The Properties of Upconversion Luminescence on YAIO3:Er3+ Nanophosphors with Different Er3+ Concentrations

We report the properties of upconversion luminescence on Yttrium aluminum perovoskite (YAlO3) doped with trivalent erbium at concentrations of 1, 2, 3, 5 and 7 mol%. The samples were synthesized by solvo-thermal reaction method and the XRD patterns conforms that the YAP:Er3+ nanophosphors have orthorhombic phase. Efficient green and red upconversion (UC) emission of YAP:Er3+ nanophosphors was measured under the excitation of 975 nm continuous wave diode laser, and its dynamics and pump power dependence were investigated. As concentration of Er3+ ion increased from 1 to 7 mol%, the red UC emission increased more rapidly. It is attributed to the energy transfer (I-4(11/2) -> I-4(15/2):I-4(13/2) -> F-4(9/2)) and to the cross relaxation (S-4(3/2) -> I-4(9/2):I-4(15/2) -> I-4(13/2)) between Er3+ ions. In this case, the green and red emissions were yielding from quadratic to linear. These conclusions obtained are confirmed by theoretical investigations based on steady-state rate equations.