L 79 Lipatnikov, V. N. Formation of the incommensurate ordered phase in TaCy carbide [Текст] / V. N. Lipatnikov, A. A. Rempel // JETP Letters. - 2005. - Vol. 81, № 7. - С. 326-330. - Библиогр.: с. 330 (14 назв.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): КАРБИД ТАНТАЛА -- НЕСТЕХИОМЕТРИЯ Аннотация: Structural neutron diffraction studies indicate that only one ordered phase arises after the disorder–order transition in nonstoichiometric cubic tantalum carbide TaCy. This phase arises in the composition range y = 0.79–0.89 due to long-term annealing with a decrease in temperature from 1600 to 300 K. It is incommensurate in the [1–11]B1 direction, but it is close to commensurate M6C5 structures (C2/m and P31 space groups) in mutual arrangement of atoms and vacancies in nonmetallic (1–11)B1 planes. The disorder–order transition channel that is associated with the formation of the incommensurate superstructure in TaCy carbide includes two arms k(6)5~ 0.473b2 and k5(5) = – k5(6) of the {k5} star and arms of the {k4} and {k3} stars. The translation period of the incommensurate phase in the [1–11]B1 direction is 8.9–9.1 nm, which is larger than that in the commensurate phase M6C5 by a factor of about 18 Полный текст |