Calculation of the soft mode frequency for the alpha beta transition in quartz

2015-09-18
The Raman frequencies of the lattice modes (147 cm-1 and 207 cm-1 are analyzed for the α-β transition in quartz according to a power-law formula with the critical exponent by using the experimental data. The temperature dependence of the Raman frequency is associated with the order parameter (polarization P) for this transition in the quartz crystal. The damping constant of the lattice modes studied here is calculated using the Raman frequencies at various temperatures for the α-β transition in quartz (Tc = 846K) using the soft mode - hard mode and the energy fluctuation models. Our calculations for the damping constant (bandwidths) give an evidence that the lattice mode of the 147 cm -1 exhibits a soft mode behavior for the α-β transition in quartz. Copyright © 2012 De Gruyter.
International Turkish Congress on Molecular Spectroscopy (TURCMOS 2015)(13 - 18 Eylül 2015)

Suggestions

Calculation of the Raman Linewidths of Lattice Modes Close to the alpha-beta Transition in Quartz
Lider, Mustafa Cem; Yurtseven, Hasan Hamit (Walter de Gruyter GmbH, 2012-12-01)
The Raman frequencies of the lattice modes (147 cm(-1) and 207 cm(-1)) are analyzed for the alpha-beta transition in quartz according to a power-law formula with the critical exponent by using the experimental data. The temperature dependence of the Raman frequency is associated with the order parameter (polarization P) for this transition in the quartz crystal.
Calculation of the Resonant Frequencies in the Vicinity of the Transition in Quartz
Lider, M. C.; Yurtseven, Hasan Hamit (Springer Science and Business Media LLC, 2015-07-01)
The transition (847 K) in quartz is investigated using the temperature dependence of the resonant frequency and of the lattice constant which are correlated by means of the mode Gruneisen parameter. By determining the mode Gruneisen parameter, the resonant frequencies are predicted in the vicinity of the transition in quartz. This calculation is extended to low temperatures (down to about , and the resonant frequencies are predicted at low temperatures using the lattice parameter data for quartz. Prediction...
Analysis of the Raman frequencies of a lattice mode in NH4Cl close to the tricritical and second order phase transitions
Yurtseven, Hasan Hamit (Elsevier BV, 2006-4)
We analyze here our observed Raman frequencies of the nu(5) (174 cm(-1)) mode in NH4Cl close to its tricritical (P = 1.6 kbar) and the second order (P = 2.8 kbar) phase transitions. The critical behavior of the frequency shifts 1/nu (partial derivative nu/partial derivative T)(P) for this optical mode is described by a power-law with the critical exponent a. Our values of a = 0.01 (T < T-C) and a = 0.11 (T > T-C) for P = 1.6 kbar in NH4Cl are close to the values of 0.066 (=1/16) below T-C and 0.125 (=1/8) a...
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...
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...
Citation Formats
H. H. Yurtseven, “Calculation of the soft mode frequency for the alpha beta transition in quartz,” presented at the International Turkish Congress on Molecular Spectroscopy (TURCMOS 2015)(13 - 18 Eylül 2015), 2015, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/78874.