High-(P,T) properties of tantalum and titanium carbides and nitrides

利用可加热的Paris-Edinburgh型晶胞的中子衍射实验和量子力学分子动力学模拟，研究了TiC_1-xN_x(0&lt；x&lt；1)和Ta类似物对高(P，T)条件的结构响应。热力学性质，包括熔化行为，将通过激光加热的钻石砧座实验获得。熔化温度作为(P，T)的函数将通过目视原位观察获得，而其他热力学性质将由非原位X射线衍射获得。激光加热的金刚石压腔实验也将被用来探索在高压下诱导自蔓延高温合成(SHS)的可能性。在DAC中成功演示SHS将对耐火化合物的高温研究具有重要意义，并将有助于确定在极端条件下使用激光加热DAC作为反应室。从中子衍射实验中确定对高(P，T)条件的结构响应将被用来评估量子力学MD在这种极端条件下的适用性，并有助于更深入地理解非常大的化合物家族的基本晶体化学关系

We propose to study the structural response of TiC1-xNx (0 < x < 1) and the Ta-analogues to high (P,T) conditions by neutron diffraction experiments employing heatable¿ Paris-Edinburgh¿-type cells and quantum mechanical molecular dynamics simulations. Thermodynamic properties, including the melting behaviour, will be obtained by laser-heated diamond anvil cell experiments. Melting temperatures as a function of (P,T) will be obtained by visual in situ observation, while other thermodynamic properties will be derived from ex situ x-ray diffraction. Laser heated diamond anvil cell experiments will also be used to explore the possibility of inducing a self-propagating high-temperature synthesis (SHS) at high pressures. A successful demonstration of a SHS in a DAC would have important implications for high temperature studies of refractory compounds and would help to establish the use of a laser-heated DAC as a reaction chamber at extreme conditions. The determination of the structural response to high (P,T)-conditions from the neutron diffraction experiments would be used to evaluate the applicability of quantum mechanical MD to such extreme conditions, and would contribute to a deeper understanding of fundamental crystal chemical relations for a very large family of compounds