The dynamics of the photoluminescence of Pr3+ in mixed lanthanum yttrium oxyorthosilicate hosts

Abstract Praseodymium (Pr 3+ ) doped mixed lanthanum yttrium oxyorthosilicate (LaYSiO 5 ) powder phosphors were synthesized using urea-assisted combustion method. The molar ratio of La:Y were varied in the following manner: La 2-x Y x SiO 5 ( x  = 0, 0.5, 1, 1.5, 2), were x  = 0 is pure La 2 SiO 5 , x  = 2 is pure Y 2 SiO 5 and x  = 0.5, 1, and 1.5 are the admixtures of the two compounds. The X-ray diffractometer results showed that the La 2 SiO 5 and Y 2 SiO 5 crystalized in their pure monoclinic phases, while their admixtures are both present in the same phase. The Burstein–Moss (BM) shift was used to explain the increase observed in the band gap after doping. The influence of the host crystal field on the branching ratios of the photoluminescence emission intensities of the 3 P 0 and 1 D 2 energy levels of Pr 3+ were studied. The electronic transition from the 3 P 0 transition dominated the emission spectra when x  = 0, while the 1 D 2 electronic transition dominated when x  = 2. The variation in the branching ratios of the 3 P 0 and 1 D 2 emission with the change in the molar ratio of La:Y could be due to 3 P 0  →  1 D 2 non-radiative transitions, which increased with the crystal field of the host as the value of x increased (i.e., as the molar ratio of Y increases). Furthermore, it was shown that the 3 P 0 emission lines emerged from Pr 3+ ions occupying La1 and Y1 sites of La 2 SiO 5 and Y 2 SiO 5 respectively, while the 1 D 2 emission lines emerged from Pr 3+ ions occupying La2 and Y2 sites. The decay curve showed three lifetime components from both 3 P 0 and 1 D 2 emission lines, with the 1 D 2 lines having higher lifetimes in all cases.