Influence of the Nd3+ ions content on the FTIR and the visible up-conversion luminescence properties of nano-structure BaTiO3, prepared by sol–gel technique A b s t r a c t The nano-structure BaTiO3 (BT) powder doped with different concentrations of Nd3+ ions were annealed at 750 ◦C for 1 h to form nano-structure tetragonal phase of BT powder. The structure properties studied using XRD and FTIR methods. Sensitized up-conversion luminescence observed under excitation of 808nm diode laser, suggesting that the Nd3+ ions-doped BT might be an ideal up-conversion material for infrared excitation. The influence of increasing the concentration of the Nd3+ ions on the luminescence intensity investigated using laser diode. The up-conversion mechanisms in the doped system will be discussed by analyzing the energy level structures of the Nd3+ ions. © 2009 Elsevier B.V. All rights reserved.