Spectroscopic properties of Dy3+ ions in La3Ga5.5Ta0.5O14 single crystal

Abstract Single crystal of La3Ga5.5Ta0.5O14 (LGT) doped with Dy3+ was fabricated by the Czochralski technique and investigated employing methods of optical spectroscopy. Polarized optical absorption spectra and luminescence spectra were recorded at room temperature. Unpolarized absorption and luminescence spectra were recorded at 10 K. Spectra of blue luminescence related to transitions 4I15/2, 4F9/2 → 6H15/2 were recorded at several temperatures in the 300–773 K region. Dy3+ ions have the same symmetry sites in LGT but their spectra show inhomogeneous broadening due to structural disorder of the host and are markedly anisotropic. Results of the Judd-Ofelt treatment made it possible to assess emission cross sections for the 4F9/2 → 6H15/2 blue luminescence and for the 4F9/2 → 6H13/2 yellow luminescence employing Fuchtbauer-Ladenburg formula and reciprocity method. In particular, a spectral distribution of La3Ga5.5Ta0.5O14: Dy3+ σ-polarized luminescence band with an emission cross section σem = 0.51 ·; 10−20 cm2 at 573.5 nm is favorable for a laser operation in the visible. Interpretation of the effect of temperature on the blue emission spectra leads to the conclusion that La3Ga5.5Ta0.5O14: Dy3+ is promising for application as luminescent thermometer.