15min:

ALEXANDER BARABASH, T. GAVRILKO, A. PETROSYAN, G. PUCHKOVSKAYA AND A. ROSHIN, Institute of Physics, National Academy of Sciences of Ukraine, 46, Prosp. Nauki, 252022 Kiev, Ukraine.

The lattice dynamics of the pseudo-binary system \bsys has been investigated by means of the IR and Raman spectroscopies and the NQR technique. The spectral changes, observed in the 2600~-~400~\cm region, indicate the formation of variable "intermolecular" hydrogen bonds O-H\trpO in the system between the quasi molecular halogenate groups IO₃^-, HIO₃ and H(IO₃)₂^-. By the analysis of low-frequency Raman spectra of the mixed crystals \mix with varying the concentration x in the range from 0 to 1, the critical x values of HIO₃ content were evaluated at which the hydrogen bonds of different strength are formed and the different crystal structure of the binary system is observed. Thus for the concentration range 0~-~0.22 the IR absorption spectra show wide and weak O-H stretching bands. That concentration range corresponds to \alpha-modification LiIO₃ crystal doped by protons (C₆⁶ space group). Within the intermediate concentration range 0.06~3 and 2LiIO₃·HIO₃ (with unknown crystal structure) exist as it follows from the NQR data. For concentrations x>~0.35 the vibrational spectra of the system correspond to Li-doped orthorhombic \alpha-HIO₃ crystal. From the NQR and Raman data the amorphous ("glass") phase was detected in the concentration range 0.22~-~0.35. Our results help to solve some contradictions concerning the binary system structure obtained by different experimental methods.