The Study Of Crystal Structure Design And Photoluminescence Properties Of ?Ca,Sr?_2+xLa_8-x?SiO₄?_6-x?PO₄?_xO₂:Eu²⁺ Phosphors

In this study,we prepared a series of apatite phosphors using solid solution design method to meet the research demand of straight white phosphor and establish the relationship between the crystal structure of apatite and the characteristics of photoluminescence spectrum.We have carefully investigated the phase information and the photoluminescence properties,and propose a theory of the relationship between occupancy rate and photoluminescence spectrum.The main results are as follows:?1?The series apatite phosphors Ca_2+xLa_8-x?SiO₄?_6-x?PO₄?_xO₂:0.02Eu²⁺and Ca_5.95-xSr_xLa₄?SiO₄?₂?PO₄?₄O₂:0.05Eu²⁺have been firstly prepared using high temperature solid state method.The variation trends of cell parameter match well with the substitution process of cation.Due to the substitution between cations,the crystal field strength and the energy level splitting shows change,thus,the photoluminescence spectrum shows red-shift or blue-shift phenomenon.The series phosphors display good properties and wide color range,covering the white light region.?2?In the study of Ca_5.95-xSr_xLa₄?SiO₄?₂?PO₄?₄O₂:0.05Eu²⁺,the different electrostatic bond strength of cation site make the occupancy rate of La³⁺in 4f site five times as much as that in 6h site.Therefore,with the increase of Sr²⁺occupancy rate in 6h site,the proportion of the relevant excitation peak shows increase trend,leading the red-shift and much more broader of the spectrum.The series phosphors have been covered on a LED chip to make a series self-made LED lamp,these lamps have good color rendering index?85?and suitable correlated color temperature?4053K-9353K?,the good light quality proves that the series phosphors have great application potential.?3?The green phosphor Ca₆La₄?Si O₄?₂?PO₄?₄O₂:Eu²⁺and yellow phosphor Sr₆La₄?SiO₄?₂?PO₄?₄O₂:xEu²⁺have been synthesized using high temperature solid state method.The shortwave excitation peak in photoluminescence spectrum is corresponding to the Eu²⁺in 4f site,the long-wave excitation peak is corresponding to the Eu²⁺in 6h site.The Ca₆La₄?Si O₄?₂?PO₄?₄O₂:0.01Eu²⁺phosphor has been coated on a LED chip to make a LED lamp.The lamp has good color rendering index?86?,and the correlated color temperature is 4253K.The good light quality proves the Ca₆La₄?Si O₄?₂?PO₄?₄O₂:0.01Eu²⁺phosphor have great application potential.?4?The Eu²⁺doped straight white phosphor has been successfully made by properly adjustment the proportion of blue content Ca₈La₂?PO₄?₆O₂:0.02Eu²⁺and yellow content Sr₆La₄?SiO₄?₂?PO₄?₄O₂:0.01Eu²⁺,and we packed the straight white phosphor to make a self-made LED lamp.The lamp shows good color rendering index?82?and same correlated color temperature?6500K?with the commercial LED lamp.