Theoretical insights into the key properties of Ce_1−xM_xB₆ (M = Ba, Sr, Ca) as promising plasma grid materials for N-NBI systems

This study adopts first-principles computational approaches to explore the structural, electronic, mechanical, surface work function and thermodynamic behaviors of Ce_1−xM_xB₆ (M = Ba, Sr, Ca) composites with doping ratios x ranging from 0 to 1 (0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1). Core properties including lattice constants, elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, surface work function, Debye temperature, and melting point are comprehensively examined. The findings reveal that doping typically results in a decline in the surface work function, with Ce₀.₃₇₅Ba₀.₆₂₅B₆ attaining the lowest value of 1.47 eV. All Ce_1−xM_xB₆ composites satisfy the mechanical stability criteria and exhibit brittle features (B/G < 1.75), with Ba doping enhancing shear resistance and Ca doping slightly improving ductility. Thermodynamic analysis demonstrates that the melting points of all composites exceed 2000 K, confirming their excellent thermal stability. These results offer valuable theoretical references for the development of cesium-free electrode materials suitable for plasma-facing applications in neutral beam injection (NBI) systems.