采用水热法制备了Yb3+,Ho3+,Nd3+离子共掺杂的钨酸钆钠纳米晶(NaGd(WO4)2∶Yb3+,Ho3+,Nd3+),并在800℃进行了热处理.分另采用X射线衍射(XRD)、场发射扫描电镜(SEM)和荧光光谱仪(PL)对纳米晶的晶体结构、微观形貌和上转换发光性质进行了表征.XRD结果显示样品属于四方晶系、白钨矿结构.SEM图谱表明所得纳米晶具有较好的分散性,颗粒大小约为50 nm.在980 nm激光激发下,NaGd(WO4)2∶Yb3+,Ho3+,Nd3+纳米晶发出546 nm的绿光与660 nm红光,分别对应Ho3+离子的5 F4,5S2→5I8和5F5→5I8能级跃迁.当Nd3+离子掺杂浓度为0.5％(摩尔分数)时,纳米晶的发光强度最大.随着Nd3+离子掺杂量的增加,红光与绿光的相对强度比逐渐减小,纳米晶的光谱由橙色光向黄色光区域变化.本文对NaGd(WO4)2∶Yb3+,Ho3+,Nd3+纳米晶的光谱调控和上转换发光机制进行了研究.
NaGd (WO4) 2 nanocrystals co-coped with Yb3 +,Ho3 + and Nd3 + ions (NaGd (WO4) 2 ∶ Yb3 +,Ho3 +,Nd3+) were synthesized through hydrothermal method followed by a subsequent heat treatment process at 800 ℃.The structure,morphology and up-conversion luminescence of the samples were investigated by X-ray diffraction (XRD),field emission scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL).The XRD results indicated that the samples crystallize in tetragonal structure and belong to the tungstate family.The SEM results showed that the sample has nice dispersibility with grain diameter of about 50 nm.Under the excitation of 980 nm laser,the samples show green (546 nm) and red emission (660 nm),which are corresponding to the energy transition of 5 F4,5 S2→5 I8 and 5 F5→5I8 of Ho3 +,respectively.The luminescence intensity reaches maximum with Nd3 + doping concentration up to 0.5 ％.With the increase of the concentration of Nd3 +,the relative intensity ratios of red to green light decrease gradually and the spectra of the samples change from orange to yellow.The mechanism of spectrum regulation and up-conversion luminescence of NaGd(WO4)2 ∶Yb3+,Ho3 +,Nd3+ nanocrystals were discussed.
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