Calculation of the damping constant and activation energy for raman modes in (NH4)2SO4
Küçük Resim Yok
Tarih
2011
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
World Scientific Publ Co Pte Ltd
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The temperature dependence of the damping constant is calculated for various Raman modes in (NH4)(2)SO4 by the expressions derived from the soft mode hard mode coupling model and the energy fluctuation model. The expressions for the damping constant are fitted to the measured Raman bandwidths and then the activation energies are extracted, which are equal to similar to 0.2 eV for the Raman modes studied. The damping constant of a soft mode is also calculated and the activation energy (similar to 0.1 eV) is deduced in this crystal. Values of the activation energies obtained here, can be compared with the value of k(B)T(C) = 0.02 eV for (NH4)(2)SO4. This indicates that this ferroelectric material undergoes an order disorder transition. It is concluded that the observed behaviour of (NH4)(2)SO4 can be described reasonably by the soft mode hard mode coupling model considered here.
Açıklama
Anahtar Kelimeler
Damping Constant, (NH4)(2)SO4, Ferroelectric Phase
Kaynak
International Journal Of Modern Physics B
WoS Q Değeri
Q4
Scopus Q Değeri
Q3
Cilt
25
Sayı
15
