The Effects Of Cation Exchange On Alkaline-earth Metal Alumino-silicate Phosphors For White Leds

Due to its energy savings, positive environment effects, long service time, white light emitting diodes are described as a new generation of solid-state lighting devices. Among the three methods of white LED realization, the wavelength conversion type of single tube core is the main mainstream technology, more common type include blue emitting chips matched with YAG phosphors and near ultraviolet chips matched with tricolored phosphorescent powder. In recent years it has developed near-UV chip and single-phased full-color emitting phosphor which matched with W-LED. Due to its low cost, good color stability and excellent process reproducibility, it has become a research emphasis of new illumination light source. Eu²⁺ activated silicate phosphor becomes a researching focus for its good thermal and chemical stabilities, simple synthesis technology and cheap & available raw material.Eu²⁺ adopted MAl₂Si₂O₈ (M=Ca, Sr, Ba) phosphor were prepared by traditional solid state method. And by means of researching the relationship between phase composition and crystal structure, and luminescence properties, the quantitative and half-quantitative relations between the compositions, crystal structure and luminescence properties of Eu²⁺ activated alkaline earth aluminosilicate were obtained. The exploration of inherent law has provided scientific reference for obtaining high performance and white light-emitting materials.Firstly, the influence of some aspects on the crystal constitution and luminescence performance of Eu²⁺-activited anorthite has been investigated, such as the substitution of part of feldspar cation for Sr²⁺, Ba²⁺, Mg²⁺ ions. The analysis of crystal structure and luminescence performance shows that Sr²⁺ ions can completely replace Ca²⁺ ions to form a continuous solid solution. The lattice parameter of samples and emission spectra have a linear relationship with the concentration of Sr²⁺ substitution in the range 0.1～0.9 mol/mol, however, Ba²⁺, Mg²⁺ can only form a part of the solid solution. When with Mg²⁺, Sr²⁺, Ba²⁺ ions combinations of pairs of ion-exchange, continuous solid solution can be formed within a certain range, in which lattice parameters and emission spectra also displayed regular variation.And then the influence of some aspects on the crystal constitution and luminescence performance of Eu²⁺-activited anorthite has been investigated, such as the substitution of parts of feldspar cation for Ba²⁺, Mg²⁺ ions. The analysis results of phase composition, crystal structure and luminescence properties show that Ba²⁺ ions can completely replace Sr²⁺ ions to form a continuous solid solution. The lattice parameters of samples and emission spectra of peaks are also present linear variation with Ba²⁺ ions content. When with Ca²⁺, Ba²⁺, Mg²⁺ ions combinations of pairs of ion-exchange, the results show that these ions, which in strontium feldspar solid, has a greater solid solution range ,in which the cell parameters and the luminescence spectra of these phosphors also showed regular change.