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

1.利用核磁共振技术研究了掺Eu(II)的碱性铝酸盐、掺Eu(II)和Dy(III)的硼磷酸锶和氧化锌等氧化物发光材料的制备及其发光中心周围的局域结构。对于长磷光掺Eu(II)的碱性铝酸盐，高频EPR谱表明Eu(II)和Dy(III)离子占据了两个不同的低对称性锶中心。此外，紫外光照射的光电子顺磁共振检测表明，Dy(III)位附近存在缺陷。在此基础上，提出了长磷光发光的机理。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性Eu(II)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。结果表明，虽然傅里叶变换蒙特卡罗方法的计算速度与商用软件相当，但计算得到的谱线形状远好于商业软件。以卤化锌为原料，研究了具有紫外光发射前景的氧化锌的外延生长。开发了常压下卤化物气相外延和原子层外延生长技术。当外延氧化锌薄膜生长在蓝宝石(001)衬底上时，发现以卤化物为起始原料的光致发光性质有所不同。用氯化锌制备的氧化锌薄膜在室温下有约380 nm的发射，而用氯化锌制备的薄膜在室温下没有发射。EPR谱研究表明，前一层膜中几乎没有缺陷。

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.