Photoluminescent properties of Eu-doped MAl2Si2O8 aluminosilicates phosphors

The possibility to codoped MAl2Si2O8 (MASO, M = Ca, Sr) aluminosilicates by both Eu2+ and Eu3+ via high temperature solid-state reactions are demonstrated. The concentration of Eu2+ at the expense of Eu3+ cations is privileged via the codoping with higher valence state ions. For BaAl2Si2O8, it appears difficult to stabilize Eu3+ because of difference in radius between the Eu3+ and Ba2+ cations even prepared in pure oxygen atmosphere. The only Eu2+ doped MASO needs to be prepared in reducing atmosphere and exhibit a bluish-white luminescence centred at similar to 425, 404 and 440 nm due to the allowed 4f(6)5d(1)-> 4f(7)(S-8(7/2)) radiative transition for M from Ca to Ba. The irregular evolution of the emission wavelengths going from Ca to Ba could be assigned to a modification of the local chemical environment of Eu2+. For MASO (M = Ca, Sr) compositions, the strongest 4f-4f emission peaks originated from Eu3+ located at similar to 611 nm are attributed to the D-5(0)-> F-7(2) transition and can be sensitized by energy transfer from Eu2+. These lead to the addition of red contribution to the bluish one observed for only Eu2+-doped materials. We expected to take benefit of these observations to generate new phosphors in the future with a control of the CIE (x, y) parameters and to tune white emission from cold to warm. (C) 2018 Elsevier B.V. All rights reserved.