A1 Refereed original research article in a scientific journal
Abnormal co-doping effect on the red persistent luminescence SrS:Eu2+,RE3+ materials
Authors: Almeida dos Santos Danilo Ormen, Giordano Luidgi, Stock Grein Barbará Miguel Aguirre, Portes Marcelo Cecconi, Santos Pedroso Cassio Cardoso, Teixeira Veronica Carvalho, Lastusaari Mika, Veloso Rodrigues Lucas Carvalho
Publisher: ROYAL SOC CHEMISTRY
Publication year: 2020
Journal: Dalton Transactions
Journal name in source: DALTON TRANSACTIONS
Journal acronym: DALTON T
Volume: 49
Issue: 45
First page : 16386
Last page: 16393
Number of pages: 8
ISSN: 1477-9226
eISSN: 1477-9234
DOI: https://doi.org/10.1039/d0dt01315c
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/51319203
Persistent luminescence materials are a reality in several applications. However, there is still a lack of efficient red-emitting materials. SrS:Eu2+ phosphor is a potential candidate since its strong nephelauxetic effect shifts Eu(2+)4f(6)5d(1) -> 4f(7) to red, and its weak bond between strontium and sulphide, due to the soft base-hard acid character, generates a high number of intrinsic defects. SrS:Eu2+,RE3+ materials were efficiently prepared by two rounds of 22 min microwave-assisted solid-state synthesis. The highly crystalline purity and the material organization at the micro-scale were observed with X-ray powder diffraction and scanning electron microscopy, respectively. X-ray absorption spectroscopy revealed a low amount of Eu2+ compared to Eu3+ due to the efficient Eu2+ photo-oxidation by X-ray irradiation in the high storage capability SrS host matrix. Electron paramagnetic resonance spectra confirmed that at least 50% of Eu2+ ions in the material are photo-oxidized during excitation, reinforcing the previously established mechanisms. The RE2+ energy level positioned very close to or into the conduction band led to an abnormal co-doping effect, with similar effects independent of the co-dopant. The high concentration of intrinsic defects in SrS indicates that the soft-hard pair host is an excellent approach to develop efficient persistent luminescence materials.
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