Tetragonal phase BaTiO3:Eu nanocrystals were successfully synthesized using a hydrothermal method and a subsequent calcination treatment. The structures and morphologies of nanocrystals were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The photoluminescence properties of BaTiO3:Eu were investigated in detail. Under 398 nm excitation, the emissions from Eu2+ and Eu3+ ions were observed, indicating that Eu2+ and Eu3+ ions coexisted in BaTiO3:Eu nanocrystals. Especially, the emission band of Eu2+ from BaTiO3:Eu was observed to broaden with increasing Eu concentration. When the Eu concentration was 0.5 mol%, the D-5(0)-> F-7(0) and D-5(1)-> F-7(0) emissions were observed. In addition, under 537 nm excitation, the emission intensity increased with increasing Eu concentration. (C )2014 Elsevier Ltd. All rights reserved.