VIBRATIONAL SPECRTA OF SINGLE CRYSTAL Li2B4O7

Abstract

Polarized Raman spectra of single crystal Li2B4O7 have been measured in the wavenum-ber shift range of 50-3000cm-1 at room temperature. The infrared absorption spectrum of Li2B4O7 has also been measured in the range of 200-4000cm-1 for powder samples dispersed in the pressed KBr disks. Based upon the experimental results of LO-TO splitting, the effective charge and mode strength of polar modes are calculated. A comparison of the structure and B-O stretching vibration frequency of various borate species suggests comparatively high nonlinear optical efficiency of Li2B4O7 crystals.