S 53 Shein, I. R. Influence of lattice vacancies on the structural, electronic, and cohesive properties of niobium and molybdenum borides from first-principles calculations [Text] / I. R. Shein, A. L. Ivanovskii // Physical Review B: Condensed Matter and Materials Physics. - 2006. - Vol. 73, № 14. - P144108/1-144108/9. - Библиогр. : с. 144108/8 (55 назв.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): БОРИД МОЛИБДЕНА -- БОРИД НИОБИЯ -- ПЕРВОПРИНЦИПНЫЕ РАСЧЕТЫ Аннотация: The influence of lattice vacancies on the structural, cohesive, and electronic properties of Nb and Mo borides were examined by means of the full-potential linearized augmented plane wave method and the generalized gradient approximation. The structural parameters, densities of states (DOS), charge distribution, heats of formations, and vacancy formation energies for metal-deficient hexagonal Nb1−xB2, Mo1−xB2 as well as for boron-deficient rhombohedral Mo2B5−y were obtained and compared with those for complete hexagonal NbB2, MoB2 and rhombohedral Mo2B5. We show that the presence of metal vacancies in hexagonal phases leads to (i) the decreasing of in-plane parameter a but increasing the interplane cell parameter c; (ii) well pronounced changes of near-Fermi DOS and the appearance of the novel vacancy states; and (iii) a substantial decrease in the stability of borides. On the contrary, in the case of Mo2B5 the appearance of the boron vacancies leads to enhancing of stability of a rhombohedral phase Полный текст |