Combined experimental and first-principles studies of structural and physical properties of β-Ti3SiC2

MAX phase materials have shown a series of interesting, even sometimes unusual, properties and exhibited combined attributes of both metals and ceramics, which are due to their “layered ternary transition metal carbides” structures. In the process of studying the multistage phase transformation of 312-MAX phase materials, we found that there were some confusions and mistakes when describing the crystal structures of the β-phase in the existing literature. In order to clarify their structural and physical properties, the β-phase Ti3SiC2 materials have been prepared by using 500 keV He2+-ion irradiation-induced phase transformation and examined by first-principles calculations and Rietveld analysis of grazing incidence x-ray diffraction patterns. Two accurate descriptions of the β-Ti3SiC2 structure are given here. In order to avoid confusion again, it is recommended to use one of the two descriptions uniformly. In addition, some physical properties parameters of β-Ti3SiC2 have been calculated and compared, which also confirmed the correctness of the structure description. Finally, the vacancy formation energies of β-Ti3SiC2 have been predicted and discussed in detail from the points of phase stability and transformation for the first time.