UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

Guest
2024-11-23 17:54
 HOME     CONFERENCES     SEARCH            LOGIN     NEW USER     IMAGES   


Conference: Bucharest University Faculty of Physics 2014 Meeting


Section: Solid State Physics and Materials Science


Title:
Ceramic BaTiO3 doped with Ce – dielectric properties


Authors:
Georgiana DUMITRACHE, D. BALAN, D. DRAGOMIR, C. BERBECARU


Affiliation:
Faculty of Physics, University of Bucharest, Bucharest – Magurele, 077125, Romania



E-mail
georgianaa.dumitrache@yahoo.com, danutz_nightshot@yahoo.com, adrianrider91@yahoo.com, berbecaru2ciceron@yahoo.com


Keywords:
ceramics, BaTiO3 doped with Ce, permittivity and loss, relaxor


Abstract:
Dielectric properties of pure Barium Titanate (BT) and 5.4 mol. % Ce3+ doped BaTiO3 (BT:Ce) were investigated on extended temperatures and frequency ranges with the aid of a self-acting RLC bridge in line with a computer for data registration and further investigations. Pure BaTiO3 ceramics show characteristic phase transitions temperatures in the -150 ÷ +150 oC range, whereas BT:Ce ceramics displays decreasing values of them. Permittivity values of the BT ceramics decreases in the BT:Ce doped materials due to the substitution of Ba2+ with Ce3+ ions. Losses show comparable values for both BT and BT:Ce ceramics which suggested a good charge compensation. At higher than 100 oC and for low frequency values, some thermally activated mechanisms increase losses value, probably due to the electrons and vacancies always present in these materials obtained by solid state sintering method. Permittivity of the BT:Ce ceramics shows decreasing values in the 42 ÷ 106 Hz frequency range having a slow shift of the Curie temperatures with the frequencies increase. At constant temperatures permittivity and losses values present a pronounced dispersion if the ceramics are in the ferroelectric phase versus paraelectric state. Doped ceramics display increased and shifted values of losses, toward high frequencies, up to Curie temperature and decreased ones above ferroelectric phase transition with the increasing of frequency values. These figures suggest a relaxor like behavior of the BT-Ce ceramics even for low Ce content.