Fast ion transport for synthesis and stabilization of β-Zn₄Sb₃

Mobile ion-enabled phenomena make β-Zn₄Sb₃ a promising material in terms of the re-entry phase instability behavior, mixed electronic ionic conduction, and thermoelectric performance. Here, we utilize the fast Zn²⁺ migration under a sawtooth waveform electric field and a dynamical growth of 3-dimensional ionic conduction network to achieve ultra-fast synthesis of β-Zn₄Sb₃. Moreover, the interplay between the mobile ions, electric field, and temperature field gives rise to exquisite core-shell crystalline-amorphous microstructures that self-adaptively stabilize β-Zn₄Sb₃. Doping Cd or Ge on the Zn site as steric hindrance further stabilizes β-Zn₄Sb₃ by restricting long-range Zn²⁺ migration and extends the operation temperature range of high thermoelectric performance. These results provide insight into the development of mixed-conduction thermoelectric materials, batteries, and other functional materials.