文摘
A new potassium lutetium borate, K3LuB6O12, was synthesized by a flux method and the crystal structure was determined by the single crystal X-ray diffraction. It crystallizes in non-centrosymmetric space group R32 and features a three-dimensional framework that is composed of B5O10, KO6, KO8, LuO6 and (K|Lu)O6 groups. Band structure calculations by the density functional theory method indicate that K3LuB6O12 has direct bond gap of about 2.84 eV. The optical absorption can be mainly ascribed to the charge transitions from the O-2p states to the Lu-6s and Lu-5d states. Moreover, Eu-doped phosphor K3Lu0.95Eu0.05B6O12 was synthesized by a solid-state reaction and its photoluminescence properties were studied. Under near-UV excitation (393 nm), K3Lu0.95Eu0.05B6O12 exhibits an intense red emission centered at around 611 nm with the CIE coordinate of (0.641, 0.357), which can be assigned to the electric dipole 5D0 → 7F2 transition of Eu3+ ions. We think that K3Lu0.95Eu0.05B6O12 may be used as a good red phosphor pumped by near UV light LED chips.