INVESTIGATION OF DIELECTRIC AND PYRO-ELECTRIC PROPERTIES OF AZO DYE (CHR): PVA COMPOSITE.
Journal Title: ASIAN JOURNAL OF NATURAL & APPLIED SCIENCES - Year 2013, Vol 2, Issue 2
Abstract
In this article, we present the thermally stimulated depolarization currents (TSDC), dielectric properties and pyro- electric investigations of electrically poled azo dye (chromotrope -2R (CHR) doped poly (vinyl alcohol) (PVA) thin films. Based on dielectric spectroscopy data, the pyroelectricity have been explained with reversible dipole density changes during thermal expansion, whereas increase in dielectric constant has been explained in terms of polarization caused by charge carriers, probably ions. The thermally stimulated depolarization currents (TSDC) in azo dye: PVA has been investigated in the temperature range 30 - 120°C. Two distinct peaks of TSDC spectra were observed at approximately 65°C ( α–peak ) and 110°C (ρ-peak ). The α –peak and ρ -peak in the TSDC spectra are originated from the dipolar process and space charge relaxation, respectively. The effect of azo dye (CHR) on dielectric and polarization properties of PVA was also investigated. Dielectric studies showed the relaxor behavior with diffuse phase transition. It is found that the dielectric dispersion in the film support the well known Vogel-Fulcher law. The pyroelectric coefficient of electrically poled PVA: CHR thin film goes upto 0.4 µC/m 2 K at room temperature. It is concluded from the observations that the orientation of strong anisomeric side chain takes place with a degree of alignment of about 8 %.
Authors and Affiliations
Raj Kumar, G. D. Sharma , M. S. Roy
Keywords
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