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Pugliese GM, Stramaglia F, Goto Y, Terashima K, Simonelli L, Fujiwara H, Puri A, Marini C, Hacisalihoglu MY, d'Acapito F, Yokoya T, Mizokawa T, Mizuguchi Y, Saini NL. Temperature dependent local atomic displacements in NaSn 2As 2 system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:425402. [PMID: 31226700 DOI: 10.1088/1361-648x/ab2bd4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
NaSn2As2 is mechanically exfoliable layered van der Waals (vdW) Zintl phase that is getting interesting due to its low thermal conductivity and recently observed superconductivity. Here, we have investigated the temperature dependent local structure of NaSn2As2 by a combined analysis of As K-edge and Sn K-edge extended x-ray absorption fine structure measurements. The system is intrinsically disordered with the interatomic distances largely consistent to those estimated by average structure measurements. The stretching force constants of different bond distances have been determined using temperature dependent mean square relative displacements. The Sn-As distance is the strongest bond in this system, having covalent nature, unlike the weaker interlayer distances which are characterized by vdW type bonding. Among them, As-Na distance is slightly weaker than Sn-Sn(i) below ∼200 K and tends to get stronger above this temperature. The anomalous behavior of As-Na bond suggests that the mechanical exfoliation in this system is likely to be temperature dependent. The anomaly in the interlayer atomic correlations may be due to a charge density wave-like instability around this temperature, indicated by earlier experiments. The local structure and disorder are discussed in relation to the physical properties of NaSn2As2.
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Izumikawa T, Takeshita S, Yamada T, Mizuguchi Y, Taniguchi N, Nakajima S, Hata T, Takahashi A. P1761Distal transradial approach for primary percutaneous coronary intervention for patients with acute myocardial infarction: a multicentre study. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz748.0514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
The distal transradial approach (dTRA) for coronary catheterisation is a newly introduced alternative to the conventional transradial approach. This technique is expected to decrease the incidence of haemorrhagic complications and improve patient comfort. However, limited data are available regarding the application of this technique in patients with acute myocardial infarction (AMI). This study investigated the feasibility and safety of the dTRA for primary percutaneous coronary intervention (PCI) in patients with AMI.
Methods
This study included patients with AMI who underwent primary PCI via the distal radial artery across 3 Japanese hospitals between January 2018 and January 2019. Patients' background, procedural characteristics, and clinical outcomes including the incidence of haemorrhagic complications were analysed.
Results
This study enrolled 95 consecutive patients with AMI, including 68 patients (71.6%) with ST-segment elevation myocardial infarction (STEMI), in whom distal radial artery puncture was attempted for primary PCI. The patients included 70 men (73.7%), and the mean age was 72.2±12.4 years. Among these patients, cannulation was successfully performed in 89 patients (93.7%). A 5-, 6-, or 7-French sheath (conventional or slender) was used in this study. Cannulation was performed using a forearm radial artery approach in patients in whom dTRA failed.
PCI was successfully performed in all patients. The meantime to achieve haemostasis was 6.3±5.3 hours, and no major bleeding complications occurred. Based on The Early Discharge After Transradial Stenting of Coronary Arteries trial haematoma scale, grade I, II, and III subcutaneous haemorrhages were observed in 16 (16.8%), 4 (4.2%), and 1 patient (1.1%), respectively. No patient developed a haematoma > grade IV.
In patients with STEMI, the mean door-to-balloon time was 39.4±31.9 min, and the mean puncture-to-balloon time was 19.7±14.2 min.
Conclusions
The distal radial approach is feasible and safefor primary PCI in selected patients with AMI.The application of the dTRA may serve as a less invasive strategy for the treatment of patients with AMI.
