Synthesis and Photoluminescence Properties of Sm~(3+)-doped Ca_(10)(PO_4)_6(OH)_2 Nanowire

摘要

The Sm~(3+)-doped Ca_(10)(PO_4)_6(OH)_2 nanowires are synthesized by hydrothermal method. X-ray diffraction confirmed that the nanowires are made of the hexagonal Ca_(10)(PO_4)_6(OH)_2. Scanning electron microscope and transmission electron microscope analysis show that the lengths of the nanowires are approximately 5 urn, and their diameters are around 100 nm, and the aspect (length/diameter) ratio is about 50. The room temperature photoluminescence (PL) spectra of Sm~(3+)-doped Ca_(10)(PO_4)_6(OH)_2 nanowires doped with different Sm~(3+) concentration under 405 nm excitation has been investigated. It is found that there are three main sharp emissions peaks at near 569, 604, and 649 nm. The three emissions are due to the f-f forbidden transitions of the 4f electrons of Sm~(3+), corresponding to ~4G_(5/2)->~6H_(5/2) (569 nm), ~6H_(7/2)(604 nm), and ~6H_(9/2)(649 nm), respectively. In addition, concentration quenching is also observed. It is found that the Sm~(3+) ~4G_(5/2)-> ~6H_(7/2)(604 nm) emission intensity of Sm~(3+)-doped Ca_(10)(PO_4)_6(OH)_2 nanowires significantly increases with the increase of Sm~(3+) concentration, and shows a maximum when Sm~(3+) doping content is 0.5%. If Sm~(3+) concentration continues to increase, namely more than 0.5%, the Sm~(3+) ~4G_(5/2)->~6H_(7/2) emission intensity decreases.