luminescence in the concentrated phosphor

Luminescent silicate core–shell nanoparticles: Synthesis, functionalization, optical, and structural properties

“…The quantum efficiency of photoluminescence was estimated with the help of the method described in Ref. [41] and based on the measurement of the exciting light reflected from the sample and the emitted light in an integrating sphere with a fiber-coupled fluorometer. The highest values, between 20% and 30%, were measured in samples doped with 5 mol% Mn.…”

Synthesis and photoluminescence characteristics of (Sr, Ca)3B2O6:Eu for application in white light-emitting diodes

“…When y is higher than this critical point, both intensities go down with further increment of Eu 2 þ concentration (y). This may be attributed to the increased probability of energy transfer, which leads to concentration quenching among the Eu 2 þ ions with the increase of Eu 2 þ concentration [30]. As a conclusion, the highest luminescence intensity is perceived when the contents of Eu 2 þ ion dopant (y) and Ca 2 þ ion (x) are 0.09 and 1.7, respectively.…”

“…Furthermore the peak at 370 nm is slightly enhanced compared to that at 325 nm, implying the existence of an interaction corresponding to energy transfer between the host lattice and Eu 2 þ ions, which helps the absorption of excitation at around 370 nm. The emission peak centered at 540 nm is ascribed to the 4f 6 5d 1 -4f 7 transition of Eu 2 þ ions [30]. It is worth noting that the peak intensities of both excitation and emission spectra show a trend of increase with the increment of Eu 2 þ concentration (y), and reach a peak value at y¼0.09.…”

“…Compared with that of Sr 2.898 Eu 0.102 B 2 O 6 , the luminescence intensity of SCB:0.09Eu is more than two times higher under the excitation of 370 nm; meanwhile, the emission band of SCB:0.09Eu is broadened by approximately 25 nm with the center shifted by about 24 nm towards green region. This might result from the nephelauxetic effect originated from a higher-energy 4f 6 5d 1 band with an increased Ca 2 þ substituting concentration in the host lattice [30]. Fig.…”

“…2(b)). The shift could be ascribed to the electronegativity difference between Sr 2 þ (0.95) and Ca 2 þ (1.0), which might cause a stronger covalency of the host lattice with the involvement of more Ca 2 þ ions and consequently result in a shift in energy level by affecting the crystal field in matrix [30]. The above investigation indicates that the luminescence property of Sr 3À xÀ y Ca x Eu y B 2 O 6 can be effectively adjusted in the wavelength range from 522 to 564 nm, which is of importance as a potential phosphor.…”