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Ito H, Miura A, Goto Y, Mizuguchi Y, Moriyoshi C, Kuroiwa Y, Azuma M, Liu J, Wen XD, Nishioka S, Maeda K, Masubuchi Y, Rosero-Navarro NC, Tadanaga K. An electronic structure governed by the displacement of the indium site in In-S 6 octahedra: LnOInS 2 (Ln = La, Ce, and Pr). Dalton Trans 2019; 48:12272-12278. [PMID: 31339138 DOI: 10.1039/c9dt01562k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
An extremely large displacement of the indium site in In-S6 octahedra in LnOInS2 (Ln = La, Ce, and Pr) was found in synchrotron X-ray diffraction. LaOInS2 with off-center indium in In-S6 octahedra exhibited a wider optical band gap than CeOInS2 and PrOInS2 with on-center indium. Therefore, the electronic structure of LnOInS2 is governed by the indium site with an extremely large displacement. All LnOInS2 produced H2 gas under visible light irradiation in the presence of sacrificial electron donors.
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Sudo K, Goto Y, Sogabe R, Hoshi K, Miura A, Moriyoshi C, Kuroiwa Y, Mizuguchi Y. Doping-Induced Polymorph and Carrier Polarity Changes in Thermoelectric Ag(Bi,Sb)Se 2 Solid Solution. Inorg Chem 2019; 58:7628-7633. [PMID: 31074617 DOI: 10.1021/acs.inorgchem.9b01038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Silver bismuth diselenide (AgBiSe2) is an n-type thermoelectric material that exhibits a complex structural phase transition from the hexagonal to cubic phase, while silver antimony diselenide (AgSbSe2) is a p-type thermoelectric material that crystallizes in the cubic phase at all temperatures. Here, we investigate the crystal structure and thermoelectric properties of Ag(Bi,Sb)Se2 solid solution, employing AgBi0.9Sb0.1Se2 and AgBi0.7Sb0.3Se2 as representative samples. The carrier polarity of AgBi0.9Sb0.1Se2 is converted from the n-type to p-type by Pb doping, accompanied by a polymorphic change to the cubic phase. It is difficult to obtain highly conductive p-type hexagonal AgBiSe2-based materials, although first-principles calculations predict high-performance thermoelectric properties for these systems. We also demonstrate that cubic AgBi0.7Sb0.3Se2 undergoes a polymorphic change to the hexagonal phase upon Nb doping. The present study show that polymorphic changes inevitably occurred upon Pb/Nb doping to optimize thermoelectric properties of Ag(Bi,Sb)Se2 solid solution.
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Paris E, Mizuguchi Y, Wakita T, Terashima K, Yokoya T, Mizokawa T, Saini NL. Suppression of structural instability in LaOBiS 2-x Se x by Se substitution. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:455703. [PMID: 30265246 DOI: 10.1088/1361-648x/aae501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Isovalent substitution of S by Se in LaOBiS2-x Se x has a substantial effect on its electronic structure and thermoelectric properties. To investigate the possible role of BiS2 structural instability, we have studied the local structure of LaOBiS2-x Se x ([Formula: see text]) using temperature dependent Bi L3-edge extended x-ray absorption fine structure measurements. The results reveal that the local structure of the two compounds is significantly different. The BiS2 sub-lattice is largely distorted in LaOBiS2 (x = 0.0), with two in-plane Bi-S1 distances separated by ∼0.4 Å instead LaOBiSSe (x = 1.0) showing much smaller local disorder with two in-plane Bi-Se distances in the plane being separated by ∼0.2 Å. Temperature dependent study shows that the two Bi-S1 distances are characterized by different bond strength in LaOBiS2 (x = 0.0) while it is similar for the Bi-Se distances in LaOBiSSe (x = 1.0). The out of plane Bi-S2 bond is harder in LaOBiSSe indicating that the structural instability of BiS2 layer has large effect on the out-of-plane atomic correlations. The results suggest that the local structure of LaOBiS2-x Se x is an important factor to describe differing electronic and thermal transport of the two compounds.
