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We have investigated the influence of Ca ions substitution on the structural and superconducting properties of (Nd1-xCax)(Ba1.6La0.4)Cu3Oz system. Magnetization, X-ray diffraction and neutron diffraction studies have been carried out on a…

Superconductivity · Physics 2010-05-14 Amish G. Joshi , R. G. Kulkarni , W. B. Yelon , Ram Prasad , M. R. Gonal

We have compared by $^{23}$Na NMR and magnetic susceptibility the magnetic properties of oriented powder samples of Na$_{x}$CoO$_{2}$ compounds. The NMR spectra are found identical for various samples with nominal $0.50\leq x\leq 0.70,$…

Strongly Correlated Electrons · Physics 2007-05-23 I. R. Mukhamedchine , H. Alloul , G. Collin , N. Blanchard

Structural investigations by means of transmission electron microscopy (TEM) on KFexSe2 with 1.5 \leq x \leq 1.8 have revealed a rich variety of microstructure phenomena, the KFe1.5Se2 crystal often shows a superstructure modulation along…

Superconductivity · Physics 2013-05-29 Z. Wang , Y. J. Song , H. L. Shi , Z. W. Wang , Z. Chen , H. F. Tian , G. F. Chen , J. G. Guo , H. X. Yang , J. Q. Li

We report the synthesis and superconducting properties of a metastable form of the known superconductor NaxCoO2*yH2O (x ~ 1/3, y ~ 4x). Instead of using the conventional bromine-acetonitrile mixture for sodium deintercalation, we use an…

Materials Science · Physics 2009-11-11 P. W. Barnes , M. Avdeev , J. D. Jorgensen , D. G. Hinks , H. Claus , S. Short

Based on first-principles calculations we show that the oxidation of ultrathin films of Ca$_2$N electrides, electrenes, drives a hexagonal$\rightarrow$tetragonal structural transition. The ground state configuration of the oxidized…

Materials Science · Physics 2020-05-06 Pedro H. Souza , José E. Padilha , Roberto H. Miwa

Precise structural information on the Mg1-xAlxB2 superconductors in the vicinity of x 0.5 is derived from high-resolution synchrotron X-ray powder diffraction measurements. We find that a hexagonal superstructure, accompanied by doubling of…

Materials Science · Physics 2009-11-07 S. Margadonna , K. Prassides , I. Arvanitidis , M. Pissas , G. Papavassiliou , A. N. Fitch

Transmission electron microscopy observations reveal the presence of complex superstructures and remarkable phase separation in association with Na-ordering phenomenon in y-Na0.5CoO2. Resistivity and magnetization measurements indicate that…

Strongly Correlated Electrons · Physics 2007-05-23 H. X. Yang , Y. G. Shi , C. J. Nie , D. Wu , L. X. Yang , C. Dong , H. C. Yu , H. R. Zhang , C. Q. Jin , J. Q. Li

The incidence of topology on the band structure and physical properties of layered compounds has been extensively studied in semimetals. How those evolve in presence of electronic correlations has been less investigated so far. In the…

Strongly Correlated Electrons · Physics 2020-04-20 I. F. Gilmutdinov , I. R. Mukhamedshin , H. Alloul

The interplay between unconventional superconductivity and the ordering of charge/spin density wave is one of the most vital issues in both condensed matter physics and material science. The Ti-based compound BaTi_2As_2O, which can be seen…

Recent studies exposed many remarkable properties of layered cobaltates NaxCoO2. Surprisingly, many-body effects have been found to increase at sodium-rich compositions of NaxCoO2 where one expects a simple, nearly free motion of the dilute…

Strongly Correlated Electrons · Physics 2015-05-13 J. Chaloupka , G. Khaliullin

A new layered iron-oxychalcogenide Na2Fe2OSe2 has been synthesized and structurally characterized by powder X-ray diffraction. The structure is formed by alternate stacking of the newly discovered [Fe2OSe2] blocks and double layers of Na.…

Strongly Correlated Electrons · Physics 2013-05-29 J. B. He , D. M. Wang , H. L. Shi , H. X. Yang , J. Q. Li , G. F. Chen

Numerous different crystal structures of Ta2O5 are reported in literature. Although experimentally and computationally obtained lattice parameters and mechanical properties are in excellent agreement there is a pronounced deviation when it…

We study the optical properties of the layered rhodium oxide K0.49RhO2, which is isostructural to the thermoelectric material NaxCoO2. The optical conductivity shows broad interband transition peaks as well as a low-energy Drude-like…

Strongly Correlated Electrons · Physics 2011-08-09 R. Okazaki , Y. Nishina , Y. Yasui , S. Shibasaki , I. Terasaki

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na0.31(3)CoO2o1.25(2)D2O and its anhydrous…

Superconductivity · Physics 2009-11-10 J. D. Jorgensen , M. Avdeev , D. G. Hinks , J. C. Burley , S. Short

We report on the observation of rich variety of crystallographic phase formation in RexMo1-xS2 alloy for x < 0.5. For x < 0.23, no low dimensional super-structural modulation is observed and inter-cation hybridization remains discrete…

Materials Science · Physics 2020-01-08 H. Sharona , B. Vishal , U. Bhat , A. Paul , A. Mukherjee , S. C. Sarma , S. C. Peter , R. Datta

We present our NMR studies of double-layer hydrated cobalt oxides NaxCoO2-yH2O (x ~ 0.35, y ~ 1.3) with various Tc = 0 - 4.8 K and magnetic transition temperatures. High-resolution $^{1}$H NMR spectrum served as an evidence for the…

Superconductivity · Physics 2015-05-13 Y. Itoh , H. Ohta , C. Michioka , M. Kato , K. Yoshimura

The structural and magnetic properties of the hexagonal four-layer form of SrMnO$_3$ have been investigated by combining magnetization measurements, electron diffraction and high-resolution synchrotron X-ray and neutron powder diffraction.…

Strongly Correlated Electrons · Physics 2007-05-23 A. Daoud-Aladine , C. Martin , L. C. Chapon , M. Hervieu , K. S. Knight , M. Brunelli , P. G. Radaelli

Layered Co oxide NaxCoO2.yH2O with a superconducting transition temperature Tc =4.5 K has been studied by 59Co NQR. The nuclear spin relaxation rate 1/59T1 is nearly proportional to temperature T in the normal state. In the superconducting…

Superconductivity · Physics 2009-11-10 Yoshiaki Kobayashi , Mai Yokoi , Masatoshi Sato

At ambient temperatures, CeRuSn exhibits an extraordinary structure with a coexistence of two types of Ce ions in a metallic environment, namely trivalent Ce3+ and intermediate valent Ce(4-x)+. Charge ordering produces a doubling of the…

Strongly Correlated Electrons · Physics 2012-02-24 R. Feyerherm , E. Dudzik , S. Valencia , J. A. Mydosh , Y. -K. Huang , W. Hermes , R. Pöttgen

Although crystalline solids are characterized by their periodic structures, some are only periodic on average and deviate on a local scale. Distinct local orderings can exist with identical periodic structures making their differences…

Materials Science · Physics 2021-07-02 Nikolaj Roth , Jonas Beyer , Karl F. F. Fischer , Kaiyang Xia , Tiejun Zhu , Bo Brummerstedt Iversen