Analysis of energy transfer processes in Yb3+-Tb3+ co-doped, low-silica calcium aluminosilicate glasses

Abstract

Energy transfer processes in Yb3+-Tb3+ co-doped, low-silica calcium aluminosilicate glasses were analyzed. Luminescence and time-resolved measurements were used to study upconversion processes, such as Yb-Tb cooperative sensitization, Yb-Yb cooperative luminescence, and Yb-Tb cross relaxation. The quantum cross relaxation efficiency was evaluated as a function on the Yb3+ concentration, and the maximum estimated value was approximately 51%. In addition, the intensity of the upconversion luminescence from the Tb3+:5D4 level decreased by two orders of magnitude comparing the value at room temperature with that at 123 K. As a consequence, Yb-Yb cooperative luminescence around 500 nm became comparable with the intensity of upconversion from the Tb3+:5D4 level. Furthermore, a dependence of the upconversion kinetics luminescence on temperature was observed. The upconversion rise time was constant and equal to 65 μs for temperatures between 296 to 473 K and decreased from 65 to 19 μs, without variation in the decay part, when the temperature was lowered from 296 to 123 K. These results were explained by a phonon-assisted cooperative sensitization process for the population of the Tb3+:5D4 level.

Luminescence of SiO2 and GeO2 crystals with rutile structure. Comparison with α-quartz crystals and relevant glasses (Review Article)

“…[13]). Removal of OH group due to absorption of a photon activates the luminescence center [13]. Different distances between a luminescence center and a separated OH group could modulate population on the excited state, variating decay kinetics.…”

“…Normally, an OH group that interacting with a luminescence center provides luminescence quenching effect in the case of many centers (see e.g. [13]). Removal of OH group due to absorption of a photon activates the luminescence center [13].…”

Resonant excited state absorption and relaxation mechanisms in Tb^3+-doped calcium aluminosilicate glasses: an investigation by thermal mirror spectroscopy

“…Indeed, the sensitization of Tb 3 ions can be achieved through sensitizer ions in codoped glasses, favoring strong emission in the visible region. The spectroscopy of Yb 3 ∕Tb 3 codoped glass materials has been thoroughly investigated [1,[3][4][5]. However, the ESA leads the system to a major heat loss mechanism by populating levels within the 4f 7 5d electron configuration with potential for nonradiative deexcitation.…”

“…Emission was obtained under 325 nm excitation. Details of the measurement conditions are described in [3]. The main electron transitions are labeled.…”

“…Resonant ESA cross sections are found to be more than three orders of magnitude higher than the ground state absorption cross section. The fluorescence quantum efficiency of the 5 D 4 → 7 F j radiative transition is close to unity, and for the 5 D 3 → 7 F j transition it decreases with Tb 3 concentration.The LSCAS:Tb 3 samples were prepared as described in [3,[6][7][8]. To remove OH − , the samples are melted under vacuum conditions at 1650°C.…”