Synthesis and Upconversion Luminescence of LiY<sub>9</sub>(SiO<sub>4</sub>)<sub>6</sub>O<sub>2</sub> Phosphor Doped with Pr<sup>3+</sup>
Nadiia Rebrova, Patrycja Zdeb, P.J. Dereń
Abstract
High Resolution Image Download MS PowerPoint Slide The increasing demand for ultraviolet light sources in various industries, including security, phototherapy, and sterilization, has spurred research efforts toward discovering new UV phosphors. Herein, we introduce LiY 9 (SiO 4 ) 6 O 2:Pr 3+ as a novel ultraviolet-C (UVC) phosphor, synthesized via the sol–gel technique with varying Pr 3+ concentrations (0, 0.1, 0.5, 1, 1.5, and 2%). For the first time, this study comprehensively describes the emission and excitation spectra, as well as the emission decay kinetics of Pr 3+ ions in LiY 9 (SiO 4 ) 6 O 2 . Two distinct classes of Pr 3+ -emitting centers were identified, denoted as Pr(1) and Pr(2), which replace Y ions at two different lattice sites, 4f and 6h, respectively. Pr 3+ ions at the 4f site exhibit 4f 2 → 4f 2 emission solely, while those at the 6h site emit predominantly in the ultraviolet, 75% of which is in the UVC range. Furthermore, LiY 9 (SiO 4 ) 6 O 2:Pr 3+ excited by laser at a wavelength of 444 nm, both a continuous wave and a pulse, exhibits upconversion emission in the UV region. Upconversion mechanisms were analyzed regarding Pr 3+ concentrations and the excitation regime. Upconversion was found to result from the excited-state absorption. However, for the pulse excitation, a very small fraction of Pr 3+ ions is excited to 4f 1 5d 1 levels involving the energy transfer upconversion mechanism.