Ab initio molecular dynamics simulation of threshold displacement energies and defect formation energies in Y4Zr3O12

Abstract

Ab initio molecular dynamics simulations using VASP was employed to calculate threshold displacement energies and defect formation energies of Y4Zr3O12 δ-phase, which is the most commonly found phase in newly developed Zr and Al-containing ODS steels. The Threshold displacement energy (Ed) values are determined to be 28 eV for Zr3a PKA along [111] direction, 40 eV for Zr18f atoms along [111] direction and 50 eV for Y recoils along [110] direction.Minimum Ed values for O and O' atoms are 13 eV and 16 eV respectively. The displacement energies of anions are much smaller compared to cations, thus suggesting that anion disorder is more probable than cation disorder. All directions except the direction in which inherent structural vacancies are aligned, cations tend to occupy another cation site. The threshold displacement energies are larger than that of Y2Ti2O7, the conventional precipitates in Ti containing ODS steels. Due to the partial occupancy of Y and Zr in the 18f position, the antisite formation energy is negligibly small, and it may help the structure to withstand more disorder upon irradiation. These results convey that Zr/Al ODS alloys, which have better corrosion resistance properties compared to the conventional Ti-ODS alloys, may also possess superior radiation resistance.

Interfacial strain relief by periodic dislocation doublets emerging from rotationally related orientation relationships of Y4Zr3O12 dispersions in ferrite matrix

“…space group. It is the most stable oxide in the Y-Zr-O system [28] and can be represented in rhombohedral as well as hexagonal axes. The lattice parameters in hexagonal axes are: a=9.738 and c=9.115 (ICDD : 01-077-0743, [29]).…”

“…This explicit precipitatematrix correlation in atomic scale is a conclusive evidence to the fact that the Y 2 O 3 is dissolving during the milling and it is re-precipitating as Y-Zr-O nuclei during hot-consolidation in an energetically preferred manner. The low formation energy favours Y 4 Zr 3 O 12 than other structures in Y-Zr-O system [28,37]. Existence of a few random orientations with high order zone axes might be due to:(i) loss of coherency in the growth phase as the strain energy overweighs the interfacial energy [30] or (ii) they nucleate with various orientation relationships owing to the non-equilibrium nature of the ball milling process [38].…”

First‐Principles Molecular Dynamics Study of the Threshold Displacement Energy in LiFe5O8

“…According to all the literature, the TDE shows great dependence on the crystallographic direction and lattice atom type. [ 21,22,35–37 ] A weighted average value is often used as a parameter in some simulation models. [ 38 ] The unit cell of LFO contains five nonequivalent atoms, [ 32 ] two O atoms (O I and O II ), two Fe atoms (Fe Tetra and Fe Oct ), and one Li atom.…”

Correlation between anion defects and ion beam induced luminescence in Y4Zr3O12

“…SRIM simulations (Figure 1 of supplementary material) have been carried out before ion irradiation experiments according to which the projected range of He + ions in Y 4 Zr 3 O 12 is ∼ 415 nm and the number of oxygen vacancies per ion-Å are ∼ 75% higher than the combined number of Zr and Y vacancies. Previous ab initio molecular dynamics simulations also show that the displacement energy (E d ) values of cations in Y 4 Zr 3 O 12 is much higher than that of anions forecasting increased anionic vacancy related defect formation during irradiation [7].…”

“…The radiation resistance is achieved by the order-todisorder transformations to disordered fluorite structure which delays amorphization [4][5][6]. The lower values of defect reaction pair energy (the sum of cation antisite formation energy and anion Frenkel pair formation energy) of δ-phase compounds point to their superior radiation tolerance compared to pyrochlores [7,8]. Existing literature on ion irradiated δ-phase compounds report either a partial or full transformation from the parent rhombohedral phase to the disordered fluorite phase and delayed amorphization upon swift heavy ion irradiation and low energy ion irradiation [5,[8][9][10].…”