Preparation and characterization of a novel luminescence nano-sillenite (Bi12SiO20) glass ceramic within Bi2O3–ZnO–SiO2 system

Abstract

Bismuth silicate with sillenite structure (Bi12SiO20) nanophase was prepared via melt–quenching technique in the Bi2O3–ZnO–SiO2 glass system. The effect of replacement ZnO by Bi2O3 was studied. Their thermal behavior showed the change of glass transition temperature (Tg) from 577 °C in the Bi2O3-free glass to 438 °C in ZnO-free glass. In addition, the crystallization temperatures were not only changed from two to one peak, but also decreased from 927 to 476 °C in the same order. According to the heat treatment regimes, willemite, sillenite, tetragonal Bi2O3, cubic Bi2O3 and traces of ZnO were crystallized with different ratios depending on the change in composition and temperature. Sillenite was enhanced with increase heat treatment temperature and/or Bi2O3 additions. Heat treatment at 650 °C/10 h revealed the best regime, where higher degree of crystallization was achieved. The microstructure at 700 ℃/30 min showed nano-scale oriented parallel rod crystals with hexagonal making at their end, whereas clusters of irregular nano-size crystals was appeared at 650 °C/10 h. Transmission spectra of the glasses in UV–Vis–midIR region were increased with Bi2O3 addition reaching 74% in 100B. Photoluminescence properties of both glasses and their corresponding glass–ceramics showed luminescence nature since the blue and green colors were clearly appeared. Calculation of optical bandgap (Eopt) revealed 3.2–2.19 eV with increasing Bi2O3; these values are located in the semiconducting range. The prepared samples can be utilized in electro-optical instruments, also the high transmission in mid-IR nominate it for IR transmitting windows.