Tuning and high temperature fluorescence properties of LaPO4:Sm3+ nanophosphors

Abstract

A series of LaPO4:x%Sm3+ nanophosphors were successfully synthesized through a one-step hydrothermal method, where the acidity of the reaction system was meticulously modulated without the addition of any organic compounds. The influence of pH values and Sm3+ doping concentration on the structure, morphology, and luminescent properties of LaPO4:x%Sm3+ was systematically investigated. The composition, structure, morphology, and luminescent properties of the products were characterized and analyzed using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM, EDS), transmission electron microscopy (TEM), and fluorescence spectrophotometry (FL). The results indicate that the acidity of the reaction system effectively influences the morphology and size of the nanophosphors, facilitating the controlled synthesis of nanorod-shaped, nano-spherical, and ellipsoidal phosphors. When the Sm3+ doping concentration is 2 %, the phosphors exhibit maximum luminescent intensity and fluorescence lifetime. The energy transfer between Sm3+ ions in LaPO4:x%Sm3+ is identified as electric dipole-electric dipole interaction, with a critical distance for energy transfer established at 1.593 nm. LaPO4:2%Sm3+ exhibits good thermal stability, characterized by a thermal quenching activation energy of 0.1660 eV. The main outcome of this research, LaPO4:2%Sm3+ phosphor, exhibits significant potential for use in optical sensors, as well as promising applications in solar cells and biological fields.