Ultrafast preparation of CeNbO4–Mn3O4 ceramics via reactive flash sintering at 300 °C
摘要
The high temperatures and long times required to synthesize CeNbO4 (CN) and Mn3O4 (M) negative temperature coefficient (NTC) ceramics are unfavorable for controlling their grain size and electric properties. Herein, CN and 0.5CeNbO4–0.5Mn3O4 (CN-M) ceramics were rapidly prepared (15–60 s) via the reactive flash sintering (RFS) of CeO2, Nb2O5, and Mn3O4 powders at 300 °C using a 333 V cm−1 electric field and current densities of 50–500 mA·mm−2. A single-phase CN structure was formed under a current density of 100 mA·mm−2 and a flash time of 60 s. However, for CN-M, the complete reaction of Nb2O5 and CeO2 required a 400 mA·mm−2 current density and a flash time greater than 60 s. As the current density and RFS time increased, the density and grain size of the ceramics also increased, influencing their resistivity. The predominant RFS mechanism of these ceramics was identified as the electric field-enhanced diffusion of oxygen interstitials and oxygen vacancies.