Experimental and theoretical study on structural and electronic properties of LaPO4:Ln3+ (Ln = Sm, Gd and Tb)

In this paper, LaPO4:Ln3+ (Ln = Sm, Gd and Tb) have been successfully prepared by typical hydrothermal method and investigated the changes caused by doping different rare earth ions. The phase composition, absorption edge and fluorescence property have been characterized by XRD, UV-Vis diffused reflectance spectrum and photoluminescence spectroscopy, respectively. We constructed doped molecular models and calculated the lattice parameters, band structure and states density under density functional theory. The experimental and theoretical results indicated that 4f orbitals of doping other rare earth ions introduced impurity energy levels in forbidden band of LaPO4 and increased absorption edges and narrowed band gaps. With the atomic number of doped ions increasing, the electrons on 4f orbital occupied higher energy level around Fermi level. Nevertheless, Gd3+ presented the exception on account of its half-filled-shell effect.