K_3Gd_3B_4O_(12): a new member of rare-earth orthoborate for luminescent host matrix

摘要

A new member of rare-earth orthoborate K3Gd3B4O12 was prepared by a flux method and structurally characterized by single-crystal structure analysis for the first time. It features a two-dimensional layer structure containing [Gd-8(BO3)(8)] layers parallel to the ab-plane. Gd(3)O-7 groups, B(3)O-3 groups, B(4)O-3 groups and large K+ ions distribute in between the[Gd-8(BO3)(8)] layers, and bond adjacent layers. Theoretical researches by density functional theory (DFT) revealed that the compound K3Gd3B4O12 is an indirect band-gap semiconductor and the optical absorption can be mainly ascribed to OK, OGd and OB charge transfers. Moreover, a series of K3Gd3-x-yB4O12:xTb(3+), yEu(3+) phosphors were prepared, their morphology and tunable multicolour emission properties were studied. Under UV or near-UV excitations the luminescence colours will tune from green through yellow, orange to red by simply adjusting the relative Tb3+ and Eu3+ concentrations.