Hr. Xia et al., Structure and the nonlinearity of lithium triborate studied by Raman and infrared reflectivity spectroscopy, J MATER RES, 16(12), 2001, pp. 3464-3470
Raman and infrared measurements of the LiB3O5 (LBO) crystals were completed
. The experimental results shown here are more and stronger Raman lines and
infrared absorption peaks. which implies that the external vibrations of t
he trigonal (BO3)(3-) and tetrahedral (BO4)(5-) ions, especially the former
, in the six-membered boron-oxygen rings at the low wave number are strong
and the internal vibrations of the (BO4)(5-) ions above 200 cm(-1) are stro
nger than those of the (BO3)(3-) ions if compared with the Raman spectra of
BaB2O4 crystals. These are caused due to the slope and distortions of the
B3O7 rings and their BO3 and BO4 units in LBO, which change the structural
rigidity of the crystals. intensify the long-range electrostatic force and
short-range molecular force, and shorten the ultraviolet absorption edge.