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Goto Y, Miura A, Moriyoshi C, Kuroiwa Y, Matsuda TD, Aoki Y, Mizuguchi Y. Na 1-xSn 2P 2 as a new member of van der Waals-type layered tin pnictide superconductors. Sci Rep 2018; 8:12852. [PMID: 30150765 PMCID: PMC6110830 DOI: 10.1038/s41598-018-31295-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/25/2018] [Indexed: 11/30/2022] Open
Abstract
Superconductors with a van der Waals (vdW) structure have attracted a considerable interest because of the possibility for truly two-dimensional (2D) superconducting systems. We recently reported NaSn2As2 as a novel vdW-type superconductor with transition temperature (Tc) of 1.3 K. Herein, we present the crystal structure and superconductivity of new material Na1−xSn2P2 with Tc = 2.0 K. Its crystal structure consists of two layers of a buckled honeycomb network of SnP, bound by the vdW forces and separated by Na ions, as similar to that of NaSn2As2. Amount of Na deficiency (x) was estimated to be 0.074(18) using synchrotron X-ray diffraction. Bulk nature of superconductivity was confirmed by the measurements of electrical resistivity, magnetic susceptibility, and specific heat. First-principles calculation using density functional theory shows that Na1−xSn2P2 and NaSn2As2 have comparable electronic structure, suggesting higher Tc of Na1−xSn2P2 resulted from increased density of states at the Fermi level due to Na deficiency. Because there are various structural analogues with tin-pnictide (SnPn) conducting layers, our results indicate that SnPn-based layered compounds can be categorized into a novel family of vdW-type superconductors, providing a new platform for studies on physics and chemistry of low-dimensional superconductors.
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Mizuguchi Y, Maruta M, Moriyama S, Yamashita N, Okada C, Nishimura A, Fujiwara Y, Tahakashi A. P5434Evaluation of the determinant factors on the capacity for self-care in patients with acute myocardial infarction. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy566.p5434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Miura A, Nagao M, Goto Y, Mizuguchi Y, Matsuda TD, Aoki Y, Moriyoshi C, Kuroiwa Y, Takano Y, Watauchi S, Tanaka I, Rosero-Navarro NC, Tadanaga K. Crystal Structure and Superconductivity of Tetragonal and Monoclinic Ce 1- xPr xOBiS 2. Inorg Chem 2018; 57:5364-5370. [PMID: 29676897 DOI: 10.1021/acs.inorgchem.8b00349] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ce1- xPr xOBiS2 powders and Ce0.5Pr0.5OBiS2 single crystals were synthesized and their structure and superconductive properties were examined by X-ray diffraction, X-ray absorption, electronic resistivity, and magnetization. While PrOBiS2 was found to be in a monoclinic phase with one-dimensional Bi-S zigzag chains showing no superconductive transition above 0.1 K, CeOBiS2 was in a tetragonal phase with two-dimensional Bi-S planes showing zero resistivity below 1.3 K. In the range x = 0.3-0.9 in Ce1- xPr xOBiS2, both monoclinic and tetragonal phases were formed together with zero resistivity up to a maximum temperature of 2.2 K. A Ce0.5Pr0.5OBiS2 single crystal, which showed both zero resistivity and a decrease in magnetization at ∼2.4 K, presented a tetragonal structure. Short Bi-S bonding in flat two-dimensional Bi-S planes and mixed Ce3+/Ce4+ were characteristic features of the Ce0.5Pr0.5OBiS2 single crystal, which presumably triggered its superconductivity.
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Goto Y, Nishida A, Nishiate H, Murata M, Lee CH, Miura A, Moriyoshi C, Kuroiwa Y, Mizuguchi Y. Effect of Te substitution on crystal structure and transport properties of AgBiSe2thermoelectric material. Dalton Trans 2018; 47:2575-2580. [DOI: 10.1039/c7dt04821a] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reduced lattice thermal conductivity of Te-substituted AgBiSe2was qualitatively described using the point defect scattering model.
