Czochralski Growth and Optical Properties οf $(Lu_{x}Gd_{1-x})_2SiO_5$ Solid Solution Crystals Single Doped with $Sm^{3+}$ and $~Dy^{3+}$

Solid solution crystals $(Lu_{x}Gd_{1-x})_2SiO_5$ single doped with $Sm^{3+}$ and $Dy^{3+}$ were grown by the Czochralski method. Segregation coefficients Lu/Gd, melting temperatures and structures of solid solution crystals were determined for 0.15 ≤ x ≤ 0.8. It was found that for x ≥ 0.17 the crystals belong to the monoclinic system within a space group C2/c and their melting temperature diminishes monotonously from 1990C to 1780C when x decreases from 0.8 to 0.15. Disparity of ionic radii of $Lu^{3+}$ and $Gd^{3+}$ induces structural disorder that brings about an inhomogeneous broadening of spectral lines in absorption and emission spectra of incorporated luminescent $Sm^{3+}$ and $Dy^{3+}$ ions. Optical properties of obtained crystals were determined based on results of measurement of absorption and emission spectra and luminescence decay curves. Spectroscopic investigation revealed that $Sm^{3+}$ doped crystals show intense emission distributed in the visible-near infrared region with the most intense band centred at 605 nm and characterized by a branching ratio of 0.43. Emission spectrum of $Dy^{3+}$ doped crystals is dominated by a band centred at 575 nm and characterized by a branching ratio of 0.58. It has been concluded that the systems under study are potential laser materials able to generate visible emission upon GaN/InGaN laser diode pumping.