本實驗利用固相合成法的方式製備不含稀土離子的螢光粉主體CaWO4、BaWO4以及CaNb2O6，並摻雜Dy3+離子作為發光中心，另添加和Dy3+離子相同比例的Na+離子作為電荷補償劑，探討不同晶體結構的主體材料對螢光粉發光性質的影響。實驗結果顯示，Ca0.96Dy0.02Na0.02WO4和Ba0.96Dy0.02Na0.02WO4在900℃的溫度下燒結並持溫20小時後可成功燒結出斜方晶系的白鎢礦結構。而Ca0.96Dy0.02Na0.02Nb2O6則在1100℃溫度下燒結並持溫20小時後燒結出斜方晶系的鎢青銅結構；此化合物有一低溫相變,在650℃的溫度下褪火處理10小時後，可轉變爲正方晶系的鎢青銅結構。
由光致發光光譜顯示,Ca0.96Dy0.02Na0.02WO4, Ba0.96Dy0.02Na0.02WO4以及Ca0.96Dy0.02Na0.02Nb2O6螢光粉體在激發光波長為350nm的激發下，可發出487nm(4F9/2→6H15/2)的藍光和574nm(4F9/2→6H13/2)的黃光，黃光的強度比藍光強，換算出的CIE色度座標Ca0.96Dy0.02Na0.02WO4為(0.34，0.33) 而Ba0.96Dy0.02Na0.02WO4為(0.32，0.29)，均座落在白光區。斜方晶系的Ca0.96Na0.02Dy0.02Nb2O6黃光比藍光強太多，混合的光不在白光區。但是，經退火後的正方晶系Ca0.96Na0.02Dy0.02Nb2O6由於其對稱性的提高，使黃光強度有所下降，換算出的CIE色度座標為(0.32，0.30)，亦座落在白光區。
關鍵字:螢光粉 鎢酸鹽 鈮酸鹽 稀土元素

The aim of this study was to develop some new phosphor whose host material contained no rare-earth (RE) element. We chose CaWO4, BaWO4 and CaNb2O6 as the RE-free host and studied the spectroscopic properties of Dy3+ in these hosts. Na+ was co-doped with Dy3+ in order to maintain the overall charge neutrality. The experiment results showed that after sintering at 900 C for 20 hours Ca0.96Dy0.02Na0.02WO4 and Ba0.96Dy0.02Na0.02WO4 crystallized in the monoclinic Scheelite structure, while the sintering temperature for Ca0.96Dy0.02Na0.02Nb2O6 to form the monoclinic tungsten-bronze (MTB) was 1100 C. The later showed a low temperature phase transition and after annealing at 650 C for 10 hours, the sample transformed to the tungsten-bronze (TTB) structure.
Photoluminescence spectroscopy showed that under the 350 nm excitation Ca0.96Dy0.02Na0.02WO4, Ba0.96Dy0.02Na0.02WO4, and Ca0.96Dy0.02Na0.02Nb2O6 gave out two dominant emissions at 487 nm (4F9/2→6H15/2, blue) and 574 nm (4F9/2→6H13/2, yellow), respectively. The yellow lights were stronger than the blue lights in all three phosphors. The CIE color coordinates for Ca0.96Dy0.02Na0.02WO4 and Ba0.96Dy0.02Na0.02WO4 were calculated to be (0.34, 0.33) and (0.32, 0.29) respectively, which were all located in the white region. The yellow emission of the MTB-structured Ca0.96Dy0.02Na0.02Nb2O6 was far too stronger and the mixture of the two emissions was not in the white region. However, in the TTB-structured Ca0.96Dy0.02Na0.02Nb2O6 the yellow emission was reduced, presumably arising from the higher symmetry of the structure. The CIE color coordinate of the TTB-structured Ca0.96Dy0.02Na0.02Nb2O6 was (0.32, 0.30), which was also in the white region.
Key words:phosphor,Scheelite,rare earth

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