Radiation-stimulated transformations Yb$^{3+}$ $\to$ Yb$^{2+}$ and Yb$^{3+}$ $\to$ Yb$^{3+}$ in single crystals and nanoceramics CaF$_2$ : YbF$_3$

The radiation resistance of CaF$_2$ : YbF$_3$ (3 mol.% YbF$_3$) laser ceramics and a single crystal of similar composition (3.6 mol.% YbF$_3$) exposed to gamma rays in a $^{60}$Co source is studied. The non-irradiated samples have been shown to be similar in spectral characteristics. After the CaF$_2$ : YbF$_3$ crystals and ceramics $\gamma$-irradiation and the following time exposure, along with transformations Yb$^{3+}$ $\to$ Yb$^{2+}$, configurational Yb$^{3+}$ $\to$ Yb$^{3+}$ transitions between different states of Yb$^{3+}$ ions in the structure of samples are carried out, with the participation of interstitial $F_i$ ions.