Sonochemical Synthesis And Their Properties Of Rare Earth Ion Doped GdPO₄ Nanomaterials

Rare Earth ion doped luminescent nanomaterials exhibit many excellent properties becasue rare earth ions have unique electronic structure and transition patterns. They have been extensively used in many fields such as optoelectronic devices, information display and human health care. As a new generation of light-emitting material, Rare Earth ion doped luminescent nanomaterials have become one of the popular research topics. Ultrasonic method has been extensively investigated for its significant advantages such as less-complicated techniques, rapid reaction rate, low temperature, and the ability to form nanoparticles with high purity, fine grain size and finely well distributions.In this thesis, nanoparticles of GdPO4:Eu, GdPO4:Tb were synthesized by ultrasonic method and the samples were characterized by X-ray diffraction(XRD), scanning election microscopy(SEM), Infrared Radiation(IR), Fluorescence Properties(PL) and other testing methods. The interesting topic is the factors on the crystal structure, morphology, and luminescent properties, which include the doping ion concentration, pH, calcination temperature, organic citric acid and glycine. Furthermore, the relationship of the structure and morphology as well as the interrelation among properties was explored. The main contents include:1. Nanoparticles of GdPO4:Eu was synthesized by ultrasonic method at pH=2 and pH=10,respectively. The obtained nanoparticles have nanorod morphology with good crystallinity under pH=2,but spherical morphology with bad crystallinity under pH=10. And the obtained nanoparticles at pH=2 have better fluorescence properties than nanoparticles at pH=10. After calcinations the samples lose crystal water, and the structure changes from hexagonal to monoclinic phase. At the same time, the light emission intensity of sample at 1000 ℃calcined is greater than calcined at 800 ℃.2. Nanoparticles of GdPO4:Tb was synthesized with the same parameters by ultrasonic method under the same condition, namely at pH=2 and pH=10. The results showed similar trend that better crystallinity and fluorescence were given by nanorods obtained at pH=2.After the addition of glycine, the light emission intensity of sample increased for the complex formations which is conducive to the growth of GdPO4 crystals.3.Nanoparticles of GdPO4:(Ce,Tb) was synthesized by ultrasonic method. The morphology changed when citric acid was added. As a result, with the increasing amount of citric acid, the length of the sample particles decreased but the width gradually increased.When the amount of citric acid and gadolinium ion species ratio was 2:1, the strongest light emission was observed in the samples particles which also have better crystallinity and larger particles.