Synthesis And Properties Study Of Rare Earth Doped LaPO₄and Their Composites With Fe₃O₄

As the improving in separation and purification technology of rare earth, research and application of rare earth luminescent materials appealed much interest of many scientists, especially rare earth orthophosphates. This subject has become a research hotspot and has been considered to be a good substitute of organic dyes and quantum dots because of their excellent features of being chemical stable, easy doping, adjustable wavelength and so on. Meanwhile, we have higher requirements on the properties of materials along with the vigorous development of science and technology. We hope to find a kind of material that posseses multifunctional properties. And this gives birth to a new kind of material called composite, which combines two or more kinds of materials having different properties by chemical or physical method to form material with new properties. Magnetic and fluorescent bifunctional material is one of the most rapidly developed composites. And it has already been widely used in biology, biomedicine and other fields.This paper mainly used hydrothermal method to synthesis rare earth ion doped LaPO4with different morphologies. Furthermore, we successfully used rare earth ion doped LaPO4as fluorescent material to prepare a kind of bifunctional material which posseses magnetic and fluorescent properties. The results are as follows:1. A dandelion-like LaPO4was synthesized by a facile hydrothermal process. Tetrabutyl ammonium bromide (TBAB), tartaric acid and ethanol were used to control the morphology of the product and their respective effects on the formation of dandelion-like LaPO4morphology were also studied in detail. The results showed that ethanol played an important role on the assembly of LaPO4nanorods and the formation of dandelion-like LaPO4. The influence of temperature and the doping concentration on the crystal phase of LaPO4were investigated. We abtained pure monoclinic LaPO4at relatively lower temperature of140℃. When doped with Eu3+, they were also monoclinic as long as the molar ratios were below5%. Then, the phase structure transformed from monoclinic to hexaganol LaPO4when the molar ratio further increased.2. A simple hydrothermal process without adding any template was applied to synthesize LaPO4nanorods with length and width of about5μm and250nm, respectively. The result showed that the LaPO4nanorods prepared was monoclinic phase. Gd3+was a good sensitizer to Tb3+. Compared to the sample doped with Tb3+, the luminescent intensity of LaPO4nanorods increased apparently after being co-doped with Tb3+and Gd3+3. A bifunctional material of magnetic and fluorescent was synthesized through a two-step hydrothermal method. The structure, magnetic and fluorescent properties were characterized. The results showed that the as-prepared rare earth doped LaPO4-Fe3O4composite possessed fluorescent and magnetic properties. However, its fluorescent intensity decreased because of the strong absorption to light of Fe3O4.