Optical and Dielectric Properties of BaF(2):(Er,Yb) Co-Doped Crystal.

A BaF(2) single crystal co-doped with Er(3)⁺ and Yb(3)⁺ was grown by the vertical Bridgman technique and investigated for its optical and dielectric properties. Judd-Ofelt analysis yielded intensity parameters Ω(2) = 0.59, Ω(4) = 0.38, and Ω(6) = 0.27 (×10(-20) cm(2)), with a quality factor χ = 1.41, indicating strong radiative transitions. Under UV and near-UV excitation, emissions at 321, 405, 518, and 536 nm were observed, with radiative lifetimes ranging from 1.1 to 3.4 ms. A single dielectric relaxation process was identified, with activation energy of 0.58 eV and associated with trigonal NNN dipoles. The NNN dipole concentration was estimated at ~2.5 × 10(18) cm(-3). These results support the suitability of Er(3)⁺,Yb(3)⁺ co-doped BaF(2) crystals for luminescent and dielectric applications in advanced photonic materials.