K3Gd3B4O12: a new member of rare-earth orthoborate for luminescent host matrix

Abstract

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 [Gd8(BO3)8]∞ layers parallel to the ab-plane. Gd(3)O7 groups, B(3)O3 groups, B(4)O3 groups and large K+ ions distribute in between the[Gd8(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 O→K, O→Gd and O→B charge transfers. Moreover, a series of K3Gd3−x−yB4O12:xTb3+, yEu3+ 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.