Correlation between ultrabroadband near‐infrared emission and Yb³⁺/Ni²⁺ dopants distribution in highly transparent germanate glass‐ceramics containing zinc gallogermanate nanospinels

Abstract

The photoluminescence properties of dopants are strongly correlated with their distributions in host phosphors, the knowledge of which, however, is not well established yet. In this paper, the distribution of the active dopants, for example, trivalent ytterbium (Yb3+) and bivalent nickel (Ni2+) in a highly transparent germanate glass‐ceramic containing thermally grown Zn1+xGa2−2xGexO4 (0 ≤ x ≤ 1) nanospinels, is revealed by an analytical transmission electron microscope. The elemental mapping and linescan analysis confirm that both Yb3+ and Ni2+ accumulate preferentially in the germanium‐substituted ZnGa2O4 nanospinels embedded in the glass. The influence of glass crystallization on the electric transition properties of Yb3+ is presented. An enhanced ultrabroadband near infrared emission of Ni2+ is observed as a result of efficient energy transfer from Yb3+ to Ni2+ accumulated in the nanocrystals. Discussions are given to account for the detailed mechanisms of the efficient energy transfer occurring between the dopants.

Largest Enhancement of Broadband Near-Infrared Emission of Ni2+ in Transparent Nanoglass Ceramics: Using Nd3+ as a Sensitizer and Yb3+ as an Energy-Transfer Bridge

“…For example, it was 11 recently reported by some of the authors of this article that the efficiency of Yb 3+  Ni 2+ can be as high as ~ 70 % in the identical nano-GCs. [7][8] The discrepancy arises mainly because of the larger energy mismatch in Nd 3+  Ni 2+ (~ 1840 cm -1 ) than in Yb 3+  Ni 2+ (~ cm -1 ).…”

“…5 Since nickel has a highly stable valence state (Ni 2+ ) among the studied TM ions, Ni 2+ doped nano-GCs containing Ga O 3 NCs have proved to be a very promising candidate for tunable NIR light sources. [6][7][8] However, a looming challenge exists as Ni 2+ often suffers from much weaker (by two orders of magnitude) PL than rare earth (RE) ions (e.g, Er 3+ ). The use of sensitizers, e.g., Cr 3+ , Yb 3+ , Bi 3+ , [8][9][10] which have much larger energy harvesting of pump light sources, is an effective strategy to improve the emission gains of Ni 2+ .…”

“…[6][7][8] However, a looming challenge exists as Ni 2+ often suffers from much weaker (by two orders of magnitude) PL than rare earth (RE) ions (e.g, Er 3+ ). The use of sensitizers, e.g., Cr 3+ , Yb 3+ , Bi 3+ , [8][9][10] which have much larger energy harvesting of pump light sources, is an effective strategy to improve the emission gains of Ni 2+ . For example, the integrated emission intensity of Ni 2+ has been enhanced by a factor of 4.4 (4.0) as a result of energy transfer (ET) from Yb 3+ (Bi 3+ ) to Ni 2+ at the 980 nm excitation.…”

“…Finally, the promising Nd 3+ /Yb 3+ /Ni 2+ doping scheme has led to the use of dual-laser pumping as a highly efficient means of generating the greatest enhancement of Ni 2+ emissions in nano-GCs reported to date. [5][6][7][8] Photoluminescence emission, PL decay and time-resolved emission spectra (TRES) were recorded using an FLS980 fluorescence spectrometer (Edinburgh Instruments) equipped with the single photon counting technique. The emission spectra were corrected using the instrumental response.…”

Transition metals as optically active dopants in glass-ceramics

“…sensitizing. 28,29 Cr 3+ ions are also competitive energy sensitizers in RE-based laser solids because the visible and NIR emissions of Cr 3+ significantly overlap with the absorption of RE (Nd 3+ , Tm 3+ ) ions. 26,30 Tb 3+ was also used as an efficient sensitizer for [6] Mn 2+ in ZnAl2O4 NCs embedded in a GC, giving intense red photoemission.…”