Temperature dependence of the mode Gruneisen parameter in the vicinity of the lambda-transition point in NH4Cl

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).
JOURNAL OF THE INDIAN CHEMICAL SOCIETY

Suggestions

Temperature dependence of the Raman frequencies and bandwidths close to phase transitions in ammonium halides
Yurtseven, Hasan Hamit (2001-09-01)
In this study, we give the temperature dependence of our observed frequencies and bandwidths for the Raman optical modes in the ammonium halides close to the phase transitions of the first order (NH4 Br), tricritical (NH4Cl) and second order (NH4Cl). Using the predictions of an [sing pseudospin-phonon coupled model, which considers interactions between two spin and two phonons, our observed Raman data have been interpreted qualitatively. Our results show that an Ising model considered here can explain the o...
Temperature dependence of the Raman bandwidths and intensities of a lattice mode near the tricritical and second order phase transitions in NH4Cl
Karacali, H; Yurtseven, Hasan Hamit (2006-01-11)
We calculate here the temperature dependence of the damping constant using the expressions derived from the Matsushita's theory and the temperature dependence of the order parameter from the molecular field theory for the tricritical (1.5 kbar) and second order (2.8 kbar) phase transitions in NH4Cl. Our calculations are performed for the nu(5) (174 cm(-1)) Raman mode of NH4Cl for the pressures studied. Predictions for the damping constant are in good agreement with our observed Raman bandwidths of this latt...
Temperature dependence of the damping constant and the order parameter close to the lambda phase transitions in ammonium halides
Yurtseven, Hasan Hamit (Elsevier BV, 2006-10-01)
This study gives our calculation for the damping constant, using the expressions derived for an Ising pseudospin-phonon coupled system in the ammonium halides (NH4Cl and NH4Br). For this calculation of the damping constant, we use the temperature dependence of the order parameter calculated from the molecular field theory. We predict here the damping constants for the v(5) (174 cm(-1)) and v(5) (177 cm(-1)) Raman modes of NH4Cl and NH4Br, respectively, below T-lambda and compare them with our observed bandw...
Temperature and pressure dependence of the mode Gruneisen parameters close to the melting point in hexagonal ice
Karacali, H.; Yurtseven, Hasan Hamit (Elsevier BV, 2007-02-01)
We reexamine the Pippard relations in this study by relating the specific heat C-P to the Raman frequency shifts 1/v(partial derivative v/partial derivative T)(P) and the thermal expansivity alpha(p) to the 1/v(partial derivative v/partial derivative P)(T), when the mode Gruneisen parameter depends on the temperature and pressure close to the melting point in hexagonal ice. From linear relations between them, the values of the slope dP/dT are deduced in this crystal.
Pressure dependence of the Raman frequency calculated from the volume data close to the ferroelectric-paraelectric transition in PbTiO3
Yurtseven, Hasan Hamit (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. Variatio...
Citation Formats
H. Karacali and H. H. Yurtseven, “Temperature dependence of the mode Gruneisen parameter in the vicinity of the lambda-transition point in NH4Cl,” JOURNAL OF THE INDIAN CHEMICAL SOCIETY, pp. 1097–1102, 2006, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/54423.