Calculation of the specific heat close to the first-order and second-order phase transitions in ammonium halides

Date

2000-10-01

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

182
views

0
downloads

This study presents our calculation of the specific heat C-v1 under the prediction of an Ising model. For this calculation we used our observed Raman frequencies for the l'5LO (177 cm(-1)) mode of NH4Br, the v(5)TO (144 cm(-1)) and v(1)TA (93 cm(-1)) modes of NH4Cl close to the first-order phase transitions (P = 0). We also calculate the specific heat Cvi using our observed Raman frequencies for the v(1)TA (93 cm(-1)) mode of NH4Cl close to the second-order phase transition (P = 2.8 kbar) in this crystalline system.

Subject Keywords

Raman, Phase transitions, Ammonium halides

URI

https://hdl.handle.net/11511/56390

Journal

JOURNAL OF MOLECULAR STRUCTURE

DOI

https://doi.org/10.1016/s0022-2860(00)00570-6

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

Calculation of the specific heat close to the multicritical and second order phase regions in ND4Cl Yurtseven, Hasan Hamit (Springer Science and Business Media LLC, 2007-12-01) We calculated the specific heat C-V of ND4Cl under the prediction of an Ising model presented here. Our calculated C (V) agrees with the experimental C (P) data for the multicritical (P = 0.1 MPa) and second order (P = 150 MPa) phase regions in this crystalline system. This agreement is particularly good above T (C) (congruent to 250 K)for the multicritical regime and below T (C) (congruent to 261 K) for the second order phase transition in ND4Cl. This shows that the observed behaviour of ND4Cl can be well ...
Analysis of the frequency shifts close to the second order phase transition in NH4Cl Yurtseven, Hasan Hamit (2001-03-01) In this study we analyzed observed Raman data for the frequencies of the disorder-induced modes of v(7) (93 cm(-1)) and vs (144 cm(-1)) in the second order phase region of NH4Cl (P = 2.8 kbar). By means of a power-law formula describing the critical behaviour of the frequency shifts 1/v(partial derivativev/partial derivativeT)p for those phonon modes studied, we extract the critical exponent value of a = 0.25, which can also describe the critical behaviour of the specific hear Cp close to the second order p...
Calculation of the specific heat for the II-III and II-IV phase transitions in NH4Br Yurtseven, Hasan Hamit (2001-12-01) The specific heat C-VI is calculated in this study using the prediction of an Ising model for the II-IV phase transition at 0.05 GPa and for the IMV phase transition at the pressures of 0.19, 0.99 and 2.1 GPa close to TC for the NH4Br crystal. The values of the critical exponent for the specific heat of NH4Br which we determine from our analysis, are close to the predicted values of 1/16 (T < T-C) and 1/8 (T > T-C) obtained from the 3d Ising model. Our calculated specific heat C-VI agrees well with the expe...
Calculation of the Raman frequencies as a function of temperature in phase I of benzene Tari, O.; Yurtseven, Hasan Hamit (2013-06-01) This study gives our calculation of the Raman frequencies of the lattice modes A (A(1g)), B (A(g)B(2g)) and C (B1gB3g) as a function of temperature at constant pressures of 0, 1.4 and 3.05 GPa for the solid phase I of benzene. The Raman frequencies of those lattice modes are calculated using the volume data from the literature through the mode Gruneisen parameters for the solid phase I of this molecular crystal. It is shown here that the Raman frequencies of the lattice modes studied decrease with increasin...
Calculation of a generalised smectic–hexatic phase diagram in liquid crystals Yurtseven, Hasan Hamit (Informa UK Limited, 2012-5) This study gives a generalised smectic-hexatic phase diagram calculated by the Landau mean field theory. Our calculated phase line equations are fitted to the experimental phase lines, which represent first-order transition for the liquid crystals studied here. The temperature-and concentration-dependent phase lines calculated in this study describe the observed T-X phase diagram for the smectic-hexatic transitions. This indicates that the method of calculating the phase line equations from the mean field t...

Citation Formats

H. H. Yurtseven, “Calculation of the specific heat close to the first-order and second-order phase transitions in ammonium halides,” JOURNAL OF MOLECULAR STRUCTURE, pp. 267–279, 2000, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/56390.