Shape controllable synthesis and multicolour fluorescence of lanthanide doped Vernier yttrium oxyfluoride

A series of Tb3+ and Eu3+ activated orthorhombic yttrium oxyfluoride, Y7O6F9 (denoted as V-YOF hereafter) phosphors were synthesized through a facile two-step hydrothermal synthesis route followed by heat treatment for the first time. The phase, morphologies, sizes and photoluminescence properties of as-prepared samples were investigated by means of XRD, SEM, and luminescence spectroscopy. A series of characteristic emission originated from the f-f transitions of Eu3+ and Tb3+ can be observed and multicolour emissions from green to yellow and then to red have been achieved in the V-YOF:Tb3+, Eu3+ samples under 378 nm irradiation. The energy transfer process from Tb3+ to Eu3+ was studied and demonstrated to be a quadrupole-quadrupole interaction mechanism. These results show that the V-YOF phosphors have potential applications in field-emission displays.