Correlation between ultrabroadband near‐infrared emission and Yb 3+ /Ni 2+ dopants distribution in highly transparent germanate glass‐ceramics containing zinc gallogermanate nanospinels

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 (Yb 3+ ) and bivalent nickel (Ni 2+ ) in a highly transparent germanate glass‐ceramic containing thermally grown Zn 1+ x Ga 2−2 x Ge x O 4 (0 ≤ x ≤ 1) nanospinels, is revealed by an analytical transmission electron microscope. The elemental mapping and linescan analysis confirm that both Yb 3+ and Ni 2+ accumulate preferentially in the germanium‐substituted ZnGa 2 O 4 nanospinels embedded in the glass. The influence of glass crystallization on the electric transition properties of Yb 3+ is presented. An enhanced ultrabroadband near infrared emission of Ni 2+ is observed as a result of efficient energy transfer from Yb 3+ to Ni 2+ accumulated in the nanocrystals. Discussions are given to account for the detailed mechanisms of the efficient energy transfer occurring between the dopants.