Calculation of the Damping Constant and the Relaxation Time for the Soft-Optic and Acoustic Mode in Hexagonal Barium Titanate

2012-01-01
The temperature dependence of the damping constant is calculated below the transition temperature (T-0 = 222K) in the ferroelectric phase of hexagonal barium titanate. The damping constant of the coupled soft-optic and acoustic mode which causes an intense central peak in the light scattering spectra, is calculated using the soft mode-hard mode coupling model and the energy fluctuation model for barium titanate.

Suggestions

Calculation of the Spontaneous Polarization and the Dielectric Constant as a Function of Temperature for KH2PO4
Yurtseven, Hasan Hamit (2012-01-01)
The temperature dependence of the spontaneous polarization P is calculated in the ferroelectric phase (T < T-C) of KH2PO4 (KDP) at atmospheric pressure (T-C = 122 K). Also, the dielectric constant e is calculated at various temperatures in the paraelectric phase (T > T-C) of KDP at atmospheric pressure. For this calculation of P and epsilon, by fitting the observed Raman frequencies of the soft mode, the microscopic parameters of the pure tunnelling model are obtained. In this model, the proton-lattice inte...
Critical behaviour of ammonia near the melting point
Yurtseven, Hasan Hamit (2002-08-01)
This study gives our calculations for thermodynamic quantities, such as the isothermal cornpressibility k(T), thermal expansivity alphap and the specific heat C-P, as a function of temperature for solid ammonia near the melting point. Our calculations, which have been performed on the basis of an experimental study given in the literature, show that those thermodynamic quantities diver e near the melting point in ammonia. This is an indication that ammonia exhibits a critical transition as one approaches th...
Temperature Dependence of the Raman Frequency, Damping Constant and the Activation Energy of a Soft-Optic Mode in Ferroelectric Barium Titanate
Kiraci, A.; Yurtseven, Hasan Hamit (2012-01-01)
The Raman frequency of a soft-optic mode associated with the order parameter is calculated as a function of temperature from the mean field theory for barium titanate (T-C = 222K). Using the Raman frequencies calculated, the damping constant is evaluated and it is compared with the observed one for this soft-optic mode.
Calculation of the raman frequency, damping constant (Linewidth) and the relaxation time near the tetragonal-cubic transition in PbTiO3
KİRACI, ALİ; Yurtseven, Hasan Hamit (2017-01-01)
Frequencies, damping constants and the relaxation times of some Raman modes including the two soft modes are calculated as a function of pressure near the tetragonal-cubic transition in PbTiO3. Calculation of the Raman frequencies is performed using the observed volume data from the literature by means of the mode Gruneisen parameter at various pressures. Pressure dependence of the damping constant and the relaxation time is predicted using the pseudospin-phonon coupled model and the energy fluctuation mode...
Calculation of the damping constant and the order parameter for the lattice mode in ferroelectric PbTiO3
Kiraci, A.; Yurtseven, Hasan Hamit (2013-07-25)
The temperature dependences of the damping constant and the order parameter are calculated for the lattice mode of E (1TO) in PbTiO3 using the experimental data by the pseudospin- phonon coupled model and the enrgy fluctuation model. Calculation of the damping constant of soft mode is performed in the temperature range of 400- 490 degrees C close to the ferroelectric- paraelectric transition (T-C= 493 degrees C) in PbTiO3. By relating the frequency to the order parameter, the temperature dependence of the R...
Citation Formats
H. H. Yurtseven, “Calculation of the Damping Constant and the Relaxation Time for the Soft-Optic and Acoustic Mode in Hexagonal Barium Titanate,” FERROELECTRICS, pp. 137–148, 2012, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/49043.