The System Si-Al-O-N at Extreme Pressures: A Synthetic and Computational Route to Novel Materials?

我们的主要目标将是在系统Si <$Al <$O <$N中定位潜在的新的高密度相，特别是在子系统Si 2N 2 O中。. .Al2O3和Si 3 N4。. . AlN。为了提供坚实的基础，我们将根据我们自己的初步工作，使用多砧技术合成<$-Si 3 N4和岩盐型AlN（rs-AlN）的大单晶。大晶体将使我们能够非常精确地计算物理性质（弹性性质、电子结构、振动光谱），为理论结果提供严格的检验。三进制（Si？奥N）和四元（Si？阿尔乌奥N）相，然后使用由冲击波合成补充的静态高压技术进行探测，以产生更大量的材料。这些产品将进行全面的表征，包括X射线，红外显微镜和显微拉曼光谱，分析高分辨率TEM，EPMA，西姆斯/SNMS和固态NMR。这些系统的理论研究将基于第一性原理密度泛函理论计算。该项目将为Si <$Al <$O <$N系统在高压和高温下的基本未知相行为提供基本见解。

Our main goal will be to locate potential new high density phases within the system Si¿Al¿O¿N in particular in the subsystems Si2N2O. . .Al2O3 and Si3N4. . .AlN. In order to provide a firm basis we will synthesise large single crystals of ¿-Si3N4 and rocksalt type AlN (rs-AlN) based on our own preliminary work using multi-anvil techniques. Large crystals will enable us to characterise physical properties (elastic properties, electronic structure, vibrational spectra) very accurately, providing a stringent test for theoretical results. Existence of ternary (Si¿O¿N) and quarternary (Si¿Al¿O¿N) phases will then be probed using static high pressure techniques supplemented by shock wave synthesis in order to produce larger amounts of material. The products will be subjected to thorough characterisation including X-ray, IR-microscopy and micro-Raman spectroscopy, analytical high resolution TEM, EPMA, SIMS/SNMS and solid state NMR. Theoretical investigations on these systems will be based on first-principles density-functional theory calculations. The project will provide fundamental insight into the largely unknown phase behaviour of the system Si¿Al¿O¿N at high pressures and high temperatures.