Fluorescence and atomic defect properties of rare earth doped barium titanate

Rare earth doped barium titanate was studied by laser induced fluorescence. Trivalent erbium and europium were used as dopant ions. Rare earth ions primarily entered the crystal with a distant charge compensation, though a small amount were associated with other defects in the crystal. There were thirteen spectroscopically distinct erbium sites characterized and ten distinct europium sites characterized.; The crystals were annealed at 800°C in air and in a mixture of CO and CO₂ gas to cause oxygen vacancies to react with the rare earth ions. They were also annealed at 1250°C in air to allow cation motion so that cation defect reactions with rare earth ions could be studied as well. It was found that some erbium ion sites were stable at lower temperatures, but could only be formed during crystal growth. Some erbium sites also seem to be associations with oxygen vacancies in the crystal. A defect model of barium titanate was also developed to help explain defect reactions.; Europium sites did not show reproducible results with the annealing experiments, but the ionization energy of divalent to trivalent europium ions in a barium titanate host crystal was estimated at 1.1 eV due to a change in the characteristics of the europium sites at about 0.06mol% europium dopant.