Nanocrystallization of ferroelectric lithium niobate in LiNbO3-SiO2 glasses

Transparent glasses in the (100-x)LiNbO₃-xSiO₂ system where 20 ≤ × ≤ 35, were produced by conventional melt-quenching technique. The quenched samples were amorphous as proved by X-ray diffraction (XRD) technique. Annealing of the quenched samples at temperatures ranging from 580 to 975 °C resulted in the precipitation of lithium niobate nano-crystals. Scanning electron microscopy (SEM) showed the presence of randomly oriented LiNbO₃ nano-crystals dispersed in a continuous glass matrix. The relative dielectric constant (ε_r) was in the range of 80 to 180 and increased with increasing LiNbO₃ concentration. The glass ceramic samples annealed at temperatures up to 600 °C are fully transparent.