Upconversion emissions in ZnNb2O6:Ho3+/Yb3+ ceramics

• The strong upconversion fluorescence is obtained with a few rare earth ions doped.
• Energy back transfers (EBT) from Ho3+ to Yb3+ are observed.
• Competition (linear and UC) involved in upconversion process.
• ZnNb2O6 ceramics is one of the potential upconversion host materials.

ZnNb2O6:Ho3+/Yb3+ ceramics with different concentrations of Ho3+ ions are prepared by the high temperature solid state method. Under the excitation of 980 nm laser, the strong green emission and red emission bands are observed and attributed to Ho3+:5S2, 5F4→5I8 and 5F5→5I8 transitions, respectively. The intensities of green emission and red emission are decreased with the increasing concentration of Ho3+. The pump dependence and upconversion mechanism are studied. The green and red emissions are two-photon processes at 980 nm excitation.