Processes of Molecular Relaxation in Binary Crystalline Systems KNO3–KClO4, KNO3–KNO2, and K2CO3–K2SO4

Abstract

The processes of molecular relaxation in binary crystalline systems KNO₃–KClO₄, KNO₃–KNO₂, and K₂CO₃–K₂SO₄ are studied via differential thermal analysis and Raman spectroscopy. It is found that the relaxation time of the vibrations ν₁(A) of anions NO^-₃ and CO^2-₃ in systems KNO₃–KClO₄, KNO₃–KNO₂, and K₂CO₃–K₂SO₄ is less than that in KNO₃ and K₂CO₃, respectively. It is shown that the increased rate of relaxation is explained by an additional relaxation mechanism presented in the system. This mechanism is associated with the excitation of vibrations of anions ClO^-₄, NO^-₂, and SO^2-₄ and the lattice phonons that emerge. It is found that this relaxation mechanism requires correspondence of the frequency difference of these vibrations to the region of sufficiently high density of states of the phonon spectrum.