Multi-site occupancies and photoluminescence characteristics in developed Eu2+-activated Ba5SiO4Cl6 bifunctional platform: Towards manufacturable optical thermometer and indoor illumination

Eu2+-activated Ba5SiO4Cl6 phosphors with blue and green emissions were synthesized by a solid-state reaction route in a reduction atmosphere. The obtained crystal structure and photoluminescent properties indicated that three various Ba2+ ions sites were partially occupied by the Eu2+ ions. The optimal doping content for Eu2+ ions in the Ba5SiO4Cl6 system was 5 mol%. The electric dipole-dipole interaction was attributed to the involved concentration quenching effect. The thermal resistance performance was identified by using the temperature-dependent emission spectra. Importantly, the internal quantum efficiency of the established final products reached up to 50.8%. Through utilizing the diverse sensitivities of blue and green emissions from Eu2+ ions to the temperature, a neoteric optical thermometer with a high absolute and relative sensor sensitivity of 0.031 K-1 and 0.87% K-1, respectively, at 498 K was achieved. By integrating the resultant cyan phosphors, commercial CaAlSiN3:Eu2+ red phosphors and a near-ultraviolet chip, the warm white light-emitting diodes with admirable colorific properties were integrated and manufactured. The complementary results elaborate that the Eu2+-activated Ba5SiO4Cl6 phosphors are bifunctional platforms for both optical thermometer and indoor illumination. (C) 2020 Elsevier B.V. All rights reserved.