Crystal structure and optical spectra of Er:NaLa_xYb _9.x(SiO₄)₆O₂ (x=0,3,5,7,9) crystals prepared through a hydrothermal routine

For the first time, nano-scale rods of NaLa_xYb _9-x(SiO₄)₆O₂ (x=1,3,5,7,9) crystals (NLS) activated with Er³⁺ have been synthesized through a mild hydrothermal conditions with subsequent calcination. The as-obtained products were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that the compound has an apatite structure and crystallizes in the hexagonal system, space group P6₃/m. The excitation spectrum and emission spectrum were also emplyed to investigate the optical properties of the nano-rods. The Er³⁺ doped NLS exhibit green/red up-conversion luminescence under excitation with a diode laser at 980 nm.