Nonlinear-optic and ferroelectric behavior of lithium borate-strontium bismuth tantalate glass-ceramic composite

Transparent glasses in the system (100-x) Li2B4O7-xSrBi(2)Ta(2)O(9) (0 less than or equal tox less than or equal to 20) were fabricated via a splat-qu enching technique. The glassy nature of the as-quenched samples was establi shed by differential thermal analyses. X-ray powder diffraction and transmi ssion electron microscopic studies confirmed the amorphous nature of the as -quenched and crystallinity (40 nm) in the heat-treated (glass-ceramic) sam ples. The dielectric constant (epsilon (r)) of the glass-ceramic composite (x=20, heat treated at 773 K/8 h) was in between that of the parent host gl ass (Li2B4O7) and strontium bismuth tantalate ceramics in the frequency ran ge 100 Hz-40 MHz at 300 K. These exhibited intense second-harmonic generati on and a ferroelectric hysteritic behavior (P vs E loops) at 300 K. The coe rcive field (E-c) and the remnant polarization (P-r) were 1053 V/cm and 0.4 83 muC/cm(2), respectively. (C) 2001 American Institute of Physics.