Spectral-luminescence properties of ZrO$_2$–Sc$_2$O$_3$–Tb$_2$O$_3$ crystals

Crystals of the concentration series ZrO$_2$–(8–10) mol.% Sc$_2$O$_3$–(1–2) mol.% Tb$_2$O$_3$ were grown by the method of directional crystallization of the melt from a cold container. Analysis of the spectral-luminescence characteristics of these crystals after growth and after annealing processing in a vacuum revealed the presence of both Tb$^{3+}$ and Tb$^{4+}$ ions in them. In crystals ZrO$_2$–(8–10) mol.% Sc$_2$O$_3$–(1–2) mol.% Tb$_2$O$_3$, the presence of a process of non-radiative energy transfer from Tb$^{4+}$ ions to Tb$^{3+}$ ions was revealed.