Calculation of the specific heat for the II-III and II-IV phase transitions in NH4Br

Date

2001-12-01

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

138
views

0
downloads

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 experimental Cp below TC in the antiferro-ordered (phase III) and ferro-ordered (phase IV) phases of NH4Br. Above T-C (disordered phase II) there occur discrepancies between our calculated C-VI and the observed C-P for NH4Br.

Subject Keywords

Ammonium halides, First order, Lambda, System, NH4CL

URI

https://hdl.handle.net/11511/55364

Journal

Chinese Journal of Physics

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

Specific Heat of NH4Cl and NH4BrxCl1-x Crystals Close to the Ferro-Ordered Phase Yurtseven, Hasan Hamit (2009-04-01) This study gives calculation of the specific heat C-VI of NH4Cl and NH4BrxCl1-x under the Ising model for the transition between the disordered (D) and ferro-ordered O(F) phases in these crystalline systems. Our C-VI values which we calculated for x = 0 and x = 0.04, agree both below and above T-c with the observed C-p data from the literature. Our value of a congruent to 0.1 (T < T-c and T > T-c) is in good agreement with the predicted value of 1/8 (0.125) of a 3D Ising model.
Calculation of the specific heat for ND4Br close to phase transitions Yurtseven, Hasan Hamit (2002-03-01) This study gives our calculation for the specific heat close to the phase transitions from the disordered (phase 11) to the antiferro-ordered (phase 111) and to the ferro-ordered (phase IV) phases in ND4Br. We calculate the specific heat C-VI due to the nearest-neighbour interactions between ND4+. tetrahedra in the ND4Br crystal, by using an Ising model superimposed on an Einstein and/or Debye model which we have developed. Our calculated specific heat C-VI agrees well with the experimental C-p data for the...
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 close to the first-order and second-order phase transitions in ammonium halides Yurtseven, Hasan Hamit (2000-10-01) 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 crystallin...
Calculation of the infrared frequency and the damping constant (full width at half maximum) for metal organic frameworks Kurt, M.; Yurtseven, Hasan Hamit; Kurt, Aygül; Aksoy, S. (IOP Publishing, 2019-06-01) The rho(NH2) infrared (IR) frequencies and the corresponding full width at half maximum (FWHM) values for (CH3)(2)(NH2FeMII)-M-III(HCOO)(6) (DMFeM, M = Ni, Zn, Cu, Fe, and Mg) are analyzed at various temperatures by using the experimental data from the literature. For the analysis of the IR frequencies of the rho(NH2) mode which is associated with the structural phase transitions in those metal structures, the temperature dependence of the mode frequency is assumed as an order parameter and the IR frequenci...

Citation Formats

H. H. Yurtseven, “Calculation of the specific heat for the II-III and II-IV phase transitions in NH4Br,” Chinese Journal of Physics, pp. 349–356, 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/55364.