Luminescence properties of translucent nano- and micro-crystalline LuPO4:Ce3+ films in the 20-700 K range of temperatures

Photoluminescent properties of nano- and micro-crystalline LuPO4:Ce3+ sintered materials were investigated in the temperature range of 20-700 K. It was shown that the nano-powders may be converted into highly translucent layers with good mechanical stability by heat-treatment at 1000 °C. Processing at higher temperatures caused grains growth and formation of a network of voids resulting in an increase of light scattering. Luminescent properties were analyzed in the 20-700 K range of temperatures. Electron-phonon coupling decreased when grains became smaller. As a result, the Stokes shift was smaller in the nano-ceramics (1010 cm−1) than in micro-ceramics (∼1580 cm−1). Energies of the crystal field components of 2F5/2 and 2F7/2, Stokes shift and kinetics of Ce3+ luminescence in the nano- and micro-size material over the 20-700 K range of temperatures were determined. It was shown that LuPO4:Ce does not suffer from thermal quenching up to about 650 K. Nano-ceramics appeared even more resistant to thermal quenching than micro-ceramics showing no indication of decay time shortening up to 700 K.