STUDY ON EFFECT OF ISOVALENT BARIUM IONS SUBSTITUTION ON STRUCTURAL FEATURES, FERROELECTRIC PROPERTIES AND BANDGAPS OF LEAD TITANATE
Abstract
- Isovalent Ba ions substituted lead titanate is studied by means of its structural features, ferroelectric properties and bandgaps. Analar grade PbO, TiO2 and BaCO3 are chosen and used as starting materials. Three starting materials are weighted and mixed by the stoichiometric composition: Pb(1 – x) Ba(x), TiO3, where x = 0, 1 mol%, 2 mol%, 3 mol%, 4 mol% and 5 mol% respectively. The mixture powders are grinded by using agate mortar for each 5 hrs. Then, the mixture powders are conventionally sintered at 700°C for each 5 hrs. After first sintering process, the mixture powders are grinded again by using ball milling for each 5 hrs. Finally, the mixture powders are sintered at 700°C for each 5 hrs. X – rays diffraction technique is used to examine the phase formation and structural features of PbTiO3:Ba specimens. From the XRD studies, lattice constants, lattice distortion, unit cell volume, crystallite size and lattice micro strain are estimated. Ferroelectric properties of PbTiO3:Ba specimens are characterized by using Sawyer – Tower circuit. Spontaneous polarization, remaent polarization and coercive field of PbTiO3:Ba specimens are evaluated. Optical bandgaps of PbTiO3: Ba specimens are studied by using UV – Vis spectrophotometer. From the absorption spectra, bandgaps are calculated. XRD results indicates that, there are no significant change of tetragonal perovskite type PbTiO3 structure after Ba substitution. A little changes of structural features are observed and it is due to appearance of micro strain and defects, dislocations and vacancies in host PbTiO3 structure during the doping mechanism. Ferroelectric properties, such as spontaneous polarization, remanent polarization and coercive field slightly increase as additional Ba content increases, due to second- order hybridizations, caused by isovalent Ba ions in PbTiO3 lattice. Optical bandgap of PbTiO3 is enhanced when additional Ba content is raised. It is expected that, there are a quantum confinement effect in PT: Ba specimens.
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Year
- 2021
Author
-
Pwint Yi Thein
Subject
- Physics
Publisher
- Myanmar Academy of Arts and Science (MAAS)