Preparation, crystal structure, and superconductive characteristics of new oxynitrides (Nb{sub 1-x}M{sub x})(N{sub 1-y}O{sub y}) where M=Mg, Si, and x{approx}y

Journal Article · Mon Aug 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.06.003· OSTI ID:21580226

Ohashi, Yoshio; Motohashi, Teruki; Masubuchi, Yuji ^[1]; Moriga, Toshihiro; Murai, Keiichiro ^[2]; Kikkawa, Shinichi ^[1]

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1. Graduate School of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628 (Japan)
2. Graduate School of Advanced Technology and Science, University of Tokushima, 2-1 Minamijyousanjima-cho, Tokushima 770-8506 (Japan)

New niobium oxynitrides containing either magnesium or silicon were prepared at 1000 deg. C by ammonia nitridation of oxide precursors obtained via the citrate route. The products had rock-salt type crystal structures. Crystallinity was improved by annealing in 0.5 MPa N{sub 2} and the final compositions were (Nb{sub 0.95}Mg{sub 0.05})(N{sub 0.92}O{sub 0.08}) at 1500 deg. C and (Nb{sub 0.87}Si{sub 0.09{open_square}0.04})(N{sub 0.87}O{sub 0.13}) at 1200 deg. C. The magnesium and oxide ions partially co-substitute the niobium and nitride ions in the octahedral sites of the {delta}-NbN lattice, respectively. Silicon ions were also successfully doped together with oxide ions into the rock-salt type NbN lattice. The Si doped product exhibited relatively large displacement at the octahedral sites and was accompanied by a small amount of cation vacancies. Superconductivity was improved by annealing to obtain critical temperatures/volume fractions of T{sub c}=17.6 K/100% for Mg- and T{sub c}=16.2 K/95% for the Si-doped niobium oxynitrides. - Graphical Abstract: Doped silicon ions substituting Nb in (Nb{sub 0.87}Si{sub 0.09{open_square}0.04})(N{sub 0.87}O{sub 0.13}) introduced a large displacement at the 4a site mainly because of the accompanied vacancy. The silicon ions may also be slightly shifted from the regular octahedral 4a site (green) towards the interstitial tetrahedral site (red) statistically in the rock-salt type lattice. Highlights: > New superconducting niobium oxynitrides containing either magnesium or silicon were prepared. > Their annealed products had chemical compositions of (Nb{sub 0.95}Mg{sub 0.05})(N{sub 0.92}O{sub 0.08}) and (Nb{sub 0.87}Si{sub 0.09{open_square}0.04})(N{sub 0.87}O{sub 0.13}) in the rock-salt type structure. > Their superconductivities were T{sub c}/volume fraction=17.6 K/100% and 16.2 K/95%, respectively.

• OSTI ID: 21580226
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 8; Other Information: DOI: 10.1016/j.jssc.2011.06.003; PII: S0022-4596(11)00314-8; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANNEALING
CRITICAL TEMPERATURE
DOPED MATERIALS
INTERSTITIALS
MAGNESIUM
NEUTRON DIFFRACTION
NIOBIUM
NIOBIUM NITRIDES
OXIDES
SALT DEPOSITS
SILICON
SILICON IONS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
ALKALINE EARTH METALS
CHALCOGENIDES
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
GEOLOGIC DEPOSITS
HEAT TREATMENTS
IONS
MATERIALS
METALS
NIOBIUM COMPOUNDS
NITRIDES
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
POINT DEFECTS
REFRACTORY METAL COMPOUNDS
REFRACTORY METALS
SCATTERING
SEMIMETALS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSITION TEMPERATURE