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Bhawānipatna, India

Pati B.,Siksha O' Anusandhan University | Pati B.,Government Junior College | Choudhary R.N.P.,Siksha O' Anusandhan University | Das P.R.,Siksha O' Anusandhan University
Journal of Alloys and Compounds | Year: 2013

The current research work reports the study of phase transition and transport mechanism in lead-free strontium orthovanadate (Sr3V 2O8), prepared using a higherature solid-state reaction technique. Preliminary X-rays diffraction studies exhibit the formation of a single-phase compound in the trigonal crystal system. Study of microstructure of gold-coated pellet by scanning electron microscopy (SEM) shows well-defined and homogeneous grains in the morphology. Detailed studies of dielectric parameters (ε r and tanδ ) of the compound as a function of temperature at some selected frequencies reveal their independence for a wide range of temperatures. An anomaly in relative permittivity (εr) suggests the existence of a ferroelectric-paraelectric phase transition of diffuse-type in the material that confirms through the detailed studies of its electric polarization. Detailed studies of impedance and related parameters exhibit that the electrical properties of the material are strongly dependent on temperature, and bear a good correlation with its microstructure (i.e., bulk, grain boundary, etc.). The decrease in value of bulk resistance on increasing temperature suggests the negative temperature co-efficient of resistance (NTCR) behavior of the material. Studies of electric modulus indicate the presence of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The nature of variation of dc conductivity with temperature confirms the Arrhenius and NTCR type of behavior in the material. The ac conductivity spectrum shows a typical-signature of an ionic conducting system, and is found to obey Jonscher's universal power law. © 2013 Elsevier B.V. All rights reserved.


Pati B.,Siksha O' Anusandhan University | Pati B.,Government Junior College | Choudhary R.N.P.,Siksha O' Anusandhan University | Das P.R.,Siksha O' Anusandhan University
Ceramics International | Year: 2014

The current research work reports on structural, dielectric, pyroelectric and conduction properties of strontium orthotantalate, prepared by using a high-temperature solid-state reaction technique. Preliminary x-rays structural study of the material confirms the formation of a single-phase compound with trigonal crystal structure. The microstructure of gold-coated pellet sample recorded by scanning electron microscopy (SEM) shows well-defined and homogeneously distributed grains. Detailed studies of dielectric parameters (εr and tan δ) of the compound as a function of temperature at some selected frequencies reveal that these parameters are invariant in a wide range of frequency and temperature (room temperature to about 400 C). Studies of pyroelectric properties reveal that the materials have reasonably high figure of merit useful for fabrication of pyroelectric detector. The ac conductivity spectra show a typical-signature of an ionic conducting system, and are found to obey Jonscher's universal power law. The low leakage current and negative temperature coefficient of resistance (NTCR) behavior of the sample have been verified from J~E plots. The nature of variation of dc conductivity with temperature confirms the Arrhenius and NTCR behavior in the material. © 2013 Elsevier Ltd and Techna Group S.r.l.


Ramana P.V.,Government Junior College | Byragi Reddy T.,Andhra University
Research Journal of Pharmaceutical, Biological and Chemical Sciences | Year: 2012

The paper deals with general floristic account of Kaviti Mandalam, Srikakulam district, Andhra Pradesh. A brief description of vegetation and topography is given. 360 Species belonging to 267 genera and 100 families are enumerated, of which 9 species belonging to Pteridophytes. Fabaceae, Euphorbiaceae, Asteraceae, Poaceae, Rubiaceae, Malvaceae, Apocynaceae are the dominant families. Nearly forty species are newly added to the District Flora.


Choudhary R.N.P.,Siksha O' Anusandhan University | Pati B.,Siksha O' Anusandhan University | Pati B.,Government Junior College | Das P.R.,Siksha O' Anusandhan University | And 2 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2014

The current research work presents the preparation and characterization of some new electronic materials using bismuth oxide (Bi2O3) and industrial waste red mud in different proportion by weight using a cost-effective mixed-oxide technique. Preliminary X-ray structural analysis exhibits the formation of compounds with structure analogous to that of BiFeO3 compound along with some impurity phases. Studies of dielectric parameters (er and tand) of these compounds as a function of temperature and frequency exhibit that they are almost temperature independent in the low temperature range and possess high relative permittivity with low loss in the high temperature range. Detailed studies of impedance and related parameters exhibit that the electrical properties of these materials are strongly dependent on temperature, and bear a good correlation with their microstructures. The bulk resistance, evaluated from complex impedance spectra, is found to be decreasing with rise in temperature, exhibiting a typical negative temperature co-efficient of resistance (NTCR)- type behavior similar to that of semiconductors. Studies of electric modulus indicate the presence of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The low leakage current and NTCR behavior of the sample have been verified from I-V characteristics. The nature of variation of dc conductivity with temperature confirms the Arrhenius and NTCR behavior in the material. The ac conductivity spectra show a typical-signature of an ionic conducting system, and are found to obey Jonscher's universal power law. © Springer Science+Business Media New York 2013.


Pati B.,Siksha O' Anusandhan University | Pati B.,Government Junior College | Choudhary R.N.P.,Siksha O' Anusandhan University | Das P.R.,Siksha O' Anusandhan University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

The present study highlights ferroelectric phase transition, dielectric, pyroelectric properties and conduction mechanism of highly crystallized barium orthoniobate (Ba3Nb2O8) ceramic, prepared by a solid-state reaction technique. X-ray diffraction studies show the formation of a single-phase compound in hexagonal crystal system. Detailed studies of dielectric parameters (εr and tan δ) of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and frequency. An anomaly in εr suggests the possible existence of a ferroelectric-paraelectric phase transition of diffuse-type in the material. The low dielectric loss and moderate relative permittivity make this material (with certain modification) a potential candidate for microwave applications. Studies of pyroelectric properties reveal that the materials have reasonably high figure of merit useful for fabrication of pyroelectric detectors. The low-leakage current and negative temperature coefficient of resistance (NTCR) behavior of the sample have been verified from J-E plots. The nature of variation of dc conductivity with temperature confirms the Arrhenius and NTCR behavior of the material. © 2014 Elsevier B.V. All rights reserved.

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