Density-functional-theory predictions of mechanical behaviour and thermal properties as well as experimental hardness of the Ga-bilayer Mo2Ga2C

Autor: Xinxin Qi, Weilong Yin, Sen Jin, Aiguo Zhou, Xiaodong He, Guangping Song, Yongting Zheng, Yuelei Bai
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Journal of Advanced Ceramics, Vol 11, Iss 2, Pp 273-282 (2022)
Druh dokumentu: article
ISSN: 2226-4108
2227-8508
DOI: 10.1007/s40145-021-0531-9
Popis: Abstract Mo2Ga2C is a new MAX phase with a stacking Ga-bilayer as well as possible unusual properties. To understand this unique MAX phase structure and promote possible future applications, the structure, chemical bonding, and mechanical and thermodynamic properties of Mo2Ga2C were investigated by first-principles. Using the “bond stiffness” model, the strongest covalent bonding (1162 GPa) was formed between Mo and C atoms in Mo2Ga2C, while the weakest Ga-Ga (389 GPa) bonding was formed between two Ga-atomic layers, different from other typical MAX phases. The ratio of the bond stiffness of the weakest bond to the strongest bond (0.33) was lower than 1/2, indicating the high damage tolerance and fracture toughness of Mo2Ga2C, which was confirmed by indentation without any cracks. The high-temperature heat capacity and thermal expansion of Mo2Ga2C were calculated in the framework of quasi-harmonic approximation from 0 to 1300 K. Because of the metal-like electronic structure, the electronic excitation contribution became more significant with increasing temperature above 300 K.
Databáze: Directory of Open Access Journals