| 摘要註: |
本研究以矽酸鹽類中Sr2SiO4作為主體晶格材料,ZnO以x=0, 0.2, 0.4比例取代Sr作為增感劑形成Sr2-xZnxSiO4組成,而稀土金屬元素Eu2O3則以0.5mol%, 0.75mol%, 1mol%比例作為活化劑摻雜至主體晶格Sr中使之被取代,共有Sr2SiO4 : 0.5mol% Eu2O3, Sr2SiO4 : 0.75mol% Eu2O3, Sr2SiO4 : 1mol% Eu2O3, Sr1.8Zn0.2SiO4 : 0.5mol% Eu2O3, Sr1.8Zn0.2SiO4 : 0.75mol% Eu2O3, Sr1.8Zn0.2SiO4 : 1mol% Eu2O3, Sr1.6Zn0.4SiO4 : 0.5mol% Eu2O3, Sr1.6Zn0.4SiO4 : 0.75mol% Eu2O3,Sr1.6Zn0.4SiO4 : 1mol% Eu2O3九種成份,並使用SrCO3、SiO2、ZnO、Eu2O3經由1000°C、1100°C、1200°C、1300°C各燒結溫度處理的固態反應法取得螢光粉體,以SEM、PL、XRD、CIE分析來討論其螢光性質是否改善並得知螢光強度相對優異的成份比例。由PL特性可知成份為Sr1.8Zn0.2SiO4 : 0.75 mol% Eu2O3時有最強的螢光放光強度,但添加到1mol% Eu2O3 時強度反而下降,其原因為活化劑濃度超過一定值時,發光效率不再提升,使受外界激發的能量於主體晶格中消耗,活化劑間傳遞機率超過發射機率,導致激發能量重複於晶格間傳遞而消耗,此為濃度淬滅現象,發射出來的能量較低,故其強度在濃度較高時反而下降。另外,Sr1.6Zn0.4SiO4的螢光放光強度劣於Sr1.8Zn0.2SiO4,原因為Zn的取代量過多,使得晶體結構扭曲,導致能量傳遞過程中遭到損耗後放光強度下降。製備螢光粉體即是預期被使用在LED照明元件上,由CIE色度座標顯示,此次研究的粉體為接近紅色,為達所需的LED光源,可藉此結果再搭配其他光源或其他粉體以利後續應用。 In this work, Sr2SiO4 was used as host material and ZnO with ratio of 0, 0.2, 0.4 was used to substitute Sr and formed the Sr2-xZnxSiO4 compositions. Rare earth Eu2O3 with the ratio of 0.5 mol%, 0.75mol%, and 1mol %, respectively, was used as activator and doped into the Sr2-xZnxSiO4 compositions. Total has nine compositions for Sr2SiO4 : 0.5mol% Eu2O3, Sr2SiO4 : 0.75mol% Eu2O3, Sr2SiO4 : 1mol% Eu2O3, Sr1.8Zn0.2SiO4 : 0.5mol% Eu2O3, Sr1.8Zn0.2SiO4 : 0.75mol% Eu2O3, Sr1.8Zn0.2SiO4 : 1mol% Eu2O3, Sr1.6Zn0.4SiO4 : 0.5mol% Eu2O3, Sr1.6Zn0.4SiO4 : 0.75mol% Eu2O3,Sr1.6Zn0.4SiO4 : 1mol% Eu2O3 were obtained by mixing SrCO3, SiO2, ZnO, and Eu2O3 and the phosphors were obtained by using solid state reaction method at 1000°C、1100°C、1200°C、1300°C sintering temperature, respectively. When SEM, PL, XRD, CIE analysis were used to check the enhancement of the phosphor property and find composition with the better phosphor intensity. From PL analysis' results, Sr1.8Zn0.2SiO4:0.75mol% Eu2O3 had the maximum phosphor intensity, but the fluorescence intensity decreased as the Eu2O3 was increased to 1mol%. If the concentration of activator is more than a criterion, the emission efficiency will no longer ramp up and make energy which is excited by surrounding being consumed in host, because energy transfers between activator is easier to happen rather than radiate, leading to energy consumption happening in energy transfers during the crystal structure and concentration quenching effect will happen. The emitted energy is so lower that the emission efficiency decays when the activator has higher concentration. On the other hand, the fluorescence intensity of Sr1.6Zn0.4SiO4 phosphor is weaker than that of Sr1.8Zn0.2SiO4 phosphor. When more Zn is used to substitute Sr, the crystal structure of Sr2-xZnxSiO4 compositions will be distortion and that will lead to exciting energy consumption. The prepared Sr2-xZnxSiO4 phosphors are hoped to be used in the LED devices. From CIE analysis' results, the Sr2-xZnxSiO4 phosphors are revealed a near red light, in order to get required LED color, using the phosphors or powder with other colors to facilitate the application. |