Vacuum-UV excitation and visible luminescence of nano-scale and micro-scale NaLnF4:Pr3+ (Ln=Y, Lu)

Abstract The UV–Vis luminescence of NaLnF 4 :Pr 3+ (Ln = Y, Lu) materials can be efficiently excited by vacuum UV radiation (VUV) such as the 172 nm emission of mercury-free Xe-discharge lamps. In this work, the optical properties of the cubic α -phase and the hexagonal β -phase of NaLnF 4 :Pr 3+ (Ln = Y, Lu) powders are compared regarding particle sizes in the nano- and micrometer regime. Upon VUV excitation, the emission spectra of both crystal phases are found to be dominated by intraconfigurational [Xe]4f 2 –[Xe]4f 2 transitions, which is explained by the chemical properties of the ternary fluorides. Furthermore it is observed that the emission and excitation spectra of nano- and micro-scale powders are very similar, but that the luminescence intensity is affected by the average particle size.