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Hashimoto S, Takahashi A, Yamada T, Mizuguchi Y, Taniguchi N, Nakajima S, Hata T. P6075OCT guided excimer laser coronary angioplasty for in-stent restenosis. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx493.p6075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Paris E, Mizuguchi Y, Hacisalihoglu MY, Hiroi T, Joseph B, Aquilanti G, Miura O, Mizokawa T, Saini NL. Role of the local structure in superconductivity of LaO 0.5F 0.5BiS 2-x Se x system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:145603. [PMID: 28165329 DOI: 10.1088/1361-648x/aa5e97] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have studied the local structure of LaO0.5F0.5BiS2-x Se x by Bi L1-edge extended x-ray absorption fine structure (EXAFS). We find a significant effect of Se substitution on the local atomic correlations with a gradual elongation of average in-plane Bi-S bondlength. The associated mean square relative displacement, measuring average local distortions in the BiS2 plane, hardly shows any change for small Se substitution, but decreases significantly for [Formula: see text]. The Se substitution appears to suppress the local distortions within the BiS2 plane that may optimize in-plane orbital hybridization and hence the superconductivity. The results suggest that the local structure of the BiS2-layer is one of the key ingredients to control the physical properties of the BiS2-based dichalcogenides.
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Mizuguchi Y, Nishida A, Omachi A, Miura O. Thermoelectric properties of new Bi-chalcogenide layered compounds. ACTA ACUST UNITED AC 2016. [DOI: 10.1080/23311940.2016.1156281] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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38
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Goto Y, Seo J, Kumamoto K, Hisatomi T, Mizuguchi Y, Kamihara Y, Katayama M, Minegishi T, Domen K. Crystal Structure, Electronic Structure, and Photocatalytic Activity of Oxysulfides: La2Ta2ZrS2O8, La2Ta2TiS2O8, and La2Nb2TiS2O8. Inorg Chem 2016; 55:3674-9. [DOI: 10.1021/acs.inorgchem.6b00247] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Mizuguchi Y. Recent Advances in Layered Metal Chalcogenides as Superconductors and Thermoelectric Materials: Fe-Based and Bi-Based Chalcogenides. CHEM REC 2016; 16:633-51. [DOI: 10.1002/tcr.201500263] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Indexed: 11/09/2022]
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Miura A, Mizuguchi Y, Sugawara T, Wang Y, Takei T, Kumada N, Magome E, Moriyoshi C, Kuroiwa Y, Miura O, Tadanaga K. Structural Difference in Superconductive and Nonsuperconductive Bi-S Planes within Bi4O4Bi2S4 Blocks. Inorg Chem 2015; 54:10462-7. [PMID: 26479778 DOI: 10.1021/acs.inorgchem.5b01919] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The relationship between the structure and superconductivity of Bi4O4S3 powders synthesized by heating under ambient and high pressures was investigated using synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy (TEM) observation. The Bi4O4S3 powders synthesized under ambient pressure exhibited a strong superconductivity (diamagnetic) signal and zero resistivity below ∼4.5 K, while the Bi4O4S3 powder synthesized by the high-pressure method exhibited a low-intensity signal down to 2 K. Further annealing of the latter Bi4O4S3 powder under ambient pressure led to the development of a strong signal and zero resistivity. The crystal structures of all Bi4O4S3 phases consisted of Bi4O4Bi2S4 blocks including a Bi-S layer and anion(s) sandwiched between Bi4O4Bi2S4 blocks, but minor structural differences were detected. A comparison of the structures of the superconductive and nonsuperconductive Bi4O4S3 samples suggested that the superconductive Bi4O4S3 phases had slightly smaller lattice parameters. The average structures of the superconductive Bi4O4S3 phases were characterized by a slightly shorter and less bent Bi-S plane. Raman spectroscopy detected vibration of the S-O bonds, which can be attributed to sandwiched anion(s) such as SO4(2-). TEM observation showed stacking faults in the superconductive Bi4O4S3 phases, which indicated local fluctuation of the average structures. The observed superconductivity of Bi4O4S3 was discussed based on impurity phases, enhanced hybridization of the px and py orbitals of the Bi-S plane within Bi4O4Bi2S4 blocks, local fluctuation of the average structures, compositional deviation related to suspicious anion(s) sandwiched between Bi4O4Bi2S4 blocks, and the possibility of suppression of the charge-density-wave state by enriched carrier concentrations.
