Crystal chemistry and structural design of iron-based superconductors

Jiang, Hao; Sun, Yun-Lei; Xu, Zhu-An; Cao, Guanghan

doi:10.1088/1674-1056/22/8/087410

Cited by 59 publications

(79 citation statements)

References 123 publications

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“…[3][4][5] Remarkably, dozens of Fe-based superconductors (FeSCs) were discovered, which can be classified into several crystallographic types. 5 All these FeSCs necessarily contain anti-fluorite-like Fe 2 X 2 (X denotes a pnictogen or a chalcogen element) layers.…”

Section: Introductionmentioning

confidence: 99%

A New ZrCuSiAs-Type Superconductor: ThFeAsN

Wang

Mei

et al. 2016

J. Am. Chem. Soc.

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ABSTRACT:We report the first nitrogen-containing iron-pnictide superconductor ThFeAsN, which is synthesized by a solid-state reaction in an evacuated container. The compound crystallizes in a ZrCuSiAs-type structure with the space group P4/nmm and lattice parameters a=4.0367(1) Å and c=8.5262(2) Å at 300 K. The electrical resistivity and dc magnetic susceptibility measurements indicate superconductivity at 30 K for the nominally undoped ThFeAsN.The discovery of high-temperature superconductivity in iron based compounds 1,2 triggered enormous researches, and a lot of progresses in material and mechanism aspects have been achieved. [3][4][5] Remarkably, dozens of Fe-based superconductors (FeSCs) were discovered, which can be classified into several crystallographic types. 5 All these FeSCs necessarily contain anti-fluorite-like Fe 2 X 2 (X denotes a pnictogen or a chalcogen element) layers. Another important feature for FeSCs is that the high-temperature superconductivity is mostly induced by suppressing the spin-density wave (SDW) order in a parent compound, typically through chemical dopings or applying pressures.The (Ref. 13 ). Note that the valence of the A-site cations is either 3+ or 2+. We previously succeeded in doping a tetravalent Th 4+ ion into the A site, 9,14 which produces superconductivity with a T c up to 56 K. 9 To expand the FeSC spectrum and, possibly to further increase the T c , it is of great interest to explore a possible A 4+ Z 3 combination for the fluorite-like spacer layer in the 1111 system. and AeFX (X=Cl, Br, I). 18 This structural relation suggests that iron pnictide containing [Th 2 N 2 ] 2+ layers could be thermodynamically stable. In this Communication, we report our successful synthesis of the target material, ThFeAsN, using solid-state reactions at high temperatures. The as-prepared sample shows bulk superconductivity at 30 K without any deliberate oxygen doping.In general, nitrides are synthetically challenging, presumably because of the potential oxygen incorporation. Therefore, the precursors of Th 3 N 4 , Th metal and FeAs are carefully synthesized avoiding oxygen contamination as far as possible. First, thorium powders were produced by the reduction of thorium oxide with metal calcium. 19 The yielded thorium metal powder was consolidated into a button with silver luster using an arc furnace. After that, the button was scraped in a glove box filled with argon (99.9999%) to get clean thorium powder. Then, nearly monophasic Th 3 N 4 (possibly with trace ThN) was synthesized by the reaction with 20% excess high-purity nitrogen gas (99.999%) at 1000 C for 24 hours in an evacuated quartz ampoule. FeAs was prepared by heating the mixture of iron (99.99%) and arsenic (99.999%) powders in an evacuated quartz ampoule at 700 C for 48 hours. All the precursors had been checked by X-ray diffractions (XRD) before using [figures S1 and S2 in the Supporting Information (SI)]. Similarly, the solid-state reaction of the stoichiometric mixture of Th 3 N 4 , Th and FeAs was also carried o...

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Section: Introductionmentioning

confidence: 99%

A New ZrCuSiAs-Type Superconductor: ThFeAsN

Wang

Mei

et al. 2016

J. Am. Chem. Soc.

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“…Particularly, the two 2D networks structurally match in symmetry and size, and therefore it is possible to form a hybrid structure with both CuO 2 planes and Fe 2 X 2 layers [5][6][7] . However, previous efforts to synthesize the target materials were unsuccessful 8 , which is possibly because Cu (Fe) more easily bonds with X (O) according to the "Hard and Soft Acids and Bases" concept 7,9 .…”

Section: Introductionmentioning

confidence: 99%

“…However, previous efforts to synthesize the target materials were unsuccessful 8 , which is possibly because Cu (Fe) more easily bonds with X (O) according to the "Hard and Soft Acids and Bases" concept 7,9 . In fact, a similar compound, Sr 2 Mn 3 As 2 O 2 (2322), which contains alternating MnO 2 sheets and Mn 2 As 2 layers, was reported earlier in 1979 10 .…”

