Excitation dependent site-specific luminescence and structure-optical property correlation of Lu2Sn2O7:Eu3+ nanoparticles

Abstract

Abstract Understanding of structure-property correlation is of paramount importance in designing phosphors which impact the advanced lighting technology. Here, for the first time, we have synthesized La2Sn2O7:Eu3+ (LSOE) nanoparticles (NPs) and investigated their optical properties under host and Eu3+ intra-configurational f-f excitations at 274 and 395 nm, respectively. Under 274 nm excitation, Eu3+ ions are found to localize at both LaO8 and SnO6 polyhedra to an equal extent, which leads to comparable intensity of the forced electric dipole transition (FEDT) and magnetic dipole transition (MDT). Under 395 nm excitation, Eu3+ ions at SnO6 polyhedra is selectively excited, which gives more intense FEDT. Accordingly, the LSOE NPs give orange and red emissions under 274 nm and 395 nm excitations, respectively. The quenching concentration of Eu3+ ions in the LSOE NPs is 5.0 mol% due to multipolar interactions. Maximum asymmetric ratio happens for the LSOE NPs at the doping level of 7.5% due to the largest fraction of Eu3+ ions at SnO6 polyhedra. Reversely, longest lifetime occurs for the LSOE NPs at the doping level of 0.5% owing to enhancing defect density at elevated Eu3+ doping. Point group symmetry of Eu3+ ions is C3 based on Stark splitting determination. Judd-Ofelt analysis suggest that the excitation of the LSOE NPs at 395 nm leads to narrow red emission with lower non-radiative transition and higher internal quantum yield. Our work is expected to excite more luminescence scientists to explore the application potentials of the Lu2Sn2O7 NPs for color-tunable optoelectronics, solid state lighting and bioimaging.