新穎三價鈰和兩價銪離子激活螢光體之製備與結構-發光特性關聯之研究

Abstract

本研究以固態合成法在弱還原氣氛下成功合成出A、B、C、D、E、F、G、H、I等九種不同螢光體主體，所有主體中皆分別摻入Ce3+或Eu2+作為活化劑以取代各主體中Ca2+、Sr2+、Ba2+等格位，經XRD晶相分析以確認主體不因Ce3+或Eu2+之摻入而改變原本晶體結構，再透過漫反射光譜，確認主體在Ce3+與Eu2+的激發波段並無吸收，所有光學特性來自稀土離子。接著，將主體結構加以解析，推測結構與放光特性之間的關係，試圖找出一些規則。稀土離子所取代格位的配位數介於六至十二之間，而Ce3+發光波長介於323 nm至506 nm之間；另一個稀土離子Eu2+的發光波長則介於398 nm至657 nm之間，可見配位環境對活化劑發光波長之影響。此外，本研究將螢光粉進行色度座標量測，發現上述螢光粉主要發射包含紫藍光、藍光、水藍光、綠光、黃光以及橘黃光等色光，某些新穎螢光體具有照明應用的潛力。

In this research we have synthesize nine different types of Eu2+-or Ce3+-doped phosphors with the compositions of Host：Eu2+(or Ce3+) (Host = A、B、C、D、E、F、G、H、I ) under a mildly reducing atmosphere. Each of these compounds was solely doped with Ce3+ or Eu2+,which are expected to substitute for the positions of Ca2+、Sr2+、Ba2+,respectively. By comparing X-ray data of the samples to those reported in database, we are sure that the crystal structures of hosts do not change after doping of 2% rare earth ions. Through the measurements of diffuse reflectance spectrum for both doped and un-doped samples, we found that all of the optical emissions were resulted from the doped rare earth ions. We have also analyzed the structure of the hosts and made attempts to correlate the luminescence behaviors and crystal structure. In this phosphors synthesized in this work, rare-earth ions were found to substitute and enter the cation sites with six to twelve coordination number. The emission wavelength were found to vary from 323 nm to 506 nm as in the case of Ce3+-doped phosphors and 398 nm to 657 nm as in Eu2+-doped phosphors. Additionally, the C.I.E. chromaticity coordinates show that these phosphors emit hues including violet, blue, aqua blue, green, yellow and orange.