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以氟化钾(KF)作为助熔剂,选用70~90℃/cm的固液界面温度梯度,通过改进的助熔剂-布里奇曼方法生长出了Dy3+离子掺杂的α-NaYF4单晶体.测试了样品的X射线粉末衍射,吸收光谱,激发光谱,以及在不同紫外光激发下的发射光谱,分析了样品的的物相和光谱特性.应用色度学理论计算了Dy3+离子掺杂α-NaYF4单晶的色度坐标和色温.结果表明:当原料组份配比为30NaF-18KF-52YF3时,有利于大尺寸晶体生长.原料中KF的加入起到助熔剂作用,它改变了NaF-YF3二元系相图并且降低了α-NaYF4的熔点,使得α-NaYF4能从熔融的NaF-KF-YF3混合物中结晶出来,最后生长出透明的α-NaYF4单晶体.实验发现大多KF被排析在生长后期的晶体顶端,KF的加入没有对α-NaYF4单晶体的结构产生影响.在348nm紫外光激发下,单晶体可发射出蓝光约479nm,黄光约571nm以及弱的红光约659nm.其中1.299mol%Dy3+掺杂浓度的α-NaYF4单晶体发射的蓝、黄与红光可耦合出色坐标x=0.285,y=0.338以及色温为8 065K的白光.这些新型材料在紫外激发的白光二极管领域具有潜在的应用.
Dy3 + doped α-NaYF4 single crystals were grown by a modified flux-Bridgeman method using potassium fluoride (KF) as a flux and a solid-liquid interface temperature gradient of 70 ~ 90 ℃ / cm. The X-ray powder diffraction, absorption spectra, excitation spectra and emission spectra of samples were analyzed by X-ray powder diffraction, and the phase and spectral characteristics of the samples were analyzed.Using the theory of chrominance, the doping of Dy3 + ion with α-NaYF4 The results show that when the ratio of raw materials is 30NaF-18KF-52YF3, it is beneficial to the growth of large-size crystals. The addition of KF in raw materials acts as a flux, which changes the content of NaF-YF3 Binary phase diagram and reduce the melting point of α-NaYF4, α-NaYF4 can be crystallized from the molten mixture of NaF-KF-YF3, the final growth of transparent α-NaYF4 single crystal was found that most of the KF was drained In the late growth stage, the addition of KF did not affect the structure of α-NaYF4 single crystals.The single crystal could emit about 479nm blue light, about 571nm yellow light and about 659nm red light under the excitation of 348nm UV light, of which 1.299mol % Dy3 + doping concentration of α-NaYF4 single crystal blue emission Yellow and red light may be coupled outstanding coordinates x = 0.285, y = 0.338 and the color temperature of these new materials have potential applications in the white light of the white LED 8 065K ultraviolet excitation of the field.