Dielectric and magnetic properties of Fe and Ti based perovskite oxides

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dc.contributor.author Deka, Bipul
dc.date.accessioned 2020-08-10T08:17:33Z
dc.date.available 2020-08-10T08:17:33Z
dc.date.issued 2017
dc.identifier.other ROLL NO.11612112
dc.identifier.uri http://gyan.iitg.ernet.in/handle/123456789/1556
dc.description Supervisors: S. Ravi and A. Perumal en_US
dc.description.abstract The present PhD thesis deals with extensive investigation of magnetic and dielectric properties of (1) YFe1-xMnxO3 (x = 0 to 0.3), (2) Bi1-xSmxFeO3 (x = 0 to 0.3), (3) PbTi1-xFexO3 (x = 0 to 0.3) and (4) BaTi1-xFexO3 (x = 0 to 0.3) samples. Study of complex impedance spectra, dielectric constant and ac electrical conductivity of YFe1-xMnxO3 (x = 0 – 0.3) compounds elucidates the role played by both grains and grain boundaries in shaping the dielectric relaxation. The relaxation is attributed to the short-range movement of oxygen vacancies. The Nyquist plots of complex impedance were analyzed by fitting them to an equivalent electrical circuit. This circuit contains three parts connected in series: first one is the electrode resistance (RE); second one is the parallel combination of resistance and capacitance of grains (RG ,CG) and the third one is the parallel combination of resistance and constant phase element of grain boundaries (RGB, QGB). Mn substitution is found to decrease the Néel temperature from 646 K to 428 K and induce spin reorientation transition at low temperature from 4 (AxFyGz) to 1 (GxCyAz) spin configuration. The spin reorientation transition temperature is found to increase from 81 K for x = 0.1 to 295 K for x = 0.3. These samples exhibit interesting exchange bias behavior above room temperature with a maximum exchange bias field of 1.2 kOe at 413 K. en_US
dc.language.iso en en_US
dc.relation.ispartofseries TH-1694;
dc.subject PHYSICS en_US
dc.title Dielectric and magnetic properties of Fe and Ti based perovskite oxides en_US
dc.type Thesis en_US

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