LAUSR

Abstract Layer-structured calcium silicide (CaSi2) is prepared using a fast and clean combustion synthesis (CS) method, employing silica as the silicon source. The CS process was characterized by the occurrence of an ignition reaction at 510 °C, leading to the formation of CaO, CaSi2, Ca14Si19, and Ca3SiO5 which is converted into CaSi2 with minor amounts of Si after an acid treatment. The mechanism involved in the CS process is discussed. The structure and microstructure of the CS-CaSi2 is characterized and compared with the commercial CaSi2, and the outcomes are discussed based on the Ca-Si binary phase diagram. In comparison with the latter, the CS-CaSi2 has a considerably greater purity, with loosely stacked structure, providing a surface area of around 43 m2 g−1. The thermal analysis of the CS-CaSi2 is conducted under high purity argon and air flow of 100 mL min−1, comprising differential scanning calorimetry (DSC) and thermal gravimetric (TG) analysis. The analysis conducted under argon provides evidence for the occurrence of the melting event at 1037 °C. Under air, the material is almost stable below 800 °C, while the oxidation is detected at higher temperatures. The oxidation peak of the material is realized from the corresponding DSC thermogram to take place at 1028 °C. The oxidation event is suggested to occur through two stages. At the first stage (T