The effect of Sm-doping on optical properties of LaB6 nanoparticles

Nanocrystalline particles of LaB6, SmB6 and Sm-doped LaB6 have been prepared by a solid-state reaction in order to investigate the optical properties of ternary rare-earth hexaborides. The sizes of prepared nanoparticles range from dozens to more than 200 nm, as confirmed by XRD, SEM and TEM examinations. The optical property concerning the absorption spectra was tested with ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectrum. All samples exhibit high absorbance in NIR range and UV range. The increase of Sm-doping amount shifts the position of minimum absorptance value of LaB6 to the long-wave direction. Density functional theory (DFT) is employed to interpret the optical properties of Sm-doped LaB6, and results indicate that Sm 4f states change the DOS at near Fermi surface of LaB6 after Sm doping and the reduced number of conduction electrons results into the change of absorption spectra.