Preparation and photoluminescence properties of Eu3+ doped Li2O–Al2O3–B2O3 glass-ceramics

Promising red emitting Li–Al–B glass (G) and glass-ceramics (GC) Eu3+ doped were prepared with composition 50–0.5xLi2O · 5–0.05xAl2O3 · 45–0.45xB2O3 · xEu2O3 (x = 0, 0.5, 1.0 and 1.5 mol %). Different temperatures (Tg, Tx, Tc1, Tc2, Tm1 and Tm2) were obtained by Simultaneous DTA-TGA (SDT) measurements, obtaining a low on-set temperature, Tx, around 520 °C. LiAlB2O5 and LiBO2 are obtained as crystalline phases, but a new phase, Li3AlB2O6, emerges as Eu3+ increases, resulting in severely decreasing of crystallinity percentage of the GC system. Crystalline phases are identified through X-Ray Diffraction (XRD) and percentage of the amorphous phase is calculated. The Infrared and Raman spectra supports the evidence obtained in XRD measurements. Scanning Electron Microscopy shows different sizes and shapes of particles. Excitation and emission spectra, PLE and PL, respectively, were obtained, as well as time decay and quantum yield around 7.3%. Thermal behavior is analyzed for glass and glass-ceramics through thermal quenching and activation energy. A high thermal stability for GC is obtained with a thermal quenching (TQ1/2) higher than 250 °C, while TQ1/2 is 175 °C for G system. Red emitting color is calculated in the CIE diagram and is supported by visual evidence. The evidence of a distorted europium site in the different crystalline phases suggest the cause of the loss of crystallinity in glass-ceramics systems.