TY - JOUR
T1 - First principles phase diagram calculation for the 2D TMD system WS2−WTe2
AU - Burton, B. P.
AU - Sluiter, M. H.F.
N1 - Accepted Author Manuscript
PY - 2018
Y1 - 2018
N2 - First principles phase diagram calculations, that included van der Waals interactions, were performed for the bulk transition metal dichalcogenide system (1−X)·WS2−(X)·WTe2. To obtain a converged phase diagram, a series of cluster expansion calculations were performed with increasing numbers of structural energies, (Nstr) up to Nstr=435, used to fit the cluster expansion Hamiltonian. All calculated formation energies are positive and all ground-state analyses predict that formation energies for supercells with 16 or fewer anion sites are positive; but when 150⪅Nstr⪅376, false ordered ground-states are predicted. With Nstr≥399, only a miscibility gap is predicted, but one with dramatic asymmetry opposite to what one expects from size-effect considerations; i.e. the calculations predict more solubility on the small-ion S-rich side of the diagram and less on the large-ion Te-rich side. This occurs because S-rich low-energy metastable ordered configurations have lower energies than their Te-rich counterparts which suggests that elastic relaxation effects are not dominant for the shape of the miscibility gap.
AB - First principles phase diagram calculations, that included van der Waals interactions, were performed for the bulk transition metal dichalcogenide system (1−X)·WS2−(X)·WTe2. To obtain a converged phase diagram, a series of cluster expansion calculations were performed with increasing numbers of structural energies, (Nstr) up to Nstr=435, used to fit the cluster expansion Hamiltonian. All calculated formation energies are positive and all ground-state analyses predict that formation energies for supercells with 16 or fewer anion sites are positive; but when 150⪅Nstr⪅376, false ordered ground-states are predicted. With Nstr≥399, only a miscibility gap is predicted, but one with dramatic asymmetry opposite to what one expects from size-effect considerations; i.e. the calculations predict more solubility on the small-ion S-rich side of the diagram and less on the large-ion Te-rich side. This occurs because S-rich low-energy metastable ordered configurations have lower energies than their Te-rich counterparts which suggests that elastic relaxation effects are not dominant for the shape of the miscibility gap.
KW - First principles
KW - Phase diagram calculation
KW - TMD
KW - Transition metal dichalcogenide
KW - Van der Waals
KW - WS2−WTe2
UR - http://resolver.tudelft.nl/uuid:0d33360e-69f5-455e-9dcf-431b3b51ad6a
UR - http://www.scopus.com/inward/record.url?scp=85054012661&partnerID=8YFLogxK
U2 - 10.1016/j.calphad.2018.08.001
DO - 10.1016/j.calphad.2018.08.001
M3 - Article
AN - SCOPUS:85054012661
SN - 0364-5916
VL - 63
SP - 142
EP - 147
JO - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry
JF - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry
ER -