Section: Introductionmentioning

confidence: 99%

“…Later in 1990s, a series of 2322-type materials were synthesized and characterized [11][12][13][14][15][16][17][18] , presumably due to the structural similarity with cuprate superconductors. Since the birth of high-temperature iron-based superconductors in 2008, there has been a renewed interest on studying the related systems 7,8,[19][20][21][22][23] . Among them, the Crcontaining iron arsenide Sr 2 CrO 2 Fe 2 As 2 23 seems to be very close to superconductivity, because it comprises of the superconductively active Fe 2 As 2 layers and, a self doping may be realized through charge transfer between the distinct layers, like the cases in Sr 2 VFeAsO 3 24 and Ba 2 Ti 2 Fe 2 As 4 O 25 .…”

Section: Introductionmentioning

confidence: 99%

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Physical properties and electronic structure ofSr2Cr3As2O2containingCrO2
Jiang
¹
,
Bao
²
,
Zhai
³

et al. 2015
Phys. Rev. B
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We report the physical properties and electronic structure calculations of a layered chromium oxypnictide, Sr2Cr3As2O2, which crystallizes in a Sr2Mn3As2O2-type structure containing both CrO2 planes and Cr2As2 layers. The newly synthesized material exhibits a metallic conduction with a dominant electron-magnon scattering. Magnetic and specific-heat measurements indicate at least two intrinsic magnetic transitions below room temperature. One is an antiferromagnetic transition at 291 K, probably associated with a spin ordering in the Cr2As2 layers. Another transition is broad, occurring at around 38 K, and possibly due to a short-range spin order in the CrO2 planes. Our first-principles calculations indicate predominant two-dimensional antiferromagnetic exchange couplings, and suggest a KG-type (i.e. K2NiF4 type for CrO2 planes and G type for Cr2As2 layers) magnetic structure, with reduced moments for both Cr sublattices. The corresponding electronic states near the Fermi energy are mostly contributed from Cr-3d orbitals which weakly (modestly) hybridize with the O-2p (As-4p) orbitals in the CrO2 (Cr2As2) layers. The bare bandstructure density of states at the Fermi level is only ∼1/4 of the experimental value derived from the lowtemperature specific-heat data, consistent with the remarkable electron-magnon coupling. The title compound is argued to be a possible candidate to host superconductivity.

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“…13,20 As is known, most FeSCs are realized through chemical doping in so-called parent compounds. 3, 5 Here the occurrence of superconductivity in KCa 2 Fe 4 As 4 F 2 is also due to hole doping, yet by the material itself, as the constituents of KCa 2 Fe 4 As 4 F 2 , namely, CaFeAsF 11 and KFe 2 As 2 , 17 are a parent compound and a 3.8 K superconductor, respectively. The structural hybridization changes the Fe valence to 2.25+, as mentioned above.…”

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confidence: 99%

Superconductivity in KCa₂Fe₄As₄F₂ with Separate Double Fe₂As₂ Layers

et al. 2016

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We report the synthesis, crystal structure, and physical properties of a quinary iron arsenide fluoride, KCa2Fe4As4F2. The new compound crystallizes in a body-centered tetragonal lattice (space group I4/mmm, a = 3.8684(2) Å, c = 31.007(1) Å, Z = 2) that contains double Fe2As2 conducting layers separated by insulating Ca2F2 layers. Our measurements of electrical resistivity, direct-current magnetic susceptibility, and heat capacity demonstrate bulk superconductivity at 33 K in KCa2Fe4As4F2.

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Crystal chemistry and structural design of iron-based superconductors

Cited by 59 publications

References 123 publications

A New ZrCuSiAs-Type Superconductor: ThFeAsN

A New ZrCuSiAs-Type Superconductor: ThFeAsN

Physical properties and electronic structure ofSr2Cr3As2O2containingCrO2
Jiang
¹
,
Bao
²
,
Zhai
³

et al. 2015
Phys. Rev. B
Self Cite
30
7
53
0
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Superconductivity in KCa₂Fe₄As₄F₂ with Separate Double Fe₂As₂ Layers

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Crystal chemistry and structural design of iron-based superconductors

Cited by 59 publications

References 123 publications

A New ZrCuSiAs-Type Superconductor: ThFeAsN

A New ZrCuSiAs-Type Superconductor: ThFeAsN

Physical properties and electronic structure ofSr2Cr3As2O2containingCrO2Jiang1, Bao2, Zhai3 et al. 2015Phys. Rev. BSelf Cite307530View full textAdd to dashboardCite

Superconductivity in KCa2Fe4As4F2 with Separate Double Fe2As2 Layers

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Physical properties and electronic structure ofSr2Cr3As2O2containingCrO2
Jiang
¹
,
Bao
²
,
Zhai
³

et al. 2015
Phys. Rev. B
Self Cite
30
7
53
0
View full text Add to dashboard Cite

Superconductivity in KCa₂Fe₄As₄F₂ with Separate Double Fe₂As₂ Layers