73 research outputs found
New ternary ThCr2Si2-type iron-selenide superconducting materials: synthesis, properties and simulations
Very recently (November, 2010, PRB, 82, 180520R), the first ThCr2Si2-type
ternary superconductor K0.8Fe2Se2 with enhanced TC ~ 31 K has been discovered.
This finding has stimulated much activity in search for related materials and
triggered intense studies of their properties. Indeed, very soon
superconductivity (TC ~ 28-32 K) was also found in the series of related
ternary systems (so-called 122 phases) such as CsxFe2-ySe2, RbxFe2-ySe2,
(TlK)xFeySe2, (TlRb)xFeySe2 etc., which formed a new group of superconducting
iron-based materials without toxic As. In this paper the recent progress in
synthesis of 122-like iron-selenide systems and in experimental research of
their properties is reviewed. Available theoretical data on electronic,
magnetic, and elastic properties of this newest group of superconducting
materials are also discussed.Comment: 44 pages, 27 figure
BN domains included into carbon nanotubes: role of interface
We present a density functional theory study on the shape and arrangement of
small BN domains embedded into single-walled carbon nanotubes. We show a strong
tendency for the BN hexagons formation at the simultaneous inclusion of B and N
atoms within the walls of carbon nanotubes. The work emphasizes the importance
of a correct description of the BN-C frontier. We suggest that BN-C interface
will be formed preferentially with the participation of N-C bonds. Thus, we
propose a new way of stabilizing the small BN inclusions through the formation
of nitrogen terminated borders. The comparison between the obtained results and
the available experimental data on formation of BN plackets within the single
walled carbon nanotubes is presented. The mirror situation of inclusion of
carbon plackets within single walled BN nanotubes is considered within the
proposed formalism. Finally, we show that the inclusion of small BN plackets
inside the CNTs strongly affects the electronic character of the initial
systems, opening a band gap. The nitrogen excess in the BN plackets introduces
donor states in the band gap and it might thus result in a promising way for
n-doping single walled carbon nanotubes
Structural, Magnetic and Electronic Properties of the Iron-Chalcogenide AFeSe (A=K, Cs, Rb, Tl and etc.) Superconductors
The latest discovery of a new iron-chalcogenide superconductor
AFeSe(A=K, Cs, Rb, Tl and etc.) has attracted much attention
due to a number of its unique characteristics, such as the possible insulating
state of the parent compound, the existence of Fe-vacancy and its ordering, a
new form of magnetic structure and its interplay with superconductivity, and
the peculiar electronic structures that are distinct from other Fe-based
superconductors. In this paper, we present a brief review on the structural,
magnetic and electronic properties of this new superconductor, with an emphasis
on the electronic structure and superconducting gap. Issues and future
perspectives are discussed at the end of the paper.Comment: 45 pages, 19 figure
Modeling of the atomic structure and thermal stability of titanium monoxide nanocrystals
Effect of substrate temperature on structural and materials properties of zirconium nitride films on D9 steel substrates
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