) exhibits diffuse phase transition in the system The transition temperature and relative dielectric constant of the compounds are found increasing on replacing vanadium (V) at the Nb-site of the parent compound (i.e. Ba5GdTi3Nb7O30). However, on increasing Sr concentration, transition temperature is found to decrease towards room temperature. © 2017 Springer Science+Business Media, LLC


Sahoo P.S.,Betnoti College Betnoti | Mohanty B.B.,Betnoti College Betnoti
Advanced Materials Letters | Year: 2014

The advent of nanoscience & technology have completely changed the orientation/direction of studies of eco-friendly (lead-free) materials bringing them at the forefront of scientific developments with considerably enhanced physical properties suitable for a wide variety of challenging applications. Barium based ferroelectric materials have gained much importance due to their vast applications as they possess high dielectric constant, non-linear spontaneous polarization, negative temperature coefficient of resistance behavior etc.. All these characteristics stimulated the researchers to replace toxic and hazardous lead based materials by barium based TB materials from industry. Our present research work deals with the synthesis of polycrystalline samples of Ba2Sr3RTi3V7O30 (R = Gd, Sm) by a high temperature solid state reaction technique and a comparative study of the electrical properties of the samples. Preliminary structural (XRD) analyses of these compounds show the formation of single-phase orthorhombic structures at room temperature having average crystallite size of the order of some nanometer for both the compounds. The electrical properties for both the samples are studied in a wide range of temperature (30-500°C) and frequency (100Hz-1MHz). The dielectric properties suggest that both the compounds have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 230 and 313°C for R= Sm and Gd respectively at frequency 100 kHz).The bulk resistance of the materials exhibits negative temperature coefficient of resistance behavior as observed in semiconductors. © 2014 VBRI press.


Mohanty B.B.,Betnoti College Betnoti | Sahoo P.S.,Betnoti College Betnoti
Journal of Rare Earths | Year: 2012

Barium based tungsten bronze (TB) oxides having high dielectric constant and low loss, can be effectively used as transducers, actuators, capacitors and also in memory devices. All these characteristics stimulated the researchers to replace toxic and hazardous lead based materials by barium based TB materials from industry. In the present research work, polycrystalline samples of Ba 4SrRTi3V7O30 (R=Dy, Sm, La) were synthesized by a high temperature solid state reaction technique. Preliminary structural (X-ray diffraction) analyses of these compounds showed the formation of single-phase orthorhombic structures at room temperature having average crystallite size of the order of some nanometer for all the compounds. The scanning electron micrographs (SEM) provided information on the quality of the samples and showed more or less homogeneous distribution of grains over the entire surface of the samples. Detailed dielectric study in a wide temperature range (30-500 °C) showed ferro to para phase transition for Dy and Sm substituted samples whereas no such transition was observed for La substituted samples. Both the grain and grain boundary resistances exhibited negative temperature coefficient of resistance behavior much like semiconductors. The dc conductivity of all the compounds obeyed Arrhenius relation. © 2012 The Chinese Society of Rare Earths.


Sahoo P.S.,Betnoti College Betnoti | Panigrahi A.,Dn College | Patri S.K.,Indian Institute of Technology Kharagpur | Choudhary R.N.P.,Indian Institute of Technology Kharagpur
Journal of Materials Science: Materials in Electronics | Year: 2010

Polycrystalline sample of Ba 5SmTi 3V 7O 30 was prepared by a high-temperature solid-state reaction technique. Structural and microstructural characterizations were performed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray preliminary structural studies reveal that the material has orthorhombic structure at room temperature. Detailed electrical (dielectric and impedance) properties of the material studied by using a complex impedance spectroscopy (CIS) technique in a wide temperature range (33-450 °C) at different frequencies (10 2-10 6 Hz) reveal that the relative dielectric constant of the material increases with rise in temperature and thus bulk has a major contribution to its dielectric and electrical properties. The bulk resistance of the material decreases with rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior. The nature of the temperature variation of conductivity and value of activation energy, suggest that the conduction process is of mixed-type (ionic-polaronic and space charge). The existence of ferroelectricity in the compound was confirmed from polarization study. © 2009 Springer Science+Business Media, LLC.


Sahoo P.S.,Betnoti College Betnoti | Panigrahi A.,Dn College | Patri S.K.,Indian Institute of Technology Kharagpur | Choudhary R.N.P.,Indian Institute of Technology Kharagpur
EPJ Applied Physics | Year: 2010

Strontium-substituted barium vanadates, Ba5-xSr xDyTi3V7O30 (x = 0-5), were prepared by a high-temperature sold-state reaction method. The formation of the materials was checked by X-ray diffraction technique. Preliminary structural analyses of the materials exhibit the formation of new compounds in orthorhombic structure. Surface morphology of the compounds was studied by scanning electron microscopy. The effect of Sr on microstructure of the materials has resulted in a modification of the electrical properties. Study of electrical properties using impedance analysis technique exhibit (i) the presence of negative temperature coefficient of resistance behavior, (ii) presence of temperature dependent electrical relaxation phenomena, (iii) evidences of single electrical relaxation attributed to the presence of bulk contribution to the electrical properties, (iv) an enhancement in the barrier to the mobility of charge carriers on Sr-substitution. The effects of Sr in the electrical conductivity as a function of temperature at different frequency are explained in impedance spectrum analyses. © 2010 EDP Sciences.


