AbSiO₄ Based Orthosilicate Phosphors And The Investigation On Photoluminescence And Structure Properties

White light emitting diodes（w LEDs） have been applied as the next generation solid state lighting devices and rare earth luminescent materials（phosphors） play a very important role in wLEDs. As we all know, many matrices can act as excellent phosphor hosts, such as silicates, aluminates, borates and nitrides/oxynitrides, and so on. The orthosilicates A2SiO₄（A = Ca, Sr, Ba） phosphors, have drawn much attention owing to their abundant phase transformations, rigid crystal structures, broad excitation/emission bands and tunable optical properties. In this paper, we discuss the investigation on photoluminescence and structure properties of several selected ABSiO₄ based orthosilicate phosphors. The main research content includes:In view of structure modulation and color regulation of ABSiO₄ based orthosilicate phosphors, firstly we have discussed blue-emitting CaSrSiO₄:Ce³⁺,Li+ phosphors, then the effect of substituting Al³⁺ for Si⁴⁺ of CaSrSi1-x AlxO₄:Ce³⁺,Li+ phosphor has been studied. With increasing Al concentration, the increasing distortion of the（Ca1/Sr1/Ce1/Li1）O₁₀ and（Ca2/Sr2/Ce2/Li2）O9 polyhedra result in the emission spectra gradually red shifted. We have also studied the luminescence properties of Lu_xSr_2-x-ySiNxO_4-x:yEu²⁺ phosphors. With increasing [Lu³⁺-N3-] substitution content, the crystal field environment of Eu²⁺ is covalently enhanced also the PL emission shows a red-shift and the emission color can be tuned from yellow green to deep yellow.In view of rare earth codoping and color regulation of ABSiO₄ based orthosilicate phosphors, we have also discussed Ba_1.55Ca_0.45SiO₄:Eu²⁺,Mn²⁺, CaSrSiO₄:Ce³⁺,Li+,Mn²⁺ and Ca_1.65Sr_0.35SiO₄:Ce³⁺,Li+,Eu²⁺ phosphors, studied the photoluminescence properties and energy transfer processes. Firstly, we studied a novel single phased white light phosphor Ba_1.55Ca_0.45SiO₄:Eu²⁺,Mn²⁺, the energy transfer from Eu²⁺ to Mn²⁺ adheres to a quadrupole-quadrupole interaction and the emission color can be tunable from blue to green, white and eventually to yellow by increasing the content of Mn²⁺ ions. Secondly, we synthesized the color-adjustable CaSrSiO₄:Ce³⁺,Li+,Mn²⁺ phosphor, with increasing the content of Mn²⁺, the intensity of Mn²⁺ emission increased and the intensity of Ce³⁺ emission decaeased, the decay time of phosphors was found to decrease and the color adjustable. Lastly,We studied the structure, crystallographic site and tunable luminescence properties of Ca_1.65Sr_0.35SiO₄:Ce³⁺,Li+,Eu²⁺ phosphor. The crystal structure of Ca_1.65Sr_0.35SiO₄ was identified as the αL-Ca2SiO₄ phase and Ce³⁺/Li+ and Eu²⁺ dopants were determined to occupy the specific crystallographic positions of Ca²⁺/Sr²⁺. The emission color under the irradiation of 365 nm can be tuned from blue to green through the energy transfer between Ce³⁺ and Eu²⁺ ions.