Color centers aggregation kinetics in lithium fluoride after gamma irradiation

White‐emitting phosphor Ba2B2O5:Ce3+, Tb3+, Sm3+: Luminescence, energy transfer, and thermal stability

“…As a green‐emitting activator, Tb 3+ can be incorporated into many hosts as the efficient green emission component . As depicted in Figure A, the excitation spectra monitored at 548 nm of BBO: y Tb 3+ contain a broad band centered at 262 nm and many other lines.…”

“…As a green-emitting activator, Tb 3+ can be incorporated into many hosts as the efficient green emission component. 24,25 As depicted in Figure 7A, the excitation spectra monitored at 548 nm of BBO:yTb 3+ contain a broad band centered at 262 nm and many other lines. The former is attributed to the spin-allowed 4f 8 ?4f 7 5d 1 transition, and the latter is the spin-forbidden 4f?4f transition, which can be evaluated according to the following equation: 26,27 E (Ln, A) cm À1 =49340 cm À1 À D(A) + ΔE Ln,Ce .…”

Diffusion and aggregation of subsurface radiation defects in lithium fluoride nanocrystals

“…Below, the value of E Sav = 1.00 eV will be used as the value determined from a larger number of experimental measurements and as more reliable. The activation energy E av for the vacancies diffusion in the bulk of LiF crystals is equal to 0.60 eV [12,13]. The inequality E Sav > E av and the values of the activation energies indicate that the potential barrier separating the fluorine ion in the lat tice site from the vacant site (vacancy) in the subsur face layer is substantially greater than that in the bulk of the crystal.…”

“…The defects in the subsurface layer, unlike the defects in the bulk of the crystal does not diffuse at these temperatures [10]. This fact suggests that the activation energy of the diffusion for these defects in the subsurface layer is significantly higher than in the bulk of the crystal, where it is 1.07 eV [11,12]. The aggregation of defects in subsurface layers, which is provided by the migration of vacancies, opens possibilities for studying the kinetics of aggregation reactions at different temperatures and for determin ing the activation energy of the diffusion for vacancies in the subsurface layers.…”

“…These characteristics for nanocrystals can not be measured using electrical methods, for exam ple, by detecting the electric current provided by the motion of ions in the samples. In this situation, it is promising to use optical methods, in particular, the recording of the kinetics of aggregation defects by the fluorescence or absorption methods [11,12]. In the post radiation period, the aggregation of surface defects was observed in LiF subsurface layers.…”