Up-conversion luminescence of Er2Mo4O15 under 980 and 1550 nm excitation†
Abstract
Y2−xErxMo4O15 (x = 0.04, 0.08, 0.16, 0.32, 0.64, 2.0) phosphors were synthesised at 700 °C through a solid-state reaction method. The samples were characterised by XRD and emission spectra analysis. Y2−xErxMo4O15 samples showed a strong green emission (2H11/2, 4S3/2 → 4I15/2) and a weak red emission (4F9/2 → 4I15/2) under 1550 and 980 nm excitation. The green emission intensity was enhanced increasing the Er3+ ion doping content, whereas the red emission was basically unchanged. Thus, Er2Mo4O15 exhibited an abnormal green up-conversion luminescence without concentration quenching under 1550 and 980 nm excitation. The dominating green up-conversion luminescence was due to the larger adjacent Er3+⋯Er3+ distance caused by the special structure of Er2Mo4O15, which limited the energy-transfer process and cross-relaxation responsible for the red up-conversion emission. Therefore, the up-conversion luminescence mechanism was excited-state absorption under 1550 nm excitation.