Spectroscopic and photoluminescence properties of Ho 3+ doped Ba 0.65Sr 0.35TiO 3 nanocrystals

Abstract

Ho 3+ doped Ba 0.65Sr 0.35TiO 3 (BST) nanocrystals was prepared by sol–gel method. The structural and morphological properties of the nanocrystals were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The absorption spectrum, photoluminescence spectrum and fluorescence time decay curve were measured at room temperature. Based on the Judd–Ofelt (J–O) theory, the J–O intensity parameters Ω t ( t=2, 4, 6) of Ho 3+ doped BST nanocrystals were calculated to be 0.67×10 −20 cm 2, 1.11×10 −20 cm 2 and 1.09×10 −20 cm 2, respectively. The emission probabilities, radiative lifetimes and branching ratios of the different Ho 3+ transitions were also determined. The emission cross sections of the important intermanifold transitions 5F 4 , 5S 2 → 5I 8, 5F 5 → 5I 8 and 5F 4→ 5I 7 have been calculated from the luminescence spectrum. The room temperature fluorescence lifetime of the 5S 2→ 5I 8 transition for Ho 3+ in BST nanocrystals was measured and the radiative quantum efficiency was estimated to be 61.9%.