Crystal Structure and Theoretical Elastic Property of a New Ternary Ceramic HfAl_4C_4

摘要

HfAl_4C_4, a new ternary aluminum carbide, was discovered and its crystal structure was determined by a combination of X-ray diffraction, transmission electron microscopy, and first-principles calculations. The crystal structure is trigonal belonging to the P3m1 space group. The refined lattice constants are a = 0.3308 nm, c = 2.190 nm. First-principles method was used to calculate the theoretical second-order elastic constants, bulk modulus, shear modulus, and the Young's modulus of HfAl_4C_4. It shows that HfAl_4C_4 has relatively high elastic stiffness.