Specific heat calculated from the Raman frequency shifts close to the gimel-phase transition in NH4Br

Date

2003-01-01

Author

Yurtseven, Hasan Hamit

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

160
views

0
downloads

We calculated the specific heat C-VI close to the lambda-phase transition in NH4Br on the basis of predictions of the Ising model. We have used our observed Raman frequencies of the nu(5) (134 cm(-1)) lattice mode to extract the critical exponent for the specific heat. The C-VI values calculated by us with this exponent value agree with the measured C-P data reported in the literature. This agreement is particularly good above T-lambda. This indicates that the observed behaviour of NH4Br can be satisfactorily explained close to the lambda-phase transition in this crystal.

Subject Keywords

Physical and Theoretical Chemistry, Mechanics of Materials, Condensed Matter Physics

URI

https://hdl.handle.net/11511/44555

Journal

HIGH TEMPERATURES-HIGH PRESSURES

DOI

https://doi.org/10.1068/htjr070

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

Critical Behaviour of the Heat Capacity Near the alpha-beta Phase Transition in Quartz Yurtseven, Hasan Hamit (Walter de Gruyter GmbH, 2013-04-01) The alpha-beta transition ( T-Q = 578 degrees C) is studied in quartz by analyzing the experimental heat capacity C-p data taken from the literature, using a power-law formula. Values of the critical exponent alpha for C-p are extracted below and above T-Q, which describe the alpha-beta transition as a second order transition in quartz. The alpha values obtained here are compared with the predictions of the theoretical models.
Calculation of the Specific Heat Close to Phase Transition in S-triazine KURT, MUSTAFA; Yurtseven, Hasan Hamit (Walter de Gruyter GmbH, 2009-01-01) The specific heat C-V as a function of temperature has been calculated using the quasi-harmonic and mean field approximation for s-triazine close to the transition temperature (T-C=198 K). Using the parameters for the shear strain angle (order parameter) fitted to the observed Raman frequencies of the four bands, the specific heat C-V is calculated from the free energy of s-triazine.
Raman Study of Solid Nitrogen in the beta Phase and Close to the Melting Line Iseri, E. Cetinbas; Yurtseven, Hasan Hamit (Walter de Gruyter GmbH, 2013-02-01) This study gives the Raman frequencies calculated as functions of temperature and pressure for the lattice modes in the solid beta phase and close to the melting line (beta-fluid transition). The experimental volume data from the literature is used to calculate the Raman frequencies for the molecular nitrogen system. Some observed Raman frequencies are also used as the initial data to perform our calculations given here.
Frequency shifts of the disorder-induced modes close to the tricritical phase transition in NH4Cl Yurtseven, Hasan Hamit (Old City Publishing, Inc, 2003-01-01) We have studied the Raman frequencies of the disorder-induced modes of v, (93 cm(-1)) and v(5) (144 cm(-1)) close to the tricritical phase transition in NH4Cl (P 1.6 kbar, T. 257 K). Using our observed Raman data for these phonon modes, we have obtained the value of the exponent a approximate to 0.3 for the frequency shifts, which can describe the critical behaviour of the thermal expansivity a, and also of the specific heat Cp. Our exponent value can be compared with the value of 0.1 predicted by the 3d Is...
Theoretical investigation of quercetin and its radical isomers Erkoc, E; Erkoc, F; Keskin, N (Elsevier BV, 2003-08-01) The structural and electronic properties of quercetin and its five radical isomers have been investigated theoretically by performing semi-empirical molecular orbital theory calculations. The geometry of the systems have been optimized and the electronic properties of the systems considered have been calculated by semi-empirical self-consistend-field molecular orbital theory at the level AM1 within UHF formalism in their ground state. Conclusions have been drawn by comparing with experimental results.

Citation Formats

H. H. Yurtseven, “Specific heat calculated from the Raman frequency shifts close to the gimel-phase transition in NH4Br,” HIGH TEMPERATURES-HIGH PRESSURES, pp. 321–327, 2003, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/44555.