Microwave hydrothermal synthesis and upconversion properties of Yb/Er doped YVO nanoparticles.

Yb and Er doped YVO (Yb/Er:YVO) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb/Er:YVO nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to H, S to I and F to I transitions of Er respectively. The emission intensity is found to depend strongly on the concentration of Yb. The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.