Luminescence properties and determination of optimal RE3+ (Sm3+, Tb3+ and Dy3+) doping levels in the KYP2O7 host lattice obtained by combustion synthesis

Abstract

The β-KYP₂O₇ powders doped with Sm³⁺, Tb³⁺ and Dy³⁺ were obtained using a one-step urea-assisted combustion method. Their structural properties were characterized by X-ray diffraction (XRD) whereas spectroscopic properties like excitation, emission and luminescence kinetics were investigated at room temperature. β-KYP₂O₇ doped with Sm³⁺ and Dy³⁺ showed concentration quenching above 2 mol% of dopants whereas Tb³⁺ containing materials could be doped with higher concentrations. The main mechanisms of concentration quenching were identified as dipole–dipole for Sm³⁺ and Dy³⁺. Both dopants due to the abundant energy levels are strongly prone to quenching due to the non-radiative CR process whose efficiency strongly increases with the concentration of optically active ions. In the case of Tb³⁺ emission from both ⁵D₃ and ⁵D₄ levels was recorded. The ⁵D₃ level vastly depopulates due to the CR process upon increase of the Tb³⁺ content whereas the slight ⁵D₄ emission remains stable up to 5 mol%.