Optical, electrical properties and crystallization kinetics of KNbO3 nanocrystal phase formed in potassium borate glass

The kinetic parameters and optical and electrical properties of [40B2O3–30K2O–30Nb2O5] (mol%) glass sample were investigated. The DTA results of glass sample under study display two crystallization exothermic peaks (Tp1 and Tp2) corresponding to or in proportion to the formation of potassium niobate in cubic and transformed to tetragonal structure phases when glass sample was heat-treated at temperatures greater than the second crystallization temperature Tp2. The structure of crystalline phase KNbO3 changes with the increase of temperature as cubic when glass sample was heat-treated at 530 and 620 °C (Tp1 and Tp2) and changed to the tetragonal phase when heat-treated at 730 °C (higher crystallization temperature). The optical band gap (Eg) of the glass sample is equal to 2.7 eV. Measurements of the dielectric constant and dielectric loss as a function of frequency (100 Hz–100 kHz) and temperature (310–800 K) indicate two relaxations at temperature range.