Molecular Relaxation in LiNO3–LiClO4 and Li2CO3–Li2SO4 Solid Binary Systems

Abstract

The paper presents spectroscopic combinational scattering investigations of the molecular relaxation in LiNO₃–LiClO₄ and Li₂CO₃–Li₂SO₄ solid binary systems. It is found that the relaxation time for ν₁(A) vibrations of NO₃^– anion in LiNO₃–LiClO₄ system is lower than in LiNO₃ crystal. And the relaxation time for ν₁(A) vibrations of CO₃^2– anion in Li₂CO₃–Li₂SO₄ system is lower than in Li₂CO₃ crystal. The increase in the relaxation time is explained by the additional relaxation mechanism of the excited mode of nitrate and carbon ions which is observed in these systems. This mechanism is linked to the vibrations of other anions (ClO₄^– or SO₄^2–) and a nucleation of the lattice phonon. Experiments show that the additional relaxation mechanism occurs due to the vibration difference which corresponds to the area of rather a high density of states of the phonon spectrum.