Self-reduction Synthesis And Photoluminescent Properties Of Eu³⁺-Eu²⁺ Doped Aluminate And Silicates Phosphors

In this paper,Eu²⁺-Eu³⁺doped aluminate and silicate phosphors were prepared by high temperature self-reduction method in air condition.The appropriate reaction conditions were confirmed and the microstructure of samples were modulated by changing the Si and Mg²⁺concentration in matrix.The role of microstructure changing in self-reduction process was well analyzed and the connection between Si,Mg²⁺concentration and emission color,intensity was discussed.Finally,the tunable color was achieved by modulating microstructure.?1?The appropriate reaction conditions of Eu³⁺self-reduction in aluminate matrix was 1300 ?,10 h,the molar ratios of Eu to alkaline-earth metal ions were2%;The characteristic emission of Eu²⁺in Eu-doped aluminate phosphors were observed except Mg Al₂O₄;Based on this result,the structure and photoluminescent properties of MAl₂Si_x O_2x+4?M=Mg,Ca,Sr,Ba;x=0-2?influenced by Si O₂concentration were fruther studied.The results showed:The composition of the samples changing gradually with the increasing x value;Except x=0 and 2,other samples were consisted by mixtures.However,there was no obvious effect on morphologies of samples with the change of x value.;Moreover,Si O₂ could effectively changed the matrix microstructure which led to the apparent change of the emission and excitation spectra of Eu³⁺/Eu²⁺with the increased of x alue.Meanwhile,the existence of Eu²⁺was also confirmed by EPR spectra.?2?Eu-doped M_2-x Mg_x Si O₄?M=Ca,Sr,Ba;x=0-2?were prepared by self-reduction method,the effect of Mg²⁺concentration in structure and photoluminescent properties were studied in this system.The results indicated that the composition of the samples changed continuously with the increased of x value.Except x=0 and 2,other samples were consisted of mixtures.Moreover,the surface of samples was prilled,caused by the added Mg²⁺.The matrix microstructure changing caused by Mg²⁺,which vastly affected the emission spectra and excitation spectra of Eu³⁺/Eu²⁺;In addition,the existance of Eu²⁺was confirmed by comparing the samples prepared in air and reducing atmosphere.It can be found that the coordination number of occupied sites was related to the stabilitu of Eu²⁺.?3?Eu-doped M_3-x Mg_x Si₂O₇?M=Ca,Sr,Ba;x=0-3?were prepared by self-reduction method,the effect of Mg²⁺concentration in structure and photoluminescent properties were studied in this system.The results indicated that the composition of the samples changing gradually with the increasing x value;Except x=3,most of samples were consisted of mixtures.The rising Mg²⁺concentration caused conglutination and surface of sample developed to villous M_2-x Mg_x Si O₄;The matrix microstructure changing caused by Mg²⁺which vastly affected the emission spectra and excitation spectra of Eu³⁺/Eu²⁺;In addition,the existance of Eu²⁺was confirmed by comparing the samples prepared in air and reducing atmosphere.Eu²⁺can replaced many sites in matrix,and different Eu²⁺sites expressed different emission locations,which can effectively regulate the emission color.But only a few sites which met the special conditions can exist stably in air.