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

• 作者: Xinxin QI Weilong YIN Sen JIN Aiguo ZHOU Xiaodong HE Guangping SONG Yongting ZHENG Yuelei BAI
• 来源期刊: 先进陶瓷（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: Research Article
• 页码范围: 273-282
• 页数: 10页
• 语种: 英文

摘要

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.