High-(p,T) syntheses and characterisation of binary transition metal carbides and nitrides of the period 6 elements with atomic numbers 73-79

重过渡金属的碳化物和氮化物是具有超高熔融温度的超硬和超硬材料的可能候选材料。本文拟研究原子序数为73 ~ 79的第6周期元素在高压高温下的反应生成新的过渡金属碳化物和氮化物。首先关注的是氮化钽和氮化铼以及碳化锇和碳化铱的形成。后续的研究将集中在金碳化物和氮化物的形成上。我们以前的研究已经表明存在一种新的高（p，T）氮化钽。对一种性质不佳的碳化锇晶体结构进行了有争议的讨论。其他碳化物和氮化物的存在至今还没有被研究过。最终目的是了解这类有趣化合物的晶体化学和结构性质关系。在激光加热的金刚石顶砧槽中测定其形成场和稳定场。相将通过粉末x射线衍射，量子力学计算和拉曼光谱来表征。再结晶实验的目的是制备微晶，用微x射线衍射测定结构。为了粉末中子衍射、化学分析和测量反应产物的物理性质，将通过多砧压合成生产大量的样品材料。

Carbides and nitrides of heavy transition metals are possible candidates as ultrahard and ultrastiff materials with ultrahigh melting temperatures. It is proposed here to study the formation of novel transition metal carbides and nitrides of the period 6 elements with atomic numbers from 73 to 79 by reaction of the elements at high pressures and high temperatures. First focus will be on the formation of tantalum and rhenium nitrides, and osmium and iridium carbides. Subsequent studies will concentrate on the formation of gold carbide and nitride. Our previous studies have already indicated the existence of a novel high-(p,T) tantalum nitride. The crystal structure of a poorly characterised osmium carbide is discussed controversially. The existence of the other carbides and nitrides has not even been investigated up to now. The final aim is the understanding of the crystal chemistry and structure-property relations in this interesting class of compounds. The formation and stability fields will be determined in the laser-heated diamond anvil cell. Phases will be characterised by powder X-ray diffraction, quantum-mechanical calculations, and Raman spectroscopy. Recrystallisation experiments are aimed at the production of microcrystals for structure determination by micro X-ray diffraction. Larger quantities of sample material will be produced by multi anvil press syntheses for powder neutron diffraction, chemical analyses, and measurements of the physical properties of the reaction products.