Growth and characterization of semi-insulating GaN films grown by MOCVD

High resistivity unintentionally doped GaN films were grown on (0001) sapphire substrates by metalorganic chemical vapor deposition. The surface morphology of the layer was measured by both atomic force microscopy and scanning electron microscopy. The results show that the films have mirror-like surface morphology with root mean square of 0.3 nm. The full width at half maximum of double crystal X-ray diffraction rocking curve for (0002) GaN is about 5.22 arc-min, indicative of high crystal quality. The resistivity of the GaN epilayers at room temperature and at 250 degrees C was measured to be approximate 10(9) and 10(6) Omega(.)cm respectively, by variable temperature Hall measurement. Deep level traps in the GaN epilayers were investigated by thermally stimulated current and resistivity measurements.

Growth of high quality semi-insulating InP single crystal by suppression of compensation defects

Deep level defects in as-grown and annealed SI-InP samples were investigated by thermally stimulated current spectroscopy. Correlations between electrical property, compensation ratio, thermal stability and deep defect concentration in SI-InP were revealed. An optimized crystal growth condition for high quality SI-InP was demonstrated based on the experimental results.

In-situ synthesis of AlN powders and composite AlN powders with yttrium addition

Using Al-Mg and Al-Mg-Y alloys as raw materials and nitrogen as gas reactants, AIN powders and composite AIN powders by in-situ synthesis method were prepared. AIN lumps prepared by the nitriding of Al-Mg and Al-Mg-Y alloys have porous microstructure, which is favorable for pulverization. They have high purity, containing 1.23 % (mass fraction) oxygen impurity, and consisted of AIN single phase . The average particle size of AIN powders is 6.78 mum. Composite AlN powders consist of AlN phases and rare, earth oxide Y2O3 phase. The distribution of particle size of AIN powders shows two peaks. In view, of packing factor, AIN powders with such size distribution can easily be sintered to high density.

Growth of ZnO single crystal by chemical vapor transport method

ZnO crystals were grown by CVT method in closed quartz tube under seeded condition. Carbon was used as a transport agent to enhance the chemical transport of ZnO in the growth process. ZnO single crystals were grown by using GaN/sapphire and GaN/Si wafer as seeds. The property and crystal quality of the ZnO single crystals was studied by photoluminescence spectroscopy and X-ray diffraction technique.

Study on surface morphology of GaN growth by MOCVD on GaN/Si(111) template

The surface morphology of GaN grown by MOCVD on GaN/Si template was studied. Rough morphology and deep pinhole defects on some surface areas of the samples were observed and studied. The formation of rough morphology is possibly related to Ga-Si alloy produced due to poor thermal stability of template at high temperature. The deep pinhole defects generated are deep down to the surface of MBE-grown GaN/Si template. The stress originated from the large thermal expansion coefficient difference between GaN and Si may be related to the formation of the pinhole defects. The surface morphology of the GaN can be improved by optimizing the GaN/Si template and decreasing the growth temperature.

Growth and characterization of semi-insulating GaN films grown by MOCVD

High resistivity unintentionally doped GaN films were grown on (0001) sapphire substrates by metalorganic chemical vapor deposition. The surface morphology of the layer was measured by both atomic force microscopy and scanning electron microscopy. The results show that the films have mirror-like surface morphology with root mean square of 0.3 nm. The full width at half maximum of double crystal X-ray diffraction rocking curve for (0002) GaN is about 5.22 arc-min, indicative of high crystal quality. The resistivity of the GaN epilayers at room temperature and at 250 degrees C was measured to be approximate 10(9) and 10(6) Omega(.)cm respectively, by variable temperature Hall measurement. Deep level traps in the GaN epilayers were investigated by thermally stimulated current and resistivity measurements.

Growth of high quality semi-insulating InP single crystal by suppression of compensation defects

Deep level defects in as-grown and annealed SI-InP samples were investigated by thermally stimulated current spectroscopy. Correlations between electrical property, compensation ratio, thermal stability and deep defect concentration in SI-InP were revealed. An optimized crystal growth condition for high quality SI-InP was demonstrated based on the experimental results.

