Pressure dependence of the Raman frequency calculated from the volume data close to the ferroelectric-paraelectric transition in PbTiO3

2017-01-01
We calculate the pressure dependence of the Raman frequencies of some Raman modes by using the observed volume data through the mode Gruneisen parameters for the ferroelectri-paraelectric transition in PbTiO3. The mode Gruneisen parameters which we have determined using the observed Raman frequencies for the soft modes, increase considerably with increasing pressure toward the transition pressure (PC similar to 11 GPa) from the tetragonal (ferroelectric) to the cubic (paraelectric) phase in PbTiO3. Variation of the mode Gruneisen parameter with the pressure is rather smooth for the other Raman modes studied as compared to the drastic change at PC for the soft modes in this ferroelectric material. Raman frequencies (energy shifts) of the modes which we have calculated, decrease from the ferroelectric to the paraelectric phase with the exception of the optical modes of E(3LO) and E(3TO) whose Raman frequencies increase with increasing pressure.

Suggestions

Temperature and Pressure Effect on the Raman Frequencies Calculated from the Crystal Volume in the gamma-Phase of Solid Nitrogen
Yurtseven, Hasan Hamit (Springer Science and Business Media LLC, 2015-09-01)
The temperature and pressure dependences of the Raman frequencies of the lattice modes (E-g and B-1g modes) and of an internal mode (2331 cm(-1)) are predicted using the observed molar volume data from the literature in the gamma-phase of solid N-2. This calculation is carried out by means of the mode Gruneisen parameter of each Raman mode in the gamma-phase of solid nitrogen. Our results show that the predicted Raman frequencies of the E-g mode increase as the pressure increases. The Raman frequencies of t...
Temperature and pressure dependence of the Raman frequency shifts in anthracene
Ozdemir, H.; Yurtseven, Hasan Hamit (2016-08-01)
In this study, the Raman frequency shifts of phonons and vibrons of crystalline anthracene as functions of temperature (at zero pressure) and pressure (at ambient temperature) have-been calculated using the experimental volume data from the literature. This calculation is performed for six phonons and nine vibrons through the mode Gruneisen parameters which have been determined from the Raman frequency and volume data at various pressures. Our predicted Raman frequencies of the phonon modes decrease with in...
Calculation of the Raman and IR frequencies from the volume data at high pressures in N-2
AKAY, ÖZGE; Yurtseven, Hasan Hamit (2018-01-01)
Raman and IR frequencies of N-2 in the molecular state are calculated as a function of pressure up to 160 GPa by using the volume data from the literature through the mode Gruneisen parameter. By determining the Gruneisen parameters for the lattice modes and vibrons which decrease mostly with increasing pressure from the observed frequency (Raman, IR) and volume data, the Raman and IR frequencies of those modes are calculated at various pressure at room and low temperatures. We find that the Raman and IR fr...
Raman frequencies calculated as functions of temperature and pressure using volume data for solid phase I of benzene
Yurtseven, Hasan Hamit (2017-01-01)
Raman frequencies of six lattice modes are calculated as a function of pressure using the volume data from the literature by means of the isothermal mode Gruneisen parameter (gamma(T)) for the solid phase I of benzene. We find that by determining the yr decreasing, the Raman frequencies calculated for the phonon modes increase with increasing pressure in this solid phase of benzene, which agree with the observed Raman data. We also predict the T-P phase diagram between the solid phases of I and I' by using ...
Temperature dependence of the mode Gruneisen parameter in the vicinity of the lambda-transition point in NH4Cl
Karacali, H.; Yurtseven, Hasan Hamit (2006-11-01)
This study gives our relations between the specific heat C P and the Raman frequency shifts (1/v)(partial derivative v/partial derivative T)(p) for the lattice modes of v(5) (144 cm(-1)) and v(5) (174 cm(-1)), when the mode Gruneisen parameter gamma(p) depends on the temperature near. the lambda-transition in NH4Cl (T-lambda = 242.5 K, P = 0).
Citation Formats
H. H. Yurtseven, “Pressure dependence of the Raman frequency calculated from the volume data close to the ferroelectric-paraelectric transition in PbTiO3,” FERROELECTRICS, pp. 245–255, 2017, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/43052.