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Mizuguchi Y, Miura A, Kajitani J, Hiroi T, Miura O, Tadanaga K, Kumada N, Magome E, Moriyoshi C, Kuroiwa Y. In-plane chemical pressure essential for superconductivity in BiCh2-based (Ch: S, Se) layered structure. Sci Rep 2015; 5:14968. [PMID: 26447333 PMCID: PMC4597362 DOI: 10.1038/srep14968] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 09/14/2015] [Indexed: 11/08/2022] Open
Abstract
BiCh2-based compounds (Ch: S, Se) are a new series of layered superconductors, and the mechanisms for the emergence of superconductivity in these materials have not yet been elucidated. In this study, we investigate the relationship between crystal structure and superconducting properties of the BiCh2-based superconductor family, specifically, optimally doped Ce1-xNdxO0.5F0.5BiS2 and LaO0.5F0.5Bi(S1-ySey)2. We use powder synchrotron X-ray diffraction to determine the crystal structures. We show that the structure parameter essential for the emergence of bulk superconductivity in both systems is the in-plane chemical pressure, rather than Bi-Ch bond lengths or in-plane Ch-Bi-Ch bond angle. Furthermore, we show that the superconducting transition temperature for all REO0.5F0.5BiCh2 superconductors can be determined from the in-plane chemical pressure.
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Mizuguchi Y, Paris E, Sugimoto T, Iadecola A, Kajitani J, Miura O, Mizokawa T, Saini NL. The effect of RE substitution in layered REO(0.5)F(0.5)BiS2: chemical pressure, local disorder and superconductivity. Phys Chem Chem Phys 2015; 17:22090-6. [PMID: 26234627 DOI: 10.1039/c5cp03750f] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have studied the effect of RE substitution on the structure and the local atomic disorder in REO0.5F0.5BiS2 (RE = rare-earth) to understand their correlation with the bulk superconductivity in these materials. The mean RE size, affecting the chemical pressure, has been varied in two series namely Ce1-xNdxO0.5F0.5BiS2 and Nd1-ySmyO0.5F0.5BiS2. The lattice parameters evolve anomalously, showing an anisotropic shrinkage (elongation) of the c-axis (a-axis) to an isotropic expansion of the lattice with increasing mean RE size. The Bi L3-edge extended X-ray absorption fine structure (EXAFS) measurements are performed to investigate local displacements in the BiS2 lattice, revealing a large disorder and a sharp boundary between the Ce-containing and Sm-containing series with a distinct local structure. The results suggest that the bulk superconductivity in REO0.5F0.5BiS2 is correlated with anomalous atomic displacements in the Bi-S1 network, likely to be a combined effect of active Bi 6s electronic states and a possible Jahn-Teller-like instability of the Bi 6px/6py electrons.
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Paris E, Joseph B, Iadecola A, Sugimoto T, Olivi L, Demura S, Mizuguchi Y, Takano Y, Mizokawa T, Saini NL. Determination of local atomic displacements in CeO(1-x)F(x)BiS2 system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:435701. [PMID: 25299179 DOI: 10.1088/0953-8984/26/43/435701] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have used Bi and Ce L3-edges extended x-ray absorption fine structure measurements to study local structure of CeO(1-x)F(x)BiS2 system as a function of F-substitution. The local structure of both BiS2 active layer and CeO1-xFx spacer layer changes systematically. The in-plane Bi-S1 distance decreases (ΔRmax ∼ 0.08 Å) and the out-of-plane Bi-S2 distance increases (ΔRmax ∼ 0.12 Å) with increasing F-content. On the other hand, the Ce-O/F distance increases (ΔRmax ∼ 0.2 Å) with a concomitant decrease of the Ce-S2 distance (ΔRmax ∼ 0.15 Å). Interestingly, the Bi-S1 distance is characterized by a large disorder that increases with F-content. The results provide useful information on the local atomic displacements in CeO(1-x)F(x)BiS2, that should be important for the understanding of the coexistence of superconductivity and low temperature ferromagnetism in this system.
