Multidimensional structural design of pioneer oxide ceramics with melting points above 3000 °C

Thermal protective materials that remain stable above 3000 °C are crucial for hypersonic vehicles and nuclear fusion systems, yet reported non-radioactive oxides melt below this threshold. Zhou et al. demonstrate a cation-engineering strategy that couples crystallographic symmetry, coordination number, valence electron concentration (VEC), cation radius, and metal-oxygen bonding to raise the melting temperature of fluorite-type oxides. Guided by the above multi-dimensional design framework, Ta-doped HfO₂ is experimentally validated to have a melting point surpassing 3000 °C, which is confirmed as the first non-radioactive oxide with a melting point beyond 3000 °C. This perspective distills the underlying symmetry-VEC-bonding design principles and discusses how they can guide the discovery and engineering integration of ultrahigh-temperature oxide ceramics.