Photoluminescence in Fe$^{3+}$ ion doped barium titanate nanoparticles

Fe$^{3+}$ ion doped barium titanate (BT) nanopowders were synthesized by the sol gel route. The average size of tetragonal bariun titanate (t-BT) powders lies in the range 16–40 nm. The specimens show ultraviolet (UV) emission (peak at 376 nm) along with emission in violet, blue, green and yellow color. The blue band (peak at 452 nm) is seen to grow significantly with annealing temperature. This band arises due to Ti$^{3+}$ defects which are stabilized by Fe$^{3+}$ ions in BT specimens. The samples show two distinct Electron Paramagnetic Resonance (EPR) bands of $g$-value around 4.11 and 1.98, which originated from Fe$^{3+}$ ions and Ti$^{3+}$ defects respectively. A correlation between the photoluminescence (PL) and EPR band intensity, grown from same species, was found.