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.


Mohanty B.B.,Betnoti College Betnoti | Sahoo P.S.,Betnoti College Betnoti | Choudhary R.N.P.,Siksha ‘O’ Anusandhan University
Advanced Science Letters | Year: 2016

Polycrystalline samples of Ba5RTi3V7O30 (R = Dy, Sm, Gd) are prepared by Mixed Oxide Process. The X-ray diffractograms at room temperature of these compounds show that the compounds have single-phase orthorhombic structure. The microstructures of the samples are studied from SEM micrographs, which show that the grains are non-uniformly distributed over the entire surface of all the samples. In this work the effect of Rare earth ion substitution on the electrical properties of this sample is studied using impedance spectroscopy. The present dielectric ceramics exhibited ferroelectric-paraelectric phase transition at temperatures around 441 and 385 °C for Ba5 Ti3DyV7O30 and Ba5GdTi3V7O30 respectively where as no phase transition is observed for Ba5Ti3SmV7O30 compound. © 2016 American Scientific Publishers. All rights reserved.


Sahoo P.S.,Betnoti College Betnoti | Mohanty B.B.,Betnoti College Betnoti | Choudhary R.N.P.,ITER
Advanced Science Letters | Year: 2016

BaSr4LaTi3V7O30, a ferroelectric compound with tungsten-bronze structure, is synthesized by high-temperature mixed oxide process. The formation of single-phase orthorhombic structures is confirmed from the room temperature XRD analysis. The quality and non-uniform distribution of grains over entire surface of the sample is obtained from SEM micrograph. The temperature dependent impedance parameters are studied using an impedance analyzer in a wide range of frequency (102–106 Hz) and temperature (30 °C–500 °C). The electrical properties studied using impedance analyser show; (i) the presence of negative temperature coefficients of resistance behavior, (ii) presence of temperature dependent electrical relaxation phenomena, (iii) evidences of single electrical relaxation attributed to the presence of bulk contribution to the electrical properties. The nature of variation of dc conductivity suggests Arrhenius type of electrical conductivity. © 2016 American Scientific Publishers. All rights reserved.


Sahoo P.S.,Betnoti College Betnoti | Mohanty B.B.,Betnoti College Betnoti | Choudhary R.N.P.,Siksha ‘O’ Anusandhan University
Advanced Science Letters | Year: 2016

Gadolinium modified barium strontium vanadates, BaSr4GdTi3V7O30, were synthesized by a Mixed Oxide Reaction process. The material formed was checked by X-ray diffraction method. The structural analyses of the material show the formation of single-phase orthorhombic structures. Detailed studies of dielectric properties as a function of temperature (33 °C–500 °C) and frequencies (102–106 Hz) inform the frequency independent diffused dielectric anomaly of the compound at a temperature ∼185 °C. This may be related to ferroelectric phase transition which is confirmed from polarization study. The value of activation energy calculated from the temperature dependent ac conductivity graph in different regions, indicate that the mixed type (i.e., ionic–polaronic and space charge created from the oxygen ion vacancies) conduction process. © 2016 American Scientific Publishers. All rights reserved.


Mohanty B.B.,Betnoti College Betnoti | Sahoo P.S.,Betnoti College Betnoti | Choudhary R.N.P.,Siksha ‘O’ Anusandhan University
Advanced Science Letters | Year: 2016

Ba5LaTi3V7O30, a compound belonging to tungsten bronze ferroelectric ceramics is prepared by using a hightemperature solid-state reaction technique. The XRD analysis of the compound shows the formation of an orthorhombic compound at room temperature. The scanning electron microscopic (SEM) study provides information on quality of the sample and the non uniform grain distribution over the entire surface of the sample. The present dielectric ceramic exhibits diffused ferroelectric phase transition at temperature around 68 °C. Detailed studies of dielectric properties of Ba5LaTi3V7O30, investigated in a wide frequency range (103–106 Hz) at different temperatures (33°–500 °C) showed that these properties of the material are strongly dependent on frequency and temperature. The activation energy calculated in different regions from the temperature dependence ac conductivity (dielectric data) plot suggest that the conduction process in the material is because of the ionicpolaronic and space charge created due to oxygen ion vacancies. The frequency dependent ac conductivity curves obey Jonscher’s universal power law. © 2016 American Scientific Publishers. All rights reserved.

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