Abstract
Electron energy structure, positron spectrum and positron characteristics of α-Ti and α-TiH0.125 were calculated. Self-consistent calculations of the band structure were performed by the linear muffin-tin orbital method in the atomic sphere approximation. Modelling has been made on low content of hydrogen into α-Ti with expanded close-packed hexagonal cell inclusive 8 titanium atoms. Variation of sphere radiuses permitted to consider anisotropy and spherical symmetry of potential. Positron potential and positron wave function were calculated on a base of self-consistent electron density. Then positron probability of existence into TiHx lattice and lifetime were founded. Theoretical calculation indicated a satisfactory agreement of positron characteristics absolute values with the experimental data is achieved but the tendency of values with hydrogen defects increasing is not. The reason of divergence is discussed. On the basis of experimental data and theoretical calculations it was shown that different hydrogen atom states demonstrate the different influence in the lifetime spectra.
Highlights
Metals are the most important structural material
In this work we study influence of the atomic hydrogen on electron structure of titanium and its positron characteristics
Method of calculation Band structure of metal hydrides was calculated by the self-consistent linear muffin-tin orbital method in the atomic sphere approximation (LMTO-ASA) adjusted for overlap
Summary
Metals are the most important structural material. In many branch there is actual thread of hydrogen corrosion of metals. Modification of the physical and mechanical properties of metals and alloy materials by hydrogen is significant problem. Nondestructive and contactless methods, possibility to measure parameters of samples under different temperatures coupled with fast response to local change of electron density defines positron diagnostics as one of the unique method among traditional analysis of structure of matter. For metals and allows positron annihilation technique reveals the electron momentum distribution and Fermi level energy that largely determines their mechanical, electrical and magnetic properties [1]. Positron spectroscopy is sensitive to define structure, cause and concentration of spots and extended defects, to investigate the disrupt blanket on metals, alloys, semiconductors and ionic crystals [2]. In that case positron annihilation method is useful as for nature and concentration of impurities analysis as for study of electron structure modification because of any factors.
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