Calculated pressure induced electronic and structural transitions in transition metals

Yıl 2014, , 9 - 11, 23.06.2014

Hamdi Dagıstanlı

https://doi.org/10.17678/beujst.86268

Öz

The partial occupation numbers and the density of states (DOS) at the Fermi level were calculated as a function of reduced atomic volume for transition metals by employing the linear-muffin-tin-orbital (LMTO) method. The pressure induced electronic transitions from sp states to d states are confirmed for early metals; and for the heavier elements, on the otherhand, pressure induced d→p electronic transitions were found. By means of the abrupt changes obtained in the p-DOS values, good agreement with regard to experiment were found in predicting the structural phase transition volumes and it is concluded that the phase stability of transition metals under pressure is related to the characteristic shape of DOS near the Fermi level.

Anahtar Kelimeler

Pressure, occupation numbers, structural phase transitions, transition metals

Kaynakça

• Ahuja R, Söderlind P, Wills JM, Johansson B, Eriksson O (1994). Electronic structure of plantinum at ultra high pressure. High Pres Res 12,161-170.
• Andersen OK (1975). Linear methods in Band Theory. Phys Rev B 12, 3060-3083.
• Cazorla C, Alfe D, Gillan M (2008). Zero temperature generalized phase diagram of the 4d transitions metals under pressure. Phys Rev B 77, 224103 1-11.
• Hafner J, Hobbs D (2003). Understanding the complex metallic element MN I. Crystalline and noncollinear structure of α-Mn. Phys Rev B 68, 014407-014408.
• McMahan AK, Moriarty JA (1983). Structural phase stability in third-period simple metals. Phys Rev B 27, 3235-3251.
• Melsen J, Wills J M, Johansson B, Eriksson O (1993). Prediction of a bcc structure in compressed yttrium. Phys Rev B 48, 15574-15577.
• Mutlu RH (1995). Structural phase transitions and specific heat coefficients of alkaline earth metals. J Phys Cond Mat 7, 1283-1286.
• Perdew J P, Chevary J A, Vosko S H, Jackson K A, Pederson MR, Singh DJ, Fiolhais C (1992). Atoms, molecules, solids and surfaces: Applications of the generalized gradient approximation for exchange and correlation. Phys Rev B 46, 6671-6678.
• Skriver HL (1984). The LMTO Method, Springer, New York, 281 pp, ISBN: 0387115196.
• Skriver HL (1985). Crystal structure from one-electron theory. Phys Rev B 31, 1909-1923.
• Verma AK, Modak P, Rao RS, Godwal BK, Jeanloz R (2007). High pressure phases of titanium: First principles calculations. Phys Rev B 75, 014109 1-5.
• Vohra YK, Spencer PT (2001). Novel γ-phase of Titanium metal at Megabar pressures. Phys Rev Lett 86, 3068- 3071.
• Vosko SH, Wilk L, Nusair M (1980). Accurate spin dependent electron of liquid correlation energies for local spin density calculations. Can J Phys 58, 1200- 1211.
• Xia H, Parthasarathy G, Luo H, Vohra YK, Ruoff AL (1990). Crystal structures of group IVa metals at ultra high pressures. Phys Rev B 42, 6736-6738.
• Zhao YC, Porsch F, Holzapfel WB (1996). Evidence fort he occurence of a prototype structure in Sc under pressure. Phys Rev B 54, 9715-9720.