OsO4

Osmium tetroxide (OsO₄) is a highly toxic transition metal oxide ceramic compound characterized by its extreme density and significant stiffness. While primarily known as a powerful oxidizing agent in organic chemistry and histology (as a biological stain), OsO₄ has limited structural engineering applications due to its toxicity, volatility at moderate temperatures, and the specialized handling requirements it demands. Its use in materials engineering is restricted to niche applications where its unique chemical properties—rather than mechanical performance—are the critical factor.