Preparation of high-performance luminescent oxide materials and investigation of the local structure surrounding luminescent centers by means of magnetic resonance spectroscopy

1.本文用磁共振波谱研究了氧化物发光材料的制备，如Eu（II）掺杂的碱铝酸盐、Eu（II）和Dy（III）掺杂的硼磷酸锶和氧化锌，并沿着研究了发光中心周围的局域结构。对于长磷光Eu（II）掺杂的碱性铝酸盐，它被澄清，Eu（II）和Dy（III）离子占据两个不同的低对称性Sr网站由高频EPR光谱。此外，使用紫外线照射的光EPR检查表明，有缺陷附近的Dy（III）的网站。据此提出了长磷光的机理。对于SrBPO_5：Eu的X射线存储荧光粉，发现有两个Eu（II）位。首次成功地分析了多晶材料中低对称Eu（II）格位的EPR谱.为了研究^8S基态离子的高频EPR谱，开发了傅里叶变换蒙特卡罗和全蒙特卡罗EPR谱模拟程序。研究发现，尽管FT Monte Carlo方法与商用软件一样快，但计算得到的谱线形状却远优于后者.对于ZnO，这是一个有前途的材料与紫外线发射，外延生长进行了研究，使用卤化锌作为起始原料。发展了卤化物气相外延和常压原子层外延生长技术.当在蓝宝石（001）衬底上生长外延ZnO薄膜时，发现用作起始材料的卤化物之间的光致发光性质存在差异。用ZnI_2制备的ZnO薄膜在室温下有380 nm左右的发光，而用ZnCl_2制备的ZnO薄膜没有发光。电子顺磁共振谱研究表明，前者的薄膜中几乎没有缺陷。

1. Preparation of oxide luminescent materials such as EU(II)-doped alkaline aluminates, Eu(II)- and Dy(III)-doped strontium borophosphate and zinc oxides are examined along with the local structure surrounding luminescent centers by means of magnetic resonance spectroscopy. For the long phosphorescent Eu(II)-doped alkaline aluminates it was clarified that the Eu(II) and Dy(III) ions occupy two different low symmetry Sr sites by high frequency EPR spectroscopy. Also, photo-EPR examination using UV-irradiation suggested that there are defects near Dy(III) sites. Consequently, the mechanism of the long phosphorescence was proposed. As for the X-ray storage phosphor of SrBPO_5 : Eu it was found that there are two Eu(II) sites. It is for the first time that the EPR spectra of the low symmetry Eu(II) sites in polycrystalline materials are successfully analyzed.2. In order to examine the high frequency EPR spectra of ^8S ground state ions Fourier transformed Monte Carlo and Full Monte Carlo EPR spectral simulation programmes were developed. It is found that although the FT Monte Carlo method is as fast as the commercially available software, the calculated spectral line shape is far better than the latter one.3. For ZnO, which is one of the promising materials with UV emission, the expitaxial growth were examined using zinc halides as starting materials. Growth techniques of halide vapor expitaxy and atomic layer epitaxy under atmospheric pressure are developed.4. When the epitaxila ZnO films were grown on a sapphire (001) substrate, it was found that there is a difference in photoluminescence properties between halides used as starting materials. The ZnO films prepared using ZnI_2 showed an emission at about 380 nm at room temperature, while the films prepared using ZnCl_2 showed no emission. EPR spectroscopic investigation proved that the former films contain little defects in them.