IVB族金属氮化物在压力下的新结构预测与性质研究

The group IVB transition metal nitrides are widely used for cutting coating materials, ultra-wear-resistant materials and thermal barrier coating materials, thanks to their excellent properties such as high melting point, excellent mechanical properties and prominent corrosion resistance. However, most of theoretical studies are focus on the structure and properties of the group IVB transition metal nitrides under atmospheric pressure. The study of properties under high pressure for solid materials is an important way to discover novel hard coating materials and superhard materials. Using first-principles calculations based on density functional theory and the evolutionary algorithm, this study will systematically explore the new stable components and new stable structures of group IVB transition metal nitrides under different pressures. Furthermore, we will study the mechanical properties, thermodynamic properties, optic properties and oxidation resistance of these new structures, as well as the mechanical properties and oxidation resistance of their corresponding surface structures, to find novel group IVB transition metal nitrides with excellent physical properties or chemical properties. Moreover, we try to unveil the relationship between the microstructure (electronic structure and bonding characteristics) and the macroscopic properties (geometric structure, mechanical properties and thermodynamic stability) for group IVB transition metal nitrides. This study provides theoretical reference and guidance for the practical synthesis and application of novel group IVB transition metal nitrides, especially for the application of novel hard coating materials and novel superhard materials.

IVB族金属氮化物具有高熔点、优异的力学性能和出色的耐腐蚀性能等特性，目前被广泛用作切割涂层材料、超耐磨材料和热障涂层材料。但是，多数理论研究集中在探索IVB族金属氮化物在常压下的结构与性质，而高压下的材料物性研究是发现新的硬质涂层材料、超硬材料的重要途径。我们将结合遗传演化算法和基于密度泛函理论的第一原理计算系统地搜索IVB族金属氮化物在不同压力下新的稳定组分和稳定结构，分析新结构的力学、热力学和光学等性质及其相应特征界面结构的力学性质和抗氧化性，挖掘出具有优异物理化学性质的新型IVB族金属氮化物，并探索新结构的微观结构（电子结构与键合特征）与宏观物性（几何构型、力学性质以及热力学稳定性）之间的关联及其物理机制。这个研究将对基于IVB族金属氮化物的新型材料（尤其是硬质涂层材料和超硬材料）的合成与应用提供重要的理论基础与参考。

IVB族金属氮化物具有高熔点、优异的力学性能和出色的耐腐蚀性能等特性，目前被广泛用作切割涂层材料、超耐磨材料和热障涂层材料。但是，多数理论研究集中在探索IVB族金属氮化物在常压下的结构与性质，而高压下的材料物性研究是发现新的硬质涂层材料、超硬材料的重要途径。本项目结合遗传演化算法和基于密度泛函理论的第一原理计算在IVB族过渡金属二氮化物中预测出三种高压新结构（Cmcm，P21/c-α, P21/c-β），其中P21/c-α-TMN2和P21/c-β-TMN2表现出优异的力学性质，具有硬质涂层方面的潜在应用价值。其次，在富金属体系Zr2N中找到五个新型高压结构（P4/nmm, I4/mcm, P21/m, P¯3 m1 和C2/m），探索了不同相的力学性质与微观电子结构之间的关联，并从构型和原子尺度研究了具有相同化学成分比的不同Zr2N相的力学性质的差异及其背后物理机制。最后，系统全面地搜索了IVB族金属氮化物在不同压力下（0-150GPa）所有稳定组分和稳定结构，获得了Ti-N、Zr-N和Hf-N在压力下的完整相图。本项目将有助于全面了解IVB族过渡金属氮化物，并对基于IVB族金属氮化物的新型硬质涂层材料的合成与应用提供重要的理论基础与参考。