Reduction Of Eu Ions In Sr₃Al₂O₆

In the luminescence materials excited by making use of the d→f electron transition of rare-earth element, the change of chemical composition of materials often affects the crystalline structure of the matrix, which often causes the shift and shape change of the emission spectrum. Therefore, luminescence materials with desired emission wavelength can be obtained by adjusting the chemical composition of matrix reasonably.The matrix Sr3Al2O6 used in this paper has the superstructure of perovskite. The rare-earth element ions have two alternatives to replace strontium ions because the strontium ions in matrix has two kinds of coordination, and two different kinds of crystal environment can be formed, so then Eu3+ in the Sr3Al2O6 matrix is difficulty to be reduced. In ordinary occasion, it is impossible to realize the effective reduction of Eu3+ in undoped Sr3Al2O6 matrix, and the Sr3Al2O6 fluorescence material excited by Eu3+ will be red.Metal ions are the main reductant for Eu3+ reduction. In the study, we try to dope nonmetal elements into Sr3Al2O6 matrix to reduce Eu3+ effectively. Firstly we determines the better ratio of raw materials and synthetic process parameters for synthesized samples with high temperature solid state method, the X-ray diffraction analysis results show that P can be doped into Sr3Al2O6 matrix which cause the changes of lattice parameter. The ratio of reduced Eu3+ can be controlled by adjusting the amount of (NH4)3PO4·3H2O, and the yellow-green emission Sr3Al2O6:Eu2+ fluorescent materials can be obtained when Eu3+ is reduced fully by adding enough (NH4)3PO4·3H2O.In addition, this paper also investigates the stability of Eu2+ in Sr3Al2O6 matrix, the results indicate that Eu2+ can exist stably and can not be ionized. The amounts of adding Eu and (NH4)3PO4·3H2O have no adverse effects on the stability of Eu2+.Anyhow, the adding of (NH4)3PO4·3H2O in the synthesis process of Sr3Al2O6:Eu2+ can promote the Eu3+ reduction and stable Sr3Al2O6:Eu2+ fluorescent materials can be obtained.