Structural and dielectric characterization of LiNbO3 nano-size powders obtained by Pechini method

Abstract

Lithium niobate is an artificially synthesized material with wide technological applications, due to its numerous physical properties, such as: ferroelectricity, birefringence and large pyroelectric, piezoelectric, non-linear, acousto-optic, electro-optic and photo-elastic coefficients. It also exhibits very strong bulk photovoltaic and photo refractive effects. In the present work, LiNbO3 powders were prepared by the Pechini (sol–gel) method. The heat-treatment of the base amorphous powders, at 450 °C promotes the formation of LiNbO3 crystalline phase. The electrical characterization, in function of the heat-treatment time, shows that the dc conductivity depends on the quantity of crystalline phase, which increases with the increase of heat-treatment time. The sample treated for 96 h shows a dielectric constant value of ~35, at low frequencies. A dielectric relaxation phenomenon independent of the temperature of measurement was detected in the samples treated at 48 and 96 h, shifting to higher frequencies with the increase of the heat-treatment time.