Ln-Si-Al-O-N五元体系新型氧氮化物材料的制备、结构和性能研究

发布时间：2018-04-01 07:25

本文选题：JEM相Sialon　切入点：AlN多型体　出处：《中国地质大学(北京)》2015年博士论文

【摘要】：本文系统研究了Ln Si Al O N五元体系中的几种新型氧氮化物材料的制备、结构和性能。包括:(1)JEM相Nd-Sialon正交阵列微晶的生长机理、不同形貌形的形成机制和单晶发光性能;(2)不同稀土(Ln=Ce、Pr、Nd和Sm)掺杂JEM相Ln Si6-zAl1+zOzN10-z的单晶结构解析、掺杂稀土种类对z值和晶体结构的影响;(3)Nd和Sm掺杂JEM相粉体的制备;(4)低温无压烧结致密Al N多型体复相陶瓷的制备、显微结构、力学性能和断裂机制;(5)新型“114”氮化物的制备和晶体结构研究。Nd-Sialon微晶阵列的生长机理为VLS和VS的协同机制,楔形晶和针形晶的形成取决于富Fe小球在晶体尖端的相对位置;在紫外光激发下Nd-Sialon单晶体可以发出峰值为405nm的蓝光。单晶结构研究表明,JEM相Ln-Sialon均为正交晶系,空间群为Pbcn,稀土元素Ln可以为La~Sm。各稀土掺杂的JEM相的z值不同且在很小的范围,从~1.0(La-JEM)降低到~0.2(Sm-JEM)。JEM相的晶胞参数随着稀土离子半径的减小而减小,而计算密度则为增加的趋势。另外,在相应的z值内,制备得到的Sm-JEM和Nd-JEM粉体纯度最高,分别为90.7wt%和97.1wt%。另外,通过对稀土氧化物的优化,成功地在1650°C温度下无压烧结制备获得致密Al N多型体复相材料,烧结机理为瞬时液相烧结,优化体系为Gd Si Al O N。该烧结温度比以往报导的热压烧结温度还低至少100°C,且所制备的材料的室温力学性能与热压烧结的Al N多型体材料相当。该复相材料由部分具有孪晶结构的板片状15R、六方状β-Sialon和晶界U相Sialon等组成。该材料的断裂模式为沿晶和穿晶断裂并存。首次合成得到“114”型氮化物Ln Al(Si4-xAlx)N7-y□yOδ单晶,并成功合成得到高纯度的La-114粉体。该氮化物为首例在非高压条件下合成、具有[Al N6]配位的无机化合物。单晶结构解析和中子衍射分析表明,其晶体结构属于六方晶系,空间群为P63mc,结构中的反立方八面体间隙为Ln,八面体间隙为Al,且四面体间隙为Si/Al,且少量氧(δ)可进入其结构中的八面体空穴。获得了27Al NMR数据作为直接证据,证明结构中[Al N6]配位的存在,其化学位移为1.6 ppm;并且表征了该新型化合物的XPS谱、高分辨透射电镜形貌和拉曼光谱等特征。归纳和对比了已报导的“114”型化合物和晶体结构差异。
[Abstract]:In this paper, the preparation, structure and properties of several new oxygen nitride materials in Ln / Si / Al / O / N quaternary system have been systematically studied, including the growth mechanism of Nd-Sialon orthogonal array microcrystals. The formation mechanism of different morphologies and luminescence properties of single crystals are discussed. The crystal structure of Ln Si6-zAl1 zOzN10-z doped with different rare earth elements LnnCe PrN ND and Sm2) doped with Ln Si6-zAl1 zOzN10-z is analyzed. Effect of doped rare Earth species on z value and Crystal structure the preparation and Microstructure of Si _ 3ND and Sm doped JEM Powders prepared by low temperature pressureless Sintering densified Al _ N Polyphase Ceramics. Preparation and Crystal structure of New Type "114" Nitride; the growth mechanism of Nd-Sialon microcrystal array is the synergistic mechanism of VLS and vs, and the formation of wedge-shaped and needle-shaped crystals depends on the relative position of Fe-rich microspheres at the tip of the crystal. Under UV excitation, Nd-Sialon single crystal can emit blue light with a peak value of 405nm. The single crystal structure study shows that the Ln-Sialon phase is orthogonal, the space group is Pbcn, and the rare earth element Ln can be La Si Sm. The z values of the rare earth doped JEM phase are different and in a very small range. The unit cell parameters of the phase decreased with the decrease of the radius of rare earth ions, but the calculated density was increased. In addition, the purity of Sm-JEM and Nd-JEM powders were 90.7 wt% and 97.1wtrespectively in the corresponding z values, which were 90.7 wt% and 97.1wt. respectively, the purity of the prepared powders was 90.7 wt% and 97.1wtrespectively, and the purity of the prepared powders was 90.7 wt% and 97.1wt. respectively, and the purity of the prepared powders was 90.7 wt% and 97.1wtrespectively. By optimizing the rare earth oxides, the dense Al N polymorphic multiphase materials were successfully prepared by pressureless sintering at 1650 掳C, and the sintering mechanism was instantaneous liquid phase sintering. The optimized system is Gd / Si / Al / N. The sintering temperature is at least 100 掳C lower than the previously reported hot pressing sintering temperature, and the mechanical properties at room temperature of the prepared materials are comparable to those of Al N polymorphic materials sintered by hot pressing. Lamellar 15R with twin structure, hexagonal 尾 -Sialon and grain boundary U phase Sialon are formed. The fracture mode of this material is intergranular and transgranular fracture. "114" type nitride Ln Al(Si4-xAlx)N7-y-yO 未 single crystal is synthesized for the first time. High purity La-114 powder was synthesized successfully. The nitride is the first inorganic compound with [AlN6] coordination in non-high pressure condition. The single crystal structure analysis and neutron diffraction analysis show that its crystal structure belongs to hexagonal crystal system. The space group is P63mc, the anticubic octahedron gap is Ln, the octahedron gap is Al, and the tetrahedron gap is Si / Al, and a small amount of oxygen (未) can enter the octahedron hole in its structure. The 27Al NMR data are obtained as direct evidence. It is proved that [AlN6] coordination exists in the structure with a chemical shift of 1.6 ppm.The XPS spectra, high resolution transmission electron microscopy and Raman spectra of the new compound are characterized. The differences between the reported "114" type compounds and the crystal structures are summarized and compared.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ174.1

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