Effect of silver metallic particles on the spectral properties of europium ions in a potassium barium borate glass

Potassium barium borate glasses (KBBO) embedded with europium and/or silver were made by the melt quenching technique. Silver metallic particles were induced by the heat-treatment technique. The average size of the particles is 4 nm. The influence of silver metallic particles (Ag MPs) on the luminescence characteristics of Eu3+-doped glass samples was examined by absorption, emission and excitation spectral measurements after each heat treatment. Under UV excitation Eu3+ emission intensity increased significantly in KBBO:EuAg co-doped glass due to efficient energy transfer and plasmonic coupling between Ag particles and Eu3+ ions. Energy transfer from Ag clusters to Eu3+ was demonstrated experimentally. Samples annealed in a reduced atmosphere revealed the presence of Eu2+ ions in the KBBO glass. The Eu doped sample annealed in a reduced atmosphere glowed bright white under 375 nm laser excitation. Color coordinates, color temperature and color rendering index (CRI) were measured for the glass which indicated that this material is suitable for the development of white light generating phosphor coatings for LED bulbs. The Judd–Ofelt (J–O) intensity parameters, radiative transition probabilities, branching ratios and emission cross-sections were estimated for these glasses. This study has provided valuable insights into the interaction between Ag particles and Eu3+ ions. The data indicates that Eu2+, Eu3+-doped glasses are suitable for the development of optically pumped solid state lasers and nonlinear optical devices.