Multi-site occupancies of Eu2+ in Ca6BaP4O17 and their potential optical thermometric applications

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2019-08, Vol.369, p.376-385
• Main Authors: Zhou, Rongfu, Liu, Chunmeng, Lin, Litian, Huang, Yan, Liang, Hongbin
• Format: Article
• Language: English
• Subjects: Ca6BaP4O17; Energy transfer; Eu2; Luminescence; Thermometry
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.03.073

[Display omitted] •Eu2+ ions occupy Ba2+, Ca2+(1) and Ca2+(2) sites in Ca6BaP4O17 compound.•The energy transfer from EuBa2+ to EuCa2+ is mainly due to dipole-dipole interaction.•The energy migration between donors EuBa2+ is weak even in high doping range.•The emission color is tunable at different doping concentrations and temperatures.•Ca6BaP4O17: Eu2+ materials have potential optical thermometric applications. Single Eu2+ doped Ca6BaP4O17 materials are demonstrated to show potential optical thermometric applications with doping concentration-dependent luminescence and temperature-sensitive luminescence. Eu2+ ions occupy three types of lattice sites based on the results of Rietveld refinements, VUV–UV–vis (vacuum ultraviolet – ultraviolet – visible) luminescence spectra and time-resolved emission spectra. Due to site occupation and energy transfer, the emission color of Eu2+ doped Ca6BaP4O17 materials is tunable with the variation of the doping concentration of Eu2+. Then the energy transfer mechanism is analyzed using Inokuti-Hirayama, Yokota-Tanimoto, and Burshteĭn models, respectively. Because of the different thermal behaviors of Eu2+ luminescence in Ba2+, Ca2+(1) and Ca2+(2) sites, Ca6BaP4O17: Eu2+ phosphors appear obvious emission intensity evolutions with the increase of temperature, accompanying with the change of emission color under excitation at 300 and 400 nm, respectively. It indicates that Eu2+ doped Ca6BaP4O17 phosphors possess temperature sensitive luminescence characteristics. The temperature-dependent ratiometric emission intensity and the temperature recycle measurements verify the possibility of optical thermometric applications of Ca6BaP4O17: Eu2+ phosphors.