Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass

Abstract

Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and formability. However, photoluminescence dynamics of ns2-type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn2+-doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S1-S0 transition and a slower T1-S0 relaxation, and also that the energy difference between T1 and S1 states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S1 and T1 states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors.

Photo- and Radioluminescence of Sn2+ Centers in Alkaline Earth Oxide-Substituted Zinc Phosphate Glass

“…The main lifetime τ 1/e of these relaxation processes is on the order of microsecond, indicating that the observed emission may be attributed to a T 1 -S 0 transition. (1,15) Although these emission decay curves are similar, the decay constants of these glasses are slightly different. Table 1 shows the decay constants of these glasses.…”

“…It has been reported that the Sn 2+ emission peak shifted toward lower photon energy as time elapsed after UV irradiations. (15,16) Considering the PL spectral shape and the PL decay constant, this assumption about the local coordination state of Sn 2+ can be explained without contradiction. The shortened lifetime is considered to be correlated to the aggregation of Sn 2+ species, which is suggested in optical absorption spectra.…”

“…Recently, our group has focused on a RE-free amorphous phosphor using ns 2 -type cations. (11)(12)(13)(14)(15)(16)(17)(18)(19) Because an ns 2 emission center possesses an electron in the outermost shell in both the ground state (ns 2 ) and the excited state (ns 1 np 1 ), these types of emission centers are strongly affected by the coordination state. Although we have reported scintillation properties of the ns 2 -center-containing oxide glasses, (18,19) their efficiency is insufficient for industrial application.…”

Controllable photoluminescence by melting-process temperature in SnO-containing glass

“…3(a)]. 8), 15) In addition, no variation in the spectra was observed as a function of excitation photonenergy. On the other hand, in the glasses processed above 1100°C (i.e., SZB1200 to SZB1500), the shoulder/band appeared additionally at ³2.02.5 eV, which is lower than the broad (blue) PLband [Figs.…”

“…SnO-containing glass has absorbed much attention because the glass possess a large quantum-yield (QY) for visible blue-PL caused by T 1 S 0 relaxation based on s 15) and consequently SnO-containing glass is regarded as a possible candidate for RE-free phosphor and scintillator material. 8), 16) In addition, glass in ZnOB 2 O 3 system, which consists of a typical strong former, is frequently studied from optical/spectroscopic point of view.…”