Synthesis, crystallographic structure and thermodynamic properties of T2-Al2MgC2

• Published in: Journal of solid state chemistry Vol. 273; pp. 150 - 157
• Main Authors: Deffrennes, Guillaume, Gardiola, Bruno, Jeanneau, Erwann, Mikaelian, Georges, Benigni, Pierre, Pasturel, Alain, Pisch, Alexander, Andrieux, Jérôme, Dezellus, Olivier
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.05.2019; Elsevier
• Subjects: Al-C-Mg; Chemical Sciences; Crystal structure; Density functional theory (DFT); Electronic structure; Material chemistry; Phonons; T2-Al2MgC2; Thermodynamic properties; T2-Al2MgC2; Electronic structure; Phonons; Thermodynamic properties; Density functional theory (DFT); Al-C-Mg; Crystal structure; Density Functional Theory (DFT)
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2019.02.039

T2-Al2MgC2 was synthesized from the elements in a Mg-Al melt at 1000 °C using sealed Ta crucibles. Single crystals of T2-Al2MgC2 were extracted by evaporating the Mg-Al matrix. The crystal structure of T2-Al2MgC2 was refined for the first time on the basis of single-crystal X-ray diffraction. The crystal is trigonal (space group P-3m1, Z = 1) with lattice parameters of a = 3.3767(11) Å, c = 5.807(2) Å and V = 57.34(5) Å3. Based on the refined crystal structure, DFT calculations were conducted to evaluate the thermodynamic properties and the electronic structure of the phase. The heat of formation of T2-Al2MgC2 was calculated to be −23.6 kJ/mol of atoms at 298 K. The heat capacity of T2-Al2MgC2 was measured by DSC from 300 to 871 K and calculated by DFT from 0 to 1000 K. Based on the calculated heat capacity, the entropy of formation of the phase at 298 K was determined to be 70.0 J/mol/K. The band structure and the electronic density of state of T2-Al2MgC2 was calculated leading to an indirect band gap value of 1.73 eV. T2-Al2MgC2 was synthesized from the elements in a Mg-Al melt at 1000 °C. Single crystals of T2-Al2MgC2 were extracted by evaporating the Mg-Al matrix and the crystal structure was refined for the first time on the basis of single-crystal X-ray diffraction. DFT calculations were conducted to evaluate the thermodynamic properties and the electronic structure of the phase and the heat capacity of T2-Al2MgC2 was also measured by DSC from 300 to 871 K. [Display omitted] •Al2MgC2 was synthesized in liquid Mg at 1000 °C using sealed Ta crucibles.•Crystal structure was refined on the basis of single-crystal X-ray diffraction.•Density Functional Theory calculations were conducted using the SCAN functional.•Thermodynamic properties of Al2MgC2 were predicted from 0 to 1000 K and measured by DSC.•The indirect band gap was estimated to be 1.73 eV and the DOS was calculated.