Flux Exploration, Growth, and Optical Spectroscopic Properties of Large Size LaBSiO₅ and Eu³⁺-Substituted LaBSiO₅ Crystals

Abstract

This article reports the flux composition optimization, crystal growth, and optical spectroscopic properties of LaBSiO5 and Eu3+-substituted LaBSiO5 crystals. The mixture design technology was successfully applied in the crystal growth area for the first time. By the direction of mixture design method, the composition of a complex flux comprising LaBO3, SiO2, and Li2MoO4 was optimized and used for growth of LaBSiO5 crystals. A large size of Eu3+-substituted LaBSiO5 crystal with dimension of 12 × 10 × 8 mm3 has been prepared by top-seeded solution growth method. As far as we know, it is the first report that active ion-substituted LaBSiO5 bulk crystal was obtained from an environmentally friendly flux without fluorides. The optical spectroscopy and electronic transition properties of Eu3+-substituted LaBSiO5 crystals are studied thoroughly by analyzing the excitation and emission spectra and luminescence decay curves. The luminescence of Eu3+ ions are characteristic of intense red light emission corresponding to transitions of 5D0 → 7F1 and 5D0 → 7F2. Meanwhile, the splitting of emission bands mentioned above is apparent because of the lower symmetry of lattice sites where the active ion locates. Furthermore, the symmetry properties of the lattice sites where Eu3+ ions locate are investigated by using Judd–Ofelt theory. The value of intensity parameters of Eu3+-substituted LaBSiO5 ranges from 4.19 to 4.89 when the Eu3+ concentration varies.