Thermodynamic properties of the alkali metals at high temperatures and high pressures using mean-field potential model

2005 ◽  
Vol 66 (5) ◽  
pp. 797-808 ◽  
Author(s):  
N.K. Bhatt ◽  
P.R. Vyas ◽  
A.R. Jani ◽  
V.B. Gohel
Keyword(s):  
Thermodynamic Properties ◽  
High Temperatures ◽  
Alkali Metals ◽  
High Pressures ◽  
Potential Model ◽  
Mean Field ◽  
Field Potential ◽  
Mean Field Potential

Mean-field potential approach for thermodynamic properties of lanthanide: Europium as a prototype

2018 ◽  
Vol 32 (06) ◽  
pp. 1850065 ◽  
Author(s):  
Priyank Kumar ◽  
N. K. Bhatt ◽  
P. R. Vyas ◽  
V. B. Gohel
Keyword(s):  
Thermodynamic Properties ◽  
Mean Field ◽  
Great Influence ◽  
Field Potential ◽  
Extreme Environment ◽  
Condensed State ◽  
Present Scheme ◽  
Cold Energy ◽  
Divalent Lanthanide ◽  
Mean Field Potential

In the present paper, a simple conjunction scheme [mean-field potential (MFP) + local pseudopotential] is used to study the thermodynamic properties of divalent lanthanide europium (Eu) at extreme environment. Present study has been carried out due to the fact that divalent nature of Eu arises because of stable half-filled 4f-shell at ambient condition, which has great influence on the thermodynamic properties at extreme environment. Due to such electronic structure, it is different from remaining lanthanides having incomplete 4f-shell. The presently computed results of thermodynamic properties of Eu are in good agreement with the experimental results. Looking to such success, it seems that the concept of MFP approach is successful to account contribution due to nuclear motion to the total Helmholtz free energy at finite temperatures and pressure-induced inter-band transfer of electrons for condensed state of matter. The local pseudopotential is used to evaluate cold energy and hence MFP accounts the s–p–d–f hybridization properly. Looking to the reliability and transferability along with its computational and conceptual simplicity, we would like to extend the present scheme for the study of thermodynamic properties of remaining lanthanides and actinides at extreme environment.

THERMODYNAMIC PROPERTIES OF 4f- AND 5f-SHELL METALS AT FINITE TEMPERATURES: MEAN-FIELD POTENTIAL APPROACH IN CONJUNCTION WITH LOCAL PSEUDOPOTENTIAL

2005 ◽  
Vol 19 (06) ◽  
pp. 999-1016 ◽  
Author(s):  
N. K. BHATT ◽  
P. R. VYAS ◽  
A. R. JANI ◽  
V. B. GOHEL
Keyword(s):  
Thermodynamic Properties ◽  
Mean Field ◽  
Field Potential ◽  
Static Compression ◽  
Potential Approach ◽  
Specific Heats ◽  
Shock Hugoniot ◽  
Volume Relation ◽  
Experimental Findings ◽  
Mean Field Potential

The thermodynamic properties of 4f- and 5f-shell metals have been studied at high temperatures using mean-field potential approach. The MFP seen by the lattice ion is constructed in terms of the total energy-volume relation using local pseudopotentials due to Pandya et al. [Physica B 307, 138 (2001)]. We have calculated static compression, shock-wave compression, volume thermal expansion, isothermal and adiabatic bulk moduli ( B T and B S ), specific heats ( C V and C P ), thermodynamic Grüneisen parameter (γ th ), anharmonic contribution to the specific heat and temperature along shock Hugoniot for 4f (γ- Ce )- and 5f (fcc-Th) -shell metals. The results are well compared with the other theoretical and experimental findings, which ensure the use of pseudopotentials for studying thermodynamic properties at higher temperatures in case of lanthanides and actinides.

Liquid metals and semiconductors under pressure

1987 ◽  
Vol 65 (3) ◽  
pp. 266-285 ◽  
Author(s):  
Hirohisa Endo ◽  
Kozaburo Tamura ◽  
Makoto Yao
Keyword(s):  
Thermodynamic Properties ◽  
Electronic Properties ◽  
High Temperatures ◽  
Alkali Metals ◽  
High Pressures ◽  
Liquid Metals ◽  
Chain Structure ◽  
Metal Metal ◽  
Impurity Elements ◽  
Liquid Alkali Metals

Studies on the electronic and thermodynamic properties of liquid metals and semiconductors at high temperatures and high pressures are reviewed. A substantial decrease of volume for liquid alkali metals is brought about by the application of pressure. The interference function of liquid alkali metals with high pressure can be described by the hard-sphere model with a fixed packing fraction when one proceeds along the melting curve. For liquid Cs, the s–d resonance scattering plays an important role in the electron-transport properties at high pressures. In expanded liquid Hg, a metal–nonmetal transition occurs at a density near 9 g∙cm−3, and anomalous behaviour is found in the thermodynamic properties such as equation-of-state and density fluctuations. At low densities, substantial volume contraction and a large increase in conductivity are brought about by the addition of a small amount of Bi. At high temperatures and high pressures, liquid Se is transformed from a semiconducting state to a metallic state, accompanied by modification of chain structure. The measurements of sound velocity and optical properties reveal that the temperature and pressure at which the semiconductor–metal transition occurs are lowered by the addition of Te. It is suggested that the semiconductor–metal transition observed in liquid Se is induced by increasing fluctuations in the interchain distance and increasing interchain coupling. The electronic properties of liquid Se are substantially changed by the addition of impurity elements such as alkalis and halogens. Modification of chain structure is associated with the charge transfer between Se chains and impurity elements. To understand how the interchain coupling affects the electronic properties of liquid Se, the properties of the isolated Se chains confined in the pores of mordenite are studied. The pressure effects on the two-phase separation of liquid binary mixtures, such as metal–metal, metal–semiconductor, and metal – ionic salt mixtures, are also discussed.

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