An Extension of Pnictide Oxide Chemistry – Salt Flux Synthesis and Structure of La5Cu4As