Investigating the relaxor-kind phase transition

Characterization of Polar Oxides by Photo-Induced Light Scattering 

These results clearly demonstrate that the relaxor-kind phase transition determines the appearance of photo-induced light scattering, and therefore its temperature dependence can be used as a method for optical investigation of phase transitions. E.g., the transition temperature can be determined by the asymmetry parameter as a measure for the symmetry of the scattering pattern or by the comparably simple measurement of the directly transmitted laser beam. 

4 Determination of material parameters gain factor T, effective electro-optic coefficient (( reff) and effective trap density AAir 

The scattering pattern contains additional information about the scattering process itself as well as for the determination of material parameters. We will demonstrate in the following, that both the angular dependence of the holographic gain and the product of the effective linear electro-optic coefficient with the electron-hole competition factor as well as the effective trap density can be determined from the spatial distribution of the scattering pattern as a function of temperature [7], 

We assume that the intensity of the initially scattered light from a single scattering center is the same for symmetric scattering angles 9S. This assumption does not imply that the inten- 

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These properties demonstrate that the study of photo-induced light scattering can be used to investigate the relaxor-kind phase transition by an optical method. Hereby, various measures can be used, like the temperature dependence of the intensity of the directly transmitted laser beam, of the integrated scattered light and of the intensity ratio R, respectively, as shown in Figure 9.9. 

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