Structural changes and self-activated photoluminescence in reductively annealed Sr3AlO4F
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Date
2015-08-01
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Abstract
White light emission of self-activated photoluminescence (PL) in Sr3AlO4F under 254 nm light is only observed after annealing in a reducing atmosphere of 5%H2/95%Ar. High-resolution neutron powder diffraction reveals that the FSr6 octahedrons and AlO4 tetrahedrons in this anti-perovskite structure are closer packed in reduced than in air-annealed samples which show no PL. Careful analysis of temperature-dependent neutron powder diffraction data establishes smaller isotropic displacement parameters for Sr(1) and O in Sr3AlO4F annealed in a reducing atmosphere indicating that the denser packing of the polyhedral sub-units leads to a slightly deeper potential for the Sr(1) and O atoms. Both the air- and reductively-annealed samples have identical thermal expansion within the temperature range between 3 and 350 K. The Debye temperatures were calculated using the atomic displacement parameters and show no significant differences between the air and reductively annealed samples making the Debye temperature a bad proxy for self-activated PL. © 2015 Elsevier Inc.
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Keywords
Neutron diffraction, Photoluminescence, Atomic displacements, Annealing, Thermal expansion, Debye temperature
Citation
Green, R., Avdeev, M., & Vogt, T. (2015). Structural changes and self-activated photoluminescence in reductively annealed Sr3AlO4F. Journal of Solid State Chemistry, 228, 1-8. doi:10.1016/j.jssc.2015.04.017