Effect of heat treatments on the luminescence properties of Zn2SiO4:Mn2+ phosphors prepared by glycothermal methods

Manganese-doped Zn2SiO4 phosphors with different crystal structures and morphologies were synthesized by glycothermal reactions of zinc acetate dihydrate and manganese(II) acetate tetrahydrate with tetraethyl orthosilicate in various glycols at 315 degrees C. The reactions in 1,3-propanediol and 1,4-butanediol yielded alpha-Zn2SiO4:Mn2+, whereas the reactions in ethylene glycol and 1,5-pentanediol yielded beta-Zn2SiO4:Mn2+ and ZnO, respectively. The samples obtained in 1,4-butanediol and 1,3-propanediol emitted green light (522 nm), and the sample prepared in 1,4-butanediol showed a higher emission intensity. The photoluminescence intensity of the Zn1.96Mn0.04SiO4 phosphor prepared by a glycothermal reaction in 1,4-butanediol and subsequently calcined at 1100 degrees C was twice as high as that of the sample synthesized by a conventional solid-state reaction. The high emission efficiency was obtained because the highly homogeneous distribution of Mn2+ in the alpha-Zn2SiO4 host synthesized by the glycothermal reaction was maintained during calcination treatment in air. (C) 2011 Elsevier B.V. All rights reserved.