Boiaryntseva I. Radiation induced processes in the dielectric hosts M1-хRхF2+х (M2+=Cа, Sr, Ba, R3+=Ce, Pr, x=0.35)

This thesis is devoted to the comprehensive study of the crystal structure influence on the radiative relaxation of the electronic excitations and radiation defects formation in the M1-xRxF2+x (M2+=Ca, Sr, Ba, R3+=Ce, Pr, х=0.35) solid solutions using absorption, luminescent and thermoluminescent techniques. Modification of the energetic transitions in M0.65R0.35F2.35 (М2+=Ca, Sr, Ba, R3+=Ce, Pr) reflects the structure peculiarities of the fluorite solid solutions depending on the type of the alkaline-earth cation in the Ca-> Sr-> Ba row. The increase of RF3 concentration in МF2 host results in formation of R3+-containing clusters. The local environment of R3+ in clusters is different from that in basic components MF2:R and RF3. The latter causes changes in splitting parameters and centroid position of the excited 5d state of R3+ ions, leading to the shift in electronic transitions energies of rare-earth ions in the solid solution in comparison with doped MF2:R crystals. The models of emission centers in M1-хRхF2+х (M2+=Cа, Sr, Ba, R3+=Ce, Pr, x=0.35) have been proposed - R3+ ions incorporated into different defect clusters. The structure and composition of the clusters depends on the type of М2+ and R3+ ions. The mechanisms of energy transfer to Ce3+ and Pr3+ ions in the solid solutions under ionizing radiation and the processes of the radiation-induced defects formation have been studied.