AVS 49th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Paper AS-WeM5
Application of Bragg Light Scattering Method for Studying of Spatial Dispersion Effects in Ferroelectrics

Wednesday, November 6, 2002, 9:40 am, Room C-106

Session: Optical Methods and High-k Dielectrics Characterization
Presenter: F.R. Akhmedzhanov, Samarkand State University, Uzbekistan
Correspondent: Click to Email
Bragg light scattering method for studying of spatial dispersion effects was applied to pure LiNbO@sub3@ and Mg doped LiNbO@sub3@ ferroelectrics. The examined samples of pure LiNbO@sub3@ and LiNbO@sub3@ with Mg impurity (10@super-2@ mol. %) were oriented along the axis of the third order with the accuracy of 10@SUPER'@. Piezoelectric transducers of Lithium Niobate of appropriate cuts are used in order to excite the plane-polarized transverse acoustic waves with the frequencies of 0.4-1.5 GHz. Measurements of the dependence of the scattered light intensity from the distance to the piezotransducer along the direction of the acoustic wave propagation have been carried out in automatic regime. The scattered light intensity can be presented as function dependence of the light intensity I with respect to distance Z of acoustic wave shift: I = I@subo@exp (-A*Z) Cos@super2@(D*Z + F), Here I@subo@ is the scattered light intensity near piezotransducer, A is the attenuation coefficient of the acoustic wave, D - the specific rotation angle of the polarization vector and F - the initial phase angle. The obtained values of the scattered light intensities have been used to calculate the quantity and frequency dependence of the attenuation and of the specific rotation of polarization vector in given acoustic wave by modeling of above-mentioned equation. The effective constants of acoustical activity along the investigated direction were determined from the experimental data simultaneously. There has been shown the high efficiency and trustworthiness of the results of simultaneous calculation of attenuation coefficient and specific rotation of the polarization plane in gyrotropic crystals, as well as possibility of speculation of experimental curves by varying factors, which are changed in a real experiment.