Effect of short-range ordering on the electrical conductivity and superconducting properties of Nb{sub 6}C{sub 5} single crystals
- Institute of Structural Macrokinetics, Chernogolovka (Russian Federation)
Niobium carbide, NbC{sub x}, belongs to the family of so called interstital phases. Metal atoms form a face-centered cubic lattice, whose octahedral interstices are occupied by carbon atoms. The fraction (1 - x) of interstices remain vacant, and this determines the nonstoichiometry of these phases: most of them are characterized by a wide homogeneity range, 0.70<0.99. The metal sublattice can be considered as a rigid framework, stable up to the melting point of carbide (T{sub m}{approx_equal} 3308 - 3886 K). In contrast, the metalloid atoms exhibit high mobility at relatively low temperatures. For compositions close to Nb{sub 6}C{sub 5} (0.81 < x < 0.88), the order-disorder (O-D) phase transition is observed at T{sub O-D}{approx_equal} 1300 K. The presence of vacancies in the carbon sublattice considerably affects the physical properties of carbides, which depend not only on total vacancy concentration but also on their distribution, i.e., on the degree of ordering (both short-range and long-range order) in the metalloid sublattice. The purpose of this work is to study the effects of such ordering on the superconducting properties of Nb{sub 6}C{sub 5} single crystals.
- OSTI ID:
- 161911
- Journal Information:
- Inorganic Materials, Vol. 31, Issue 7; Other Information: PBD: Jul 1995; TN: Translated from Neorganicheskie Materialy; 31: No. 7, 930-933(1995)
- Country of Publication:
- United States
- Language:
- English
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