Beryllium, tungsten and their alloys Be2W and Be12W: Surface defect energetics from density functional theory calculations

Assessment of the literature about Be-W mixed material layer formation in the fusion reactor environment

“…Baldwin et al claim that evaporation leads to loss of beryllium when the surface temperature increases (1150 K), although this does not appear consistent with recent atomistic modeling. These atomistic calculations involved DFT, molecular statics (MS) and molecular dynamics (MD) based on semi-empirical potentials [3,[20][21][22], and indicate that the surface binding energies for beryllium on beryllium or on Be-W intermetallics are in excess of 3 eV, which make evaporation rates seemingly too low at temperatures below 1300 K. Therefore, we conclude that other beryllium removal mechanisms must be at play, such as thermally enhanced sputtering or physically assisted chemical sputtering, although neither of these two mechanisms would occur during thermal deposition experiments.…”

“…There are a limited number of first principle based atomistic calculations available in the literature [3,16,22,[36][37][38][39] to understand the Be-W thermodynamics and surface interactions. There are also a number of molecular statics and dynamics simulations available in the literature [16,21,22,[40][41][42][43][44][45][46] to understand the kinetics of beryllium-tungsten intermetallic layer formation and growth.…”

“…There are a limited number of first principle based atomistic calculations available in the literature [3,16,22,[36][37][38][39] to understand the Be-W thermodynamics and surface interactions. There are also a number of molecular statics and dynamics simulations available in the literature [16,21,22,[40][41][42][43][44][45][46] to understand the kinetics of beryllium-tungsten intermetallic layer formation and growth. Chen's latest work [47], as well as Bjorkas' and Lasa's simulations focused on erosion and mixing through energetic ion implantation: irradiation of tungsten by beryllium, of mixed Be-W by deuterium, and of tungsten by D-Be.…”

“…Chen and coworkers have also used DFT to extend the energy calculations of tungsten and beryllium adsorption on a wider range of surface orientations. In particular, they examined Be(0001), Be(1120 ¯), Be(1121 ¯), W(001), W(110), W(111), Be 2 W(001), Be 2 W(110), Be 2 W(111), Be 12 W(001), Be 12 W(110), and Be 12 W(111) orientations [22]. The beryllium adsorption energy on different beryllium surfaces is within a range of 2-2.7 eV whereas on intermetallic surfaces it varies between 3 and 4.3 eV (adsorption energy calculated as the difference between the formation energies of a surface-adsorbed beryllium atom and a hexagonal closed packed beryllium atom).…”

Поверхностное соединение при адсорбции Be на W(100): определение абсолютной концентрации и свойства

“…В литературе имеется ряд работ, посвященных адсорбционной системе Be−W [9][10][11][12][13][14]. В экспериментальных работах [9,12,14] методом рентгеновской фотоэлектронной спектроскопии исследуются термостабильность нанометровых бериллиевых пленок и образование объемных соединений.…”