The presence of different oxidation states of cations in optical hosts on the base of Co:SrLaGa3O7

Abstract Absorption, electron spin resonance (ESR) and RBS spectra were analyzed with the aim to define of oxidation states and sites of cobalt ions in gehlenite structure of SrLaGa3O7 single crystal. It was stated that cobalt 2+ substitute octahedral sites, which is rather not expected result. ESR measurements have given values of g-factor for Co2+ ion equal to g∥=2.26±0.04, g⊥=4.7±0.2. 3+ state of Co2+ ion in SrLaGa3O7 lattice one can obtain by irradiation it with γ-rays, electrons, protons or annealing at oxidizing atmosphere. We observed 5T2–5E Co3+ transition band peaked at about 1200 nm. We observed also that color centers, which appeared after the irradiations, shift the short-wave absorption edge towards the longer wavelengths by a few hundreds nm. The changes are attributed to the lattice Ga2+ centers which are formed according to the reaction Ga3++e−→Ga2+ with a spin of S=1/2, g∥=1.9838(5) and g⊥=2.0453(5). Co-doping with vanadium reveals in higher radiation hardness of Co:SrLaGa3O7 crystal.