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Fizik Bilim Dalı Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/4363

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Browsing Fizik Bilim Dalı Yayın Koleksiyonu by Subject "Damping Constant"

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    Article
    Damping constant and the inverse relaxation time calculated as a function of pressure using the X-ray diffraction data close to the cubic-tetragonal phase transition in SrTiO3
    (2019) Kiracı, Ali; Kiracı, Ali; 42475
    The damping constant is calculated as a function of pressure at room temperature using the normalized intensity as an order parameter near the cubic-tetragonal phase transition in SrTiO3. The observed X-ray diffraction data are used for the normalized intensities to calculate the damping constant () from the pseudospin-phonon (PS) coupled model and the energy fluctuation (EF) model, which is fitted to the observed FWHM data from the literature for comparison. Using the calculated values, the pressure dependence of the inverse relaxation time () is predicted close to the cubic-tetragonal phase transition in SrTiO3. Our calculated damping constant from both models explains the observed FWHM satisfactorily and our prediction of the inverse relaxation time can also be compared with the experimental measurements when they are available in the literature.
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    Article
    Order-disorder transition in the ferroelectric LiTaO3
    (2019) Kiracı, Ali; Yurtseven, Hamit; 42475
    The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A(1) (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO3 (T-C = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin-phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order-disorder transition in LiTaO3.