Sonochemical Synthesis And Their Properties Of Rare Earth Ion Doped YPO₄ Luminescent Materials

As a new generation of optical material, rare earth phosphate luminescent materials have become the most potential for development and new market applications. Because they exhibit many excellent properties such as the strong absorption capacity, the high conversion efficiency, the strong launch capabilities in UV- visible- infrared region, the good physical and chemical stability. They have been widely used in optoelectronic devices, the information display, human health care and other fields. Ultrasonic method has been extensively investigated for its significant advantages in the study of chemistry such as mild conditions, simple devices, easy controlling process, no secondary pollution and many other unique merits.In this thesis, taken yttrium phosphate as substrate, terbium ion and europium ion-doped rare earth phosphate luminescent material were synthesized by ultrasonic method and characterized by X-ray diffraction?XRD?, Infrared Radiation?IR?,scanning election microscopy?SEM?, Fluorescence Properties?PL? and other testing methods. The attention of the study focuses on the factors in the crystal structure,morphology, crystal size and luminescent properties, which include the pH, the doping Ce percentage composition, the PO43-/RE3+ molar ratio, different phosphate source, the additive content, the calcination temperature and other conditions. The main contents are:1. Luminescent materials YPO₄:?Ce,Tb? were synthesized by the ultrasonic method. The results show that only under the condition of pH =1, the sample will have a better crystal structure, a sheet morphology and showing characteristic emission of Tb3+ : 5D4-7FJ?J =3,4,5,6?; PO43-/RE3+ molar ratio affects the morphology of the sample, but does not change the crystal structure of the sample. When PO43-/RE3+ molar ratio was 5:1, the morphology was the most helpful to improve theluminescence properties of the sample; a small amount of Ce3+ as a sensitizer plays a role in transferring energy to Tb3+, and promotes the light emission intensity of the sample. When the value of the Ce percentage composition is 5%, the YPO₄:? Ce,Tb?luminescent material shows the best luminous performance.2. As the crystal structure and morphology of the samples vary with the phosphate source in the preparation process, the luminescent properties of samples exhibit different intensities. The morphology changed into flower-like structure and luminescent intensity has also been greatly improved when oxalic acid was added with the molar ratio of oxalic acid and rare earth ions as 0.25:1.3. Luminescent materials YPO₄:Eu were synthesized by the ultrasonic method.When citric acid was added with the amount of citric acid and rare earth ions molar ratio was 1:1, the YPO₄:Eu luminescent material shows the best luminous performance. After calcinations, the luminous performance of the samples greatly improved, because the samples lose crystal water so that reducing the fluorescence quenching of-OH. Additionally, the crystallinity of the samples becomes better and the morphology varies from sheet structure into more uniform and finernano-spherical structure with the increase of calcination temperature, which are all conducive to improve the luminous intensity of YPO₄:Eu.