Revisiting the melting curves of vanadium and niobium metals under pressure

• Published in: Vacuum Vol. 206; p. 111507
• Main Authors: Hieu, Ho Khac, Hoang, Hai, Hanh, Pham Thi Minh, Hai, Tran Thi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022
• Subjects: High pressure; Lindemann criterion; Melting curves; Niobium; Statistical moment method; Vanadium; Melting curves; Lindemann criterion; Niobium; Statistical moment method; Vanadium; High pressure
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2022.111507

The Lindemann criterion is adjusted to revisit melting curves of vanadium and niobium metals under pressure thanks to the statistical moment method (SMM) in statistical mechanics. The equation-of-state and atomic mean-square displacement in SMM approach are applied to implement numerical calculations for vanadium and niobium metals up to 250 GPa and 150 GPa, respectively. The obtained theoretical melting curves are compared with results of previous experiments and molecular dynamics (MD) simulations where possible to check the theory. We expose that our theoretical melting line of vanadium is overall in good agreement with previous results determined by in situ X-ray diffraction (XRD) and diffuse scattering signals using synchrotron XRD together with shock experiments up to pressure 250GPa. For niobium, our melting curve follows very well with those of recent experimental XRD data as well as ab initio Z method up to 124 GPa. However, we also observe the difference of classical MD simulation results from SMM calculations at pressure below 2.5 GPa. This research enriches the high-pressure melting point database as well as provides a relatively simple approach with low computational cost to estimate high-pressure melting points of materials. •Melting curves of V and Nb are investigated based on the statistical moment method.•Lindemann criterion is adjusted to study melting points of V, Nb up to 250 GPa and 150 GPa.•Theoretical V melting line goes along with recent XRD measurements up to 250 GPa.•Our Nb melting curve coincides with XRD data and ab initio Z method up to 124 GPa.