Reduction mechanism and energy transfer between Eu<sup>3+</sup> and Eu<sup>2+</sup> in Eu-doped materials synthesized in air atmosphere
Shahab Khan, Hongwei Zheng, Huan Jiao, Shahroz Saleem, Zarif Gul, Jehan Y. Al‐Humaidi, Areej Al Bahir, Raed H. Althomali, Arshad Ali, Mohammed M. Rahman
Abstract
Abstract This article critically examines the reduction mechanisms and energy transfer processes between trivalent europium ions (Eu 3+ ) and divalent europium ions (Eu 2+ ) in materials synthesized in an air atmosphere. It also encompasses various materials and conditions, including a critical analysis of the reduction mechanism and energy transfer between Eu 3+ and Eu 2+ in Eu-doped materials. Specific investigations include exploring the reduction process in BaMgSiO 4 :Eu, focusing on factors influencing the reaction. The article also covers low-temperature self-reduction, addressing conditions and mechanisms such as the charge compensation model and laser-induced reduction. Additionally, it explores the influence of charge compensation on luminescent properties, emphasizing enhancements in red emission. Investigations into the role of oxygen vacancies in the reduction of Eu 3+ and their implications on material properties are presented. This article further digs into abnormal reduction processes and the formation of defect centers in Eu 3+ -doped pollucite, proposing a substitution defect model for the self-reduction of europium ions in silicate Ba(Eu)MgSiO 4 phosphors. Unusual reduction phenomena, such as reduction via boiling water in Yb 2 Si 2 O 7 :Eu 3+ phosphors, and reductions in various glass systems, including porous glass, ZnO–B 2 O 3 –P 2 O 5 glasses, aluminoborosilicate glasses, europium-doped Li 2 B 4 O 7 glass, and aluminosilicate oxyfluoride glass (AOG), are also thoroughly examined.