Photoluminescent Nanocrystals in a Multicomponent Aluminoborosilicate Glass

Abstract

In this study, stable and nonexpensive aluminoborosilicate glasses with different photoluminescence colors were synthesized by doping with Pb(II), Ba(II) and sodium halides. While glasses with NaF and NaCl exhibit no (or very low) luminescence, glasses doped with NaBr and NaI display room-temperature photoluminescence at 435 and 530 nm, respectively. The observed room-temperature photoluminescence is attributed to nanocrystals whose presence is revealed by transmission electron microscopy. The crystalline nature of the particles, which are pointed out as barium-lead halides, is also revealed by anisotropy measurements for Br and I doped samples. Time-resolved luminescence measurements show a second-order kinetics component combined with a first-order nonradiative rate constant. The photoluminescence properties here described are important for the future design of new optical materials or devices based on lead halide nanocrystals.

Phase Diagram, Scalar-Pseudoscalar Meson Behavior and Restoration of Symmetries in (2 + 1) Polyakov-Nambu-Jona-Lasinio Model

“…However, when µ B > 1419 MeV (ρ B > 5.85ρ 0 ) the K − becomes once again a bound state (this behavior was already found in [116,148]). Still as far as the K − is concerned, it was shown in [41,42,47,148] that there are low bound states with quantum numbers of K − that appear below the inferior limit of the Fermi sea continuum of particle-hole excitations being the Fermi see bounded by ω low = (M 2 s + λ 2 u ) 1/2 − µ u and ω up = (M 2 s + λ 2 s ) 1/2 − (M 2 u + λ 2 s ) 1/2 . However, we will not go further in this discussion.…”

“…In [95], the meson masses were calculated by supposing that the pole is near the real axis and the imaginary part of the solution in the argument of Equation (A3) of the Appendix A is neglected. In [47,51,115] only the Γ 2 M contribution coming from (M M − iΓ M /2) was neglected.…”

“…One of the first big achievements of the NJL model was the study of meson properties at finite temperature and density, first in SU(2) sector [33][34][35] then in the (2 + 1)-flavors, where the role of strangeness was taken in consideration [11,[36][37][38][39][40][41][42][43][44]. The chiral symmetry restoration through the point of view of the chiral partners has entered in the agenda.…”

Effects of d0 and s2 cations on optical properties of silicate glasses

“…While all glasses will crystallise over a long enough time frame, '[the] ultimate fate, in the limit of infinite time, is to crystallise' [105], uncontrolled bulk crystallisation tends to produce poorly-performing glass-ceramics, as the devitrification process occurs at random times and locations [182]. However, upon addition of a suitable nucleating agent such as TiO2 [183], ZrO2, halides [184], phosphates [185], or Ag2O [186], the nucleation and subsequent crystallisation occurs at a particular time and location within the network and under the right conditions, allowing careful control of the subsequent glass-ceramic.…”

“…Glass-ceramics have interesting properties that are difficult to achieve with either component. The mechanical [188,189], optical [184,[190][191][192] and electrical [193] properties can be dramatically improved upon partial crystallisation.…”