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Simonelli L, Saini NL, Mizuguchi Y, Takano Y, Mizokawa T, Baldi G, Monaco G. Electronic properties of FeSe(1-x)Te(x) probed by x-ray emission and absorption spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:415501. [PMID: 23006467 DOI: 10.1088/0953-8984/24/41/415501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The electronic structure of FeSe(1-x)Te(x) chalcogenide superconductors has been studied by x-ray emission (XES) and x-ray absorption (XAS) as a function of Te substitution. The Fe Kβ XES spectra reveal a relatively low spin state for Fe in FeSe(1-x)Te(x) superconductors, persisting in the whole range of Te substitution. The Fe K-edge high-resolution XAS shows systematic spectral changes due to the evolving hybridization between the Fe 3d (4p) and chalcogen p (d) orbitals. The resonant inelastic x-ray scattering (RIXS) spectra hardly show any feature except the one due to charge transfer from occupied to unoccupied bands, that changes substantially from FeSe to FeTe. The results provide important information on the electronic states and their evolution in the FeSe(1-x)Te(x) chalcogenides.
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Yokoya T, Yoshida R, Utsumi Y, Tsubota K, Okazaki H, Wakita T, Mizuguchi Y, Takano Y, Muro T, Kato Y, Kumigashira H, Oshima M, Harima H, Aiura Y, Sato H, Ino A, Namatame H, Taniguchi M, Hirai M, Muraoka Y. Te concentration dependent photoemission and inverse-photoemission study of FeSe 1-xTe x. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:054403. [PMID: 27877521 PMCID: PMC5099622 DOI: 10.1088/1468-6996/13/5/054403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 11/05/2012] [Indexed: 06/03/2023]
Abstract
We have characterized the electronic structure of FeSe1-x Te x for various x values using soft x-ray photoemission spectroscopy (SXPES), high-resolution photoemission spectroscopy (HRPES) and inverse photoemission spectroscopy (IPES). The SXPES valence band spectral shape shows that the 2 eV feature in FeSe, which was ascribed to the lower Hubbard band in previous theoretical studies, becomes less prominent with increasing x. HRPES exhibits systematic x dependence of the structure near the Fermi level (EF): its splitting near EF and filling of the pseudogap in FeSe. IPES shows two features, near EF and approximately 6 eV above EF; the former may be related to the Fe 3d states hybridized with chalcogenide p states, while the latter may consist of plane-wave-like and Se d components. In the incident electron energy dependence of IPES, the density of states near EF for FeSe and FeTe has the Fano lineshape characteristic of resonant behavior. These compounds exhibit different resonance profiles, which may reflect the differences in their electronic structures. By combining the PES and IPES data the on-site Coulomb energy was estimated at 3.5 eV for FeSe.
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Deguchi K, Takano Y, Mizuguchi Y. Physics and chemistry of layered chalcogenide superconductors. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:054303. [PMID: 27877516 PMCID: PMC5099617 DOI: 10.1088/1468-6996/13/5/054303] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 12/28/2012] [Accepted: 10/23/2012] [Indexed: 05/11/2023]
Abstract
Structural and physical properties of layered chalcogenide superconductors are summarized. In particular, we review the remarkable properties of the Fe-chalcogenide superconductors, FeSe and FeTe-based materials. Furthermore, we introduce the recently discovered BiS2-based layered superconductors and discuss their prospects.
