Scandate cathodes have garnered significant attention for their exceptional low-temperature, high-current-density emission characteristics. However, their widespread deployment in vacuum electronic devices is currently hindered by stringent vacuum requirements and susceptibility to ion bombardment. To enhance the engineering applicability of scandate cathodes, this study employs first-principles density functional theory (DFT) to model the surface microstructures of strontium (Sr)–scandium (Sc) co-doped systems. Guided by simulation predictions regarding surface elemental ratios, corresponding emission active materials and cathode samples were fabricated. A systematic comparison between theoretical calculations and experimental measurements reveals a critical trade-off: while increasing Sr content enhances structural stability (indicated by lower formation energies), it concurrently increases the work function. Consequently, an optimal Sr doping level of approximately 2 wt% is identified, which significantly improves emission current density without compromising stability. Cathodes fabricated with this optimized composition were tested in a practical electron gun configuration. Results demonstrate that under low-temperature conditions (1000 °C) and wide-pulse operation (2 ms), the cathode achieves an emission current density of 21.57 A/cm2. These findings validate the efficacy of simulation-guided material design and highlight the potential of Sr-doped scandate cathodes for high-power microwave applications.
Li et al. (Sat,) studied this question.