Structural, electrical properties and photoluminescence analyses of the terbium doped barium titanate

Abstract

Multifunctional materials integrating optical and electric properties into a composite or into a doped single–phase material have attracted much attention from scientists for future optoelectronic devices. In this work, polycrystalline Ba1–xTbxTiO3, x = 0.00, 0.01 and 0.05 materials were synthesized by hydrothermal route and their photoluminescence and dielectric properties were studied. The as–prepared powders showed a microstructure consisting of grains with the shape of cube; and average particle size ranging from 75 nm to 150 nm. The investigated temperature dependence of dielectric permittivity of Ba1–xTbxTiO3 ceramics revealed a decrease of the Curie temperature (Tc) with increasing terbium content, and a more pronounced degree of diffuseness of phase transition. The resistivity at room temperature was discussed in terms of positive temperature coefficient of resistance (PTRC) effect. UV–vis reflectance spectra of Ba1–xTbxTiO3 samples showed a decrease of the band gap energy with the increase of Tb amount, due to the band–gap narrowing effect. The photoluminescence spectra recorded for Tb doped BaTiO3 materials, at 80 K, evidenced the typical f–f luminescence lines of the Tb3+ accompanied the broad luminescence band at about 425 nm due to self–trapped exciton recombination. These results demonstrated that the terbium enhances the dielectric properties and photoluminescence simultaneously, being suitable for electronic applications.