Open AccessРасчет динамики решетки кристаллов RFe-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=- в квазигармоническом приближении
Author(s) -
М.С. Павловский,
Н.Д. Андрюшин
Publication year - 2019
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2019.11.48407.486
Subject(s) - phonon , brillouin zone , lattice (music) , soft modes , phase boundary , phase transition , condensed matter physics , materials science , phase (matter) , chemistry , physics , optoelectronics , organic chemistry , acoustics , dielectric , ferroelectricity
The lattice dynamic calculations and calculation of temperature dependence of the vibrational frequencies in the quasi-harmonic approximation were carried out for RFe3(BO3)4 crystals (R = Pr, Nd, Tb, Dy, Ho) in high temperature phase R32. It was obtained that in the boundary point Λ of Brillouin zone the frequency of instable vibrational mode, which associated with structural phase transition R32 -> P3121, change intensely with temperature in TbFe3(BO3)4, DyFe3(BO3)4 and HoFe3(BO3)4 crystals. The frequency of “soft” mode stabilizes with temperature increasing and takes a real value. Significant changes in phonon spectra, including in the boundary point Λ, in PrFe3(BO3)4 and NdFe3(BO3)4 crystals with temperature increasing were not observed.