基于NMR的代谢组学方法对稀土生物效应的研究

近年来，随着高场傅里叶变换核磁共振波谱仪灵敏度的提高、分辨率的增加、化学位移的扩展、多脉冲实验技术的发展以及计算机技术的不断进步，使NMR技术在生物和医学领域的应用有了飞速的发展。而基于NMR技术结合模式识别的代谢组学方法更是在医学临床诊断、药物毒性、环境毒理学等领域得到广泛应用。 稀土由于其特殊的电子层结构在工业、农业、畜牧业和现代生物医学上具有非常广泛的应用。本论文工作采用基于核磁共振技术的代谢组学方法，分别对给药稀土钕、镨(农用稀土微肥常乐中两种主要成分)以及重稀土钆后大鼠的体液(尿液、血清)和组织(肝、肾)中代谢物的浓度变化进行了分析。结合生化指标数据和组织切片显微照片，系统的研究了稀土钕、镨和钆的急性生物效应。 运用高分辨1H NMR技术，检测分析了大鼠腹腔注射不同剂量硝酸钕(2，10，50 mg/kg体重，48 h)、氯化钆(10，50 mg/kg体重，168 h)和硝酸镨(2，10，50 mg/kg体重，168 h)后尿液、血清及肝肾组织中的代谢物如柠檬酸、肌酸、肌酸酐、二甲胺、二甲基甘氨酸、氮氧三甲胺(TMAO)、氨基酸、乳酸、琥珀酸、牛磺酸、胆碱、甘油三脂、糖元等的浓度、物种的变化。结合模式识别方法，并根据血中生化指标和组织光镜图，对稀土在体内与细胞、组织和器官的作用机理及急性毒性进行了有意义的探讨。结果表明：高剂量硝酸钕的引入可能使动物体内的代谢出现异常，动物肾脏和肝脏的特定部位(如肾小管、肾乳头、肝脏线粒体)受到选择性的损伤；氯化钆对大鼠造成损伤的靶器官是肝脏，同时肾脏功能也受到伤害，其主要表现为通过改变大鼠体内酶代谢而使大鼠肝脏中正常的能量代谢(糖代谢和脂肪代谢)和氨基酸代谢等受到扰乱，同时能使肾脏中维持渗透平衡的渗透质浓度降低；硝酸镨靶向器官为肝脏和肾脏，以肝脏为主，且呈现明显的剂量-反应关系，低、中剂量Pr(NO3)3对大鼠肝脏和肾脏的损伤在168 h内是可逆的。基于NMR的代谢组学方法也可用于其它化合物的毒性研究。

有机磷（膦）酸双溶剂体系及离子液基体系对稀土萃取的研究

本文系统研究了由酸性磷（膦）类萃取剂所构成的双溶剂萃取体系对稀土的协同萃取效应；考察了添加剂对磷（膦）类萃取体系的分离能力，反萃性能，界面性质及动力学机理的影响；运用绿色溶剂---室温离子液体替代挥发性有机溶剂为稀释剂，研究了磷（膦）类萃取剂在离子液体中萃取稀土的性能，具体的研究内容如下： 1． 考察了HDEHP， HHEOIPP， Cyanex272， Cyanex302，Cyanex301分别与HEHEHP构成混合萃取体系在盐酸介质中对RE3+的萃取和分离性能，推导了协萃反应方程式，计算了相邻稀土元素间的分离系数，讨论了各混合体系对部分稀土相互分离的可能性，并从萃取剂结构方面对不同萃取体系萃取能力的差别给出了解释。 2． 用层流恒界面池法研究了添加剂isooctanol对HEHEHP萃取体系萃取Yb3+的传质动力学的影响，综合搅拌速率判别法，界面判别法，温度判别法，得出了萃取过程为伴随有界面化学反应的扩散传质。考察了水相酸度、有机相浓度等因素对反应速率的影响，提出了萃取速率方程及动力学传质机理，计算了扩散层厚度及扩散速率常数，建立了传质模型。 3． 考察了甲庚醇浓度、温度、离子强度等因素对HEHEHP-isooctanol体系界面活性的影响，并定性探讨了极性添加剂isooctanol对HEHEHP-Yb3+-HCl体系萃取动力学的影响。 4． 选择室温离子液体[C8mim][PF6] 作为溶剂，系统研究了磷(膦)类萃取剂HEHEHP对稀土的萃取能力，计算了HEHEHP- IL体系的分离系数，推测了萃取体系的反应机理，并与相同萃取条件下庚烷体系中HEHEHP对稀土的萃取性能进行了比较。

