Selective Laser Spectroscopy of the Bixbyite-Type Yttrium Scandate Doped by Rare-Earth Ions

Yttrium scandate crystals doped by Nd(3+) and Tm(3+) ions have been successfully grown in the form of fibers using the laser-heated pedestal growth (LHPG) technique. The selective laser spectroscopy methods have identified and distinguished three distinct types of optically active centers associated with Nd(3+) and Tm(3+) ions. The substitution of Y(3+) and Sc(3+) for rare-earth ions in the C(2) structural site leads to the formation of two distinct basic long-time centers. In Nd(3+):YScO(3), another type of center (a short-lifetime one) is formed known as the Nd(3+)–Nd(3+) aggregate pair. This center arises from the substitution of Y(3+) or Sc(3+) for Nd(3+) cation in the adjacent MO(6) polyhedra that share an edge. In Tm(3+):YScO(3), the third optical center is formed as a result of the substitution of Y(3+) or Sc(3+) for Tm(3+) in the MO(6) octahedra with the C(3i) site symmetry. The fluorescence decay lifetimes of Nd(3+) and Tm(3+) ions in the YScO(3) crystal structure have been accurately measured and estimated. A Stark level diagram illustrating the splitting of (4)F(3/2), (4)I(11/2), and (4)I(9/2) multiplets of Nd(3+) ions has been constructed to show features of the active optical centers with the C(2) site symmetry.