Phase stability, elasticity, and theoretical strength of polonium from first principles

0349231 - ÚFM 2011 RIV US eng J - Journal Article
Legut, Dominik - Friák, Martin - Šob, Mojmír
Phase stability, elasticity, and theoretical strength of polonium from first principles.
Physical Review. B. Roč. 81, č. 21 (2010), 214118/1/-214118/19/. ISSN 1098-0121
R&D Projects: GA AV ČR IAA100100920; GA MŠMT(CZ) OC10008
Institutional research plan: CEZ:AV0Z20410507
Keywords : polonium * phase stability * elasticity * theoretical strength * ab initio calculations
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.772, year: 2010

We investigate the stability of Po in its ground-state simple cubic structure (alpha-Po) with respect to the trigonal spiral structure exhibited by Se and Te and to the displacive phase transformations into either tetragonal or trigonal phases. The origin of the phase stability of alpha-Po is elucidated and high elastic anisotropy of alpha-Po is explained as a consequence of its simple cubic structure. Finally, an uniaxial tensile test for loading along the [001] and [111] directions is simulated; the corresponding theoretical tensile strengths calculated within the LDA+SO approach amount to 4.2 GPa and 4.7 GPa, respectively, which are the lowest values predicted in an element so far. According to Pugh and Frantsevich criteria, alpha-Po is predicted to be ductile. Also a positive value of the Cauchy pressure confirms the metallic type of interatomic bonding.
Permanent Link: http://hdl.handle.net/11104/0189527