Calculation of the Ν4 (NH4) IR Mode Frequency and the Damping Constant (FWHM) Close to the Phase Transitions in NH4Zn(HCOO)3 and Nd4Zn(DCOO)3

2018-09-09
Kurt, Arzu
Yurtseven, Hasan Hamit
Kurt, Mustafa
Temperature dependence of the IR frequency and the damping constant (FWHM) of the ν4(1440 cm-1) NH4+and ν4(1084 cm-1) ND4+ modes, are calculated for the metal formate frameworks (MOFs) of NH4Zn(HCOO)3 and ND4Zn(DCOO)3, respectively, by using the experimental data from the literature. By assuming the IR frequency of the ν4 mode as an order parameter, its temperature dependence is calculated close to the phase transition (TC=191 K) in the NH4Zn(HCOO)3 and ND4Zn(DCOO)3 by the molecular field theory. The temperature dependence of the damping constant of the ν4 (NH4+) IR mode is also calculated by means of the pseudospin-phonon coupled (PS) and the energy fluctuation (EF) models for these metal formate frameworks. The damping constant due to both models (PS and EF) is fitted to the observed FWHM data of the ν4 (NH4+) IR mode from the literature at various temperatures close to TC in the MOFs studied.Our results show that the molecular field theory is adequate for the temperature dependence of the IR frequency and also the PS model explains the observed behaviour of the FWHM for the ν4 (NH4+) mode in NH4Zn(HCOO)3 and ND4Zn(DCOO)3
Citation Formats
A. Kurt, H. H. Yurtseven, and M. Kurt, “Calculation of the Ν4 (NH4) IR Mode Frequency and the Damping Constant (FWHM) Close to the Phase Transitions in NH4Zn(HCOO)3 and Nd4Zn(DCOO)3,” presented at the Turkish Physical Society 34th International Physics Congress, (5- 09 Eylül 2018), 2018, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/73238.