Facile obtainment of luminescent glass-ceramics by direct firing of a preceramic polymer and oxide fillers

Rare-earth (RE) doped glass-ceramics represent very interesting luminescent materials. The thermal annealing of the glass precursor causes the controlled precipitation of several crystalline phases, in which RE may be variously distributed, also with different oxidation states, e.g. Eu2+ and Eu3+. The present investigation demonstrates the feasibility of preparation of RE-doped alumino-boro-silicate glass-ceramics by direct firing in air (at 1000-1200 °C) of a preceramic polymer, filled with nano- and micro-sized particles, as an alternative to glass melting and annealing. In particular BaCO3 or SrCO3 micro-particles, mixed with nano-sized γ-Al2O3, were found to react with amorphous silica, available from the oxidative decomposition of a commercial silicone, yielding a strontium or a barium alumino-silicate phase. Boric acid micro-particles contributed both to the development of a liquid phase upon firing (promoting ionic interdiffusion) and to the formation of a La-borate phase, by interaction with La2O3 micro-particles. The blue and red luminescence of the obtained glass-ceramics is attributed to the incorporation of Eu2+ and Eu3+ ions, from nano-sized Eu2O3 filler, in alumino-silicate and borate phases, respectively.