NISCAIR Online Periodicals Repository

NISCAIR ONLINE PERIODICALS REPOSITORY (NOPR)  >
NISCAIR PUBLICATIONS >
Research Journals >
Indian Journal of Engineering and Materials Sciences (IJEMS) >
IJEMS Vol.15 [2008] >
IJEMS Vol.15(2) [April 2008] >


Title: Studies on dielectric behaviour of an oxygen ion conducting ceramic – CaMnO₃₋δ
Authors: Pandey, Namita
Thakur, Awalendra K
Choudhary, R N P
Issue Date: Apr-2008
Publisher: CSIR
Abstract: An oxygen deficient ceramic oxide having perovskite structure has been prepared by the conventional solid state reaction method. X–ray diffraction studies have confirmed the sample formation in single phase polycrystalline form. The scanning electron micrographs have confirmed polycrystalline texture of the material alongwith indications of porous microstructure. The temperature dependence of the dielectric properties (permittivity/loss tangent) in the sub-ambient and ambient temperature region suggests the possibility of a strong dipolar ordering. The appearance of maxima in both the permittivity and loss factor pattern at a very close temperature range (Ɛmax~1879 at 29oC, tan δmax~9.7 at 35oC at a common frequency of 10 kHz) supports the presence of dipolar interaction in CaMnO3-. It has been attributed to a strong interaction of the oxide ion-oxygen vacancy pair in the crystal lattice of an oxygen deficient perovskite (CaMnO₃₋) that in turn reduces the net mobility of oxygen ion at lower temperatures and imparts it a higher dielectric permittivity as well as high loss factor close to room temperature. A decrease in the permittivity and monotonous increase in loss factor with rise in temperature above the ambient value suggest a thermally activated weakening of the dipolar ordering in the system. In view of a very high value of loss factor at and above room temperature, it would be premature to conclude the existence of ferroelectric ordering in the material system just by the presence of a peak in both the permittivity and loss factor pattern.
Page(s): 191-195
ISSN: 0971-4588
Source:IJEMS Vol.15(2) [April 2008]

Files in This Item:

File Description SizeFormat
IJEMS 15(2) 191-195.pdf270.39 kBAdobe PDFView/Open
 Current Page Visits: 617 
Recommend this item

 

National Knowledge Resources Consortium |  NISCAIR Website |  Contact us |  Feedback

Disclaimer: NISCAIR assumes no responsibility for the statements and opinions advanced by contributors. The editorial staff in its work of examining papers received for publication is helped, in an honorary capacity, by many distinguished engineers and scientists.

CC License Except where otherwise noted, the Articles on this site are licensed under Creative Commons License: CC Attribution-Noncommercial-No Derivative Works 2.5 India

Copyright © 2012 The Council of Scientific and Industrial Research, New Delhi. All rights reserved.

Powered by DSpace Copyright © 2002-2007 MIT and Hewlett-Packard | Compliant to OAI-PMH V 2.0

Home Page Total Visits: 574966 since 06-Feb-2009  Last updated on 26-Aug-2014Webmaster: nopr@niscair.res.in