Analysis of Raman spectra of LiB3O5 single crystals

Polarized Raman spectra of LBO single crystal were recorded in the temperature range 300-870 K. At room temperature, 26A(1), 27A(2), 26B(1) and 26B(2) modes expected from group theoretical analysis are observed by various scattering geometries. Among them, the internal bands are tentatively assigned to vibrations of the BO3 triangle and BO4 tetrahedron in terms of factor group analysis. Based on the temperature dependence of the wavenumbers, the Gruneisen parameters of A(1)(TO), B-1(TO) and B-2(TO) modes are calculated and discussed. No soft modes are observed in the above temperature range, implying that no displacive-type phase transition takes place there. The crystal structure of LBO below 870 K is stable.