Lead-free (Ag,K)NbO₃ materials for high-performance explosive energy conversion

Explosive energy conversion materials with extremely rapid response times have broad and growing applications in energy, medical, defense, and mining areas. Research into the underlying mechanisms and the search for new candidate materials in this field are so limited that environment-unfriendly Pb(Zr,Ti)O₃ still dominates after half a century. Here, we report the discovery of a previously undiscovered, lead-free (Ag_0.935K_0.065)NbO₃ material, which possesses a record-high energy storage density of 5.401 J/g, enabling a pulse current ~ 22 A within 1.8 microseconds. It also exhibits excellent temperature stability up to 150°C. Various in situ experimental and theoretical investigations reveal the mechanism underlying this explosive energy conversion can be attributed to a pressure-induced octahedral tilt change from a ^- a ^- c ⁺ to a ^- a ^- c ^-/a ^- a ^- c ⁺, in accordance with an irreversible pressure-driven ferroelectric-antiferroelectric phase transition. This work provides a high performance alternative to Pb(Zr,Ti)O₃ and also guidance for the further development of new materials and devices for explosive energy conversion.