First principles calculations on nitrogen reactivity on tungsten surfaces

Area of Science:

• Surface Science
• Materials Science
• Computational Chemistry

Background:

• Tungsten surfaces are crucial in plasma-based material processing.
• Understanding nitrogen and hydrogen interactions is key for controlling material properties.

Purpose of the Study:

• Investigate nitrogen molecule and hydrogen nitride radical adsorption and dissociation on W{100} and W{110} surfaces.
• Predict nitrogenized species on tungsten after plasma discharge.
• Assess the impact of nitrogen on hydrogen retention and surface reactivity.

Main Methods:

• Spin-polarized gradient-corrected density functional theory (DFT) calculations.
• Modeling of clean, hydrogen-saturated, and nitrogen-saturated tungsten surfaces.
• Analysis of radical dissociation with initial kinetic energies up to 2.5 eV.

Main Results:

• NH, NH2, and NH3 radicals dissociate on tungsten surfaces.
• Dissociation products include surface-incorporated nitrogen atoms and adsorbed protons.
• Nitrogen incorporation significantly reduces hydrogen retention on tungsten surfaces.

Conclusions:

• Nitrided tungsten surfaces exhibit reduced reactivity compared to clean surfaces.
• The W{100} and W{110} surfaces show distinct behaviors in nitrogen and hydrogen interactions.
• Nitrogen plays a critical role in modifying tungsten surface properties during plasma exposure.