A combined experimental and computational study of the Ca5Si3 phase is presented. Its' electronic structure and lattice stability are investigated by first principles methods: four different crystal lattices have been investigated by means of density functional theory (DFT) calculations and pseudopotentials within the generalized-gradient approximation using the VASP code. The Ca5Si3 phase is predicted to undergo an high pressure transition: the lattice transition tI32(Cr5B3-type)!tI32(W5Si3-type) has been predicted by DFT to occur at 14.9 GPa. The electronic and band structure of the tI32 Cr5B3-type lattice is calculated and discussed. The Ca5Si3 phase ground state structure is predicted to be a metal with a peaked density of states below the Fermi energy and a sharp minimum right above it. Experimentally the low temperature resistivity and heat capacity of the Ca5Si3 phase have been measured between 2 and 300 K and discussed in view of our computational predictions and available literature. The Ca5Si3 tI32(Cr5B3-type) standard pressure polymorph exhibits a metallic temperature dependence of the electric conductivity in agreement with the DFT predictions.

Electronic, electrical and thermodynamic properties of Ca5Si3 by first principles calculations and low temperature experimental techniques

BRUTTI, SERGIO;
2009

Abstract

A combined experimental and computational study of the Ca5Si3 phase is presented. Its' electronic structure and lattice stability are investigated by first principles methods: four different crystal lattices have been investigated by means of density functional theory (DFT) calculations and pseudopotentials within the generalized-gradient approximation using the VASP code. The Ca5Si3 phase is predicted to undergo an high pressure transition: the lattice transition tI32(Cr5B3-type)!tI32(W5Si3-type) has been predicted by DFT to occur at 14.9 GPa. The electronic and band structure of the tI32 Cr5B3-type lattice is calculated and discussed. The Ca5Si3 phase ground state structure is predicted to be a metal with a peaked density of states below the Fermi energy and a sharp minimum right above it. Experimentally the low temperature resistivity and heat capacity of the Ca5Si3 phase have been measured between 2 and 300 K and discussed in view of our computational predictions and available literature. The Ca5Si3 tI32(Cr5B3-type) standard pressure polymorph exhibits a metallic temperature dependence of the electric conductivity in agreement with the DFT predictions.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11563/27032
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