LaVO_4∶Eu^(3+)水热制备及荧光性能研究

Study on Hydrothermal Preparation and Fluorescence Properties of LaVO_4∶Eu^(3+)

以NH4VO3、LaCl3·nH2O为原料,以EDTA为结构导向剂,采用水热法合成了LaVO4∶Eu3+粉体。通过X射线粉末衍射、扫描电子显微镜、荧光光谱仪对水热产物进行了表征。水热体系pH值对EDTA的结构导向作用有一定的影响。水热体系pH值为4~11时,EDTA具有明显的结构导向作用,合成了单一相的t-LaVO4,水热产物的微观形貌为长径比不同的纳米棒及由纳米棒组成的束状棒,碱性水热体系比酸性水热体系制备的产物结晶度高。水热产物对200~350nm的紫外光具有良好的吸收,在273nm紫外光激发下,所有样品均具有以红光为主的发射峰,碱性水热体系比酸性水热体系制备的产物荧光强度高,其中水热体系pH值为11时制备的水热产物荧光强度远高于其他pH值下制备的产物。当水热体系pH值为12、13时,EDTA失去了络合能力,产物为以m-LaVO4为主的纳米颗粒,水热产物的荧光强度降低。

Using NH4VOa and LaCla·nH2O as the raw materials, LaVO4 ： Eu3＋ powders were successfully obtained by a structure directing agent of EDTA via hydrothermal method. The obtained powders were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and fluorescence spectrometer （PL）. The pH values of hydrothermal solution produced effects, to a certain extent, on structure directing function of EDTA. When the pH values of hydrothermal solution were between 4 and 11, the structure directing function of EDTA was obvious. The single phase of t-LaVO4 was synthesized with the morphology of nanorods or bundles assembled by nanorods. The crystallinity of products synthesized at the alkaline hydrothermal solution was better than that synthe- sized at the acid hydrothermal solution. The UV-Vis light of 200--350 nm was well absorbed by hydrothermal pro- ducts. Under the excitation UV light number of 273 nm, the emission peaks of all products exhibited primarily in red. The products synthesized at the alkaline hydrotherrnal solution had the higher fluorescence intensities than that synthe- sized at the acid hydrothermal solution. Especially, the fluorescence intensity of the products synthesized at pH value of 11 was far higher than that of the products synthesized at other pH values. When the pH values of hydrothermal solution were 12 and 13, the structure directing function of EDTA was lost. The phase of the products was monoelinic type （m-） LaVO4 with lower fluorescence intensity.