稀土元素与过渡金属元素的溶剂萃取与树脂吸附研究

该论文围绕金属元素的溶剂萃取和树脂吸附进行了一系列研究.考察了几种萃取剂的混合体系对稀土元素及过渡金属元素的萃取效应,同时,研究了酸性有机磷(瞬)类萃淋树脂对二价过渡金属元素的吸附性能,并讨论了它们用于分离金属元素的可能性.1.研究了盐酸和硝酸介质中β-二酮类萃取剂HPMBP与硫代中性有机磷(膦)类萃取剂Cyanex471X单独及混合体系对稀土元素La(Ⅲ)的萃取机理.2.研究了Cyanex272与伯胺N1923的混合物对Zn(Ⅱ)的协同萃取效应,得出了协萃反应方程式和平衡常数.3.考察了伯胺N1923与中性有机磷(膦)类萃取剂DEH/EHP的混合体系在盐酸介质中对Zn(Ⅱ)和Cd(Ⅱ)的萃取效应,研究了萃取机理,并研究了此混合体系对Zn(Ⅱ)和Cd(Ⅱ)的分离.4.揭示了Cyanex923萃取硝酸过程中出现第三相的机理和三相的相行为,讨论了第三相形成的影响因素.5.考察了盐酸介质中HEOPPA萃淋树脂对二价过渡金属元素的吸附平衡,得出了吸附反应方程式.

基于NMR的稀土生物效应代谢组学研究

近年来，随着高场傅里叶变换核磁共振波谱仪灵敏度的提高、分辨率的增加、化学位移的扩展、多脉冲实验技术的发展以及计算机技术的不断进步，使NMR技术在生物和医学领域的应用有了飞速的发展。而基于NMR技术结合模式识别方法的代谢组学方法更是在医学临床诊断、化合物生物效应、环境毒物学等领域得到广泛应用。稀土由于其特殊的电子层结构在光学、磁学领域应用非常广泛，同时因为其对农作物生长具有明显的促进作用，因此也被大量使用于农业中。本论文工作围绕农用稀土微肥常乐中两种主要成分斓、饰以及重稀土噜的急性生物效应，采用基于核磁共振技术的代谢组学方法，结合生化指标和组织切片显微照片，对给药稀土大鼠的体液（尿液、血清）和组织（肝、肾）进行了系统的研究。运用高分辨IHNMR技术，检测分析了大鼠腹腔注射不同剂量硝酸悯（2．0，10，50mg／kg体重）、硝酸饰（2．0，10，50mg瓜g体重）和灌胃给药硝酸噜（0．01，0．05，0．2，2，10，100mg／kg体重）48小时内尿液及48小时后血清及肝肾组织中的代谢物如柠檬酸、酮体、肌酸配、二甲胺、二甲基甘氨酸、TMAO、氨基酸、乳酸、唬拍酸、牛磺酸、甘油三脂、糖元等的浓度、物种的变化。结合模式识别方法，并根据血中生化指标和组织光镜图，对稀土在体内与细胞、组织和器官的作用机理及急性毒性进行了有意义的探讨。结果表明，各剂量硝酸悯主要导致大鼠肝脏受损，且损害程度与剂量成正比关系；而高剂量硝酸饰（10，50mg／kg体重）不仅在48小时内造成大鼠肝脏的能量代谢（糖代谢、脂肪代谢）紊乱，并导致肾小管炎症和肾乳头坏疽；重稀土噜在低剂量（0．2，2．0mg／kg体重）时主要导致肾小管重吸收能力下降，而高剂量（10，100mg众g体重）时主要表型为肝毒。该方法可用于其它药物的毒理研究。

多元氨基酸、肽体系中稀土存在形态及配位作用特点研究

本文研究了稀土在多元氨基酸小分子生物配体体系存在形态及其作用特点，探索了稀土元素在生物体内的分布、代谢及其生物效应的机理，同时研究了稀土与复杂的生物大分子作用及稀土氨基酸固体配合物。