Comparative analysis of Ti₃SiC₂ and associated compounds using x-ray diffraction and x-ray photoelectron spectroscopy

Ti₃SiC₂ exhibits a unique combination of ceramic and metallic properties suitable for both electrical and mechanical application. With high-temperature stability, high electrical and thermal conductivity and resistance to oxidation, Ti₃SiC₂ has proven promising as a contact layer for high power SiC semiconductors. However, until recently, synthesis of this material has proven difficult without appreciable quantities (<2 vol{%}) of impurity phases, namely TiC_1-x and Ti₅Si₃C_x. As such, many properties of this compound are as yet unknown. In this paper, a comparable analysis of Ti₃SiC₂ and associated compounds, TiC and Ti₅Si₃C_x has been performed using both x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Assessing impurity sensitivities for each technique, XRD was shown to readily identify impurities of TiC and Ti₅Si₃C_x within Ti₃SiC₂ at <2 wt{%}. Although XPS could not independently resolve these impurities, its use resulted in the detection of a complex oxide structure on Ti₃SiC₂. It was speculated that it was composed of mixed C-Ti-C-O and Si-Ti-C-O bond chemistries. In a comparison of TiC, Ti₅Si₃C_x and Ti₃SiC₂, differences in oxide states suggest that oxidation is chemically dissimilar for all the three compounds. However, upon etching, the binding energies of Ti₃SiC₂ and Ti₅Si₃C_x were shown to be very similar. It may be concluded that a concurrent analysis of both XRD and XPS was essential for identifying the overall surface chemistry of Ti₃SiC₂.