Studies on the luminescence properties of europium doped strontium alumino-silicate phosphors by solid state reaction method

The Sr2Al2SiO7:Eu2+ and Sr2Al2SiO7:Eu3+ phosphors were prepared by the traditional high temperature solid state reaction method. The crystal structures of sintered phosphors were gehlenite type structure which belongs to the tetragonal crystallography with space group P42¯1m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\rm P}\bar{42}_{1}{\rm m} $$\end{document}. Thermoluminescence properties of these phosphors were investigated and results were also compared. Under the ultra-violet excitation (345 nm), the Sr2Al2SiO7:Eu2+ phosphor would emit bluish-green (cyan) light, belonging to the broad emission band ascribed to the 4f65d1 → 4f7 transition. The emission spectrum (λex = 395 nm) of Sr2Al2SiO7:Eu3+ phosphor were consisted of two emission peaks at 593 and 613 nm, which were attributed to 5D0 → 7F1 and 5D0 → 7F2 of Eu3+ ions. The strongest excited band at 395 nm can be assigned to 7F0 → 5L6 transition of Eu3+ ions due to the typical f–f transitions within Eu3+ of 4f6 configuration. Commission International de I’Eclairage color coordinates of Sr2Al2SiO7:Eu2+ and Sr2Al2SiO7:Eu3+ phosphors were suitable as bluish-green and orange-red light emitting phosphors respectively. The mechanoluminescence (ML) intensity of Sr2Al2SiO7:Eu2+ and Sr2Al2SiO7:Eu3+ phosphors increase linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the piezo-electrically induced de-trapping model is responsible to produce ML in sintered phosphors.