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Takahashi H, Tomita T, Takahashi H, Mizuguchi Y, Takano Y, Nakano S, Matsubayashi K, Uwatoko Y. High-pressure studies on Tc and crystal structure of iron chalcogenide superconductors. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:054401. [PMID: 27877519 PMCID: PMC5099620 DOI: 10.1088/1468-6996/13/5/054401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 10/01/2012] [Indexed: 06/06/2023]
Abstract
The superconducting transition temperature, Tc, in iron-based solids can be enhanced by applied pressure: Tc increases from 8 to 37 K for the 11-type FeSe when the pressure is raised from 0 to 4 GPa. High-pressure studies can elucidate the mechanism of superconductivity in such novel materials. In this paper, we present a high-pressure study of Fe(Se1-x Te x ) and Fe(Se1-x S x ). In the case of Fe(Se1-x Te x ), the maximum Tc under high pressure did not exceed the Tc of FeSe, which can be attributed to the structural transition to the monoclinic phase. For Fe(Se1-x S x ) (0 < x < 0.3), Tc exhibited a significant increase with pressure; however, the maximum Tc under high pressure did not exceed the Tc of FeSe. This may be due to the disorder induced by substituting S for Se, which is similar to the pressure effect on Tc for the 1111-type superconductor Ca(Fe1-x Co x )AsF. The Tc of Fe(Se1-x S x ) showed a complex behavior below 1 GPa, first decreasing and then increasing with increasing pressure. From high-pressure x-ray diffraction measurements, the Tc (P) curve was correlated with the local structural parameter.
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Iadecola A, Joseph B, Simonelli L, Puri A, Mizuguchi Y, Takeya H, Takano Y, Saini NL. Large local disorder in superconducting K(0.8)Fe(1.6)Se2 studied by extended x-ray absorption fine structure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:115701. [PMID: 22353735 DOI: 10.1088/0953-8984/24/11/115701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have measured the local structure of superconducting K(0.8)Fe(1.6)Se(2) chalcogenide (T(c) = 31.8 K) by temperature dependent polarized extended x-ray absorption fine structure (EXAFS) at the Fe and Se K-edges. We find that the system is characterized by a large local disorder. The Fe-Se and Fe-Fe distances are found to be shorter than the distances measured by diffraction, while the corresponding mean square relative displacements reveal large Fe-site disorder and relatively large c-axis disorder. The local force constant for the Fe-Se bondlength (k ~ 5.8 eV Å(-2)) is similar to the one found in the binary FeSe superconductor, however, the Fe-Fe bondlength appears to be flexible (k ~ 2.1 eV Å(-2)) in comparison to the binary FeSe (k ~ 3.5 eV Å(-2)), an indication of partly relaxed Fe-Fe networks in K(0.8)Fe(1.6)Se(2). The results suggest a glassy nature for the title system, with the superconductivity being similar to that in the granular materials.
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Iadecola A, Joseph B, Puri A, Simonelli L, Mizuguchi Y, Testemale D, Proux O, Hazemann JL, Takano Y, Saini NL. Random alloy-like local structure of Fe(Se, S)(1-x)Te(x) superconductors revealed by extended x-ray absorption fine structure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:425701. [PMID: 21983016 DOI: 10.1088/0953-8984/23/42/425701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The local structure of Fe(Se, S)(1-x)Te(x) ternary (11-type) chalcogenides has been studied by temperature dependent Fe K-edge extended x-ray absorption fine structure measurements. We find that the Fe-Se and Fe-Te distances in ternary FeSe(1-x)Te(x) are closer to the respective distances in the binary systems, revealing significant divergence of the local structure from the average one. The mean square relative displacements show a systematic change with Te content, consistent with bond relaxation in the inhomogeneous ternary phases. Also, the Fe-Te and Fe-S distances in the FeS(0.2)Te(0.8) ternary system are found to be different in the crystallographically homogeneous structure. The observed features are characteristic of ternary random alloys, suggesting that a proper consideration should be given to the atomic distribution for describing the complex electronic structure of these multi-band Fe-based chalcogenides.
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