A family of functional oxides of titanosilicates: A2TiSi2O8 (A= Ba, Sr) with temperature insensitive ultrahigh breakdown strength

Discovering new materials with high breakdown strength is of great significance for scientific research and industrial applications. Here, we combine experiments and density functional theory (DFT) calculations to report a systematic study of two titanosilicates - A 2 TiSi 2 O 8 (A = Br, Sr) as a family of functional materials with wide band gaps, ultrahigh breakdown strength, and high thermal stability. The A 2 TiSi 2 O 8 materials possess ultrahigh electric breakdown ( E b > 200 kVmm −1 , at 200 ℃), and good temperature stability (the variation of capacitance 3 %, from −100 to 200 ℃). DFT results show that electrons are likely localized in the Si O and Ti O polyhedrons. The electron difference density map and density of states (DOS) results elucidate the wide band gaps in titanosilicate family due to the strong Si O and Ti O bonds, indicating that the semiconductive behaviors are similar. The temperature-dependent structural evolution (from −100 to 500 ℃) is investigated via in-situ Raman spectroscopy .