| |
 |
UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:33 |
 |
|
|
|
Conference: Bucharest University Faculty of Physics 2011 Meeting
Section: Solid State Physics and Materials Science
Title:
Relaxation mechanism and dielectric dispersion in TGS crystals
Authors:
Carmen Mindru, C. Berbecaru and H. V. Alexandru
Affiliation:
Faculty of Physics, University of Bucharest, Romania
E-mail
hvalexandru@gmail.com , krmen63@yahoo.com , berbecaru2ciceron@yahoo.com
Keywords:
Triglycine sulphate crystals; dielectric spectroscopy; permittivity relaxation
Abstract:
Triglycine sulphate crystal (TGS for short) has important applications in electronic. Pyroelectric vidicon tubes have crystals from the TGS family as target materials. Pure TGS crystals have a complicated topography and evolution of the ferroelectric domains. They show a peculiar dielectric behavior in the ferroelectric phase, after crossing down the Curie Point (CP) from the paraelectric phase. Dielectric dispersion of pure TGS was investigated in the frequency range 45 Hz-5 MHz,from 65 oC to -150 oC. The two component of permittivity in a Cole-Cole representation, shows two type of relaxation in the ferroelectric phase, having characteristic times tauL~1ms and tauH~100ns. The lower relaxation time is related to ferroelectric domain wall relaxation (domain cropping). The higher “frequency” relaxation time is ascribed to the “critical slowing down” effect, similar to the system relaxation approaching CP in the paraelectric phase. Temperature dependence of Cole-Cole characteristic parameter alpha(T) and of both relaxation times was estimated and shall be discussed. In the close proximity of CP, there is a non-Arrhenius temperature behavior of all estimated parameters. Activation energy estimated on the temperature range down the CP, until room temperature; clearly indicate the different nature of the two type of relaxation in TGS.
|
|
|
|