Synthesis of LaPO₄:Eu Nanostructures Using the Sol−Gel Template Method

Abstract

The sol−gel template synthesis method was used to investigate size-induced changes in luminescence properties of Eu3+-doped LaPO4 materials. Both untemplated bulk powders as well as templated nanotubes ranging in size from 20 to 200 nm were synthesized. These materials were dried at 70 °C or dried and sintered at 650 °C. Powder X-ray diffraction data indicate that the untemplated dried bulk powder is a mix of hexagonal and monazite phases, whereas the dried and sintered bulk powder is a pure monazite phase. When the LaPO4:Eu material is templated, nanotubes are formed that reflect the dimensions of the template membrane. Luminescence data indicate the Eu3+ ion substitutes for the La3+ ion in the LaPO4 host lattice for both the bulk powders and the nanotubes. Notably, as the diameter of the tube decreases, the spectra broaden and the background signal increases significantly. This is likely the result of increased defects in smaller particles that have a larger surface-to-volume ratio.