Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1520638 | Materials Chemistry and Physics | 2016 | 8 Pages |
Abstract
An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al2O4 (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu2+ 4f 65d1 â 4f7, Eu3+4D0 â 7F, and Dy3+4F9/2 â 6H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv)em, between 5d and 4f of Eu2+ ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f 9/2 â 6h for Dy3+ is merely depend on the transfer of energy from Eu2+ upon excited. Ca-containing phosphor with maximum (hv)em is attributed to the lowest bond length of CaO and highest ionization potential of Ca2+ ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
Chen-Jui Liang, Hao-Yi Siao,