Spectroscopy of Eu³⁺ ions in congruent strontium barium niobate crystals

The optical properties of single crystals of strontium barium niobate, grown from the congruently melting composition and doped with different amounts of europium, are investigated. Absorption and emission spectra are measured in the visible and infrared spectral regions at different temperatures. From the spectra, conclusions on the structural sites can be drawn, revealing the major occupations of the B1 and B2 sites, and a minor one of the A2 site. The data are used to calculate crystal-field parameters for the mainly occupied site. A Judd–Ofelt analysis shows that the radiative quantum efficiency is approximately 70%. Furthermore, the influence of europium doping on the phase-transition temperature is determined.