The decay model of Eu2+ and Eu2+, Dy3+ substituted SrAl2O4 prepared by high temperature solid phase method

A fluorescence decay model related to SrAl2O4: Eu-0.01(2+) and SrAl2O4: Eu-x(2+), Dy-x(3+) (where x = 0.01-0.04) is proposed in this article. By studying the logarithm decay regularity of rare earth doped SrAl2O4 , linear relation for SrAl2O4: Eu2+ and SrAl2O4: Eu-0.04 (2+), DY0.04 (3+), and quadratic function decay for SrAl2O4: Eu-x(2+) , Dy-x(3+) (where x = 0.01-0.03) are found. These nonexponential decay confirm that lifetime spreads to a distribution - P(tau). The complex crystal field around Eu2+ and sensitive 4f(6)5d(1) configuration make the excitation state energy levels broaden, promoting the formation of the lifetime distribution. By fitting the afterglow decay curves, logarithm distribution function of SrAl2O4: Eu2+ and SrAl2O4: Eu-0.04(2+) presents a linear relation. The deviation from linear distribution function for all the SrAl2O4: Eu-x(2+), Dy-x(3+) samples is very small. The residual ratio of electron in excited state and the number of newly increased excitation electron from traps can direct confirm detrapping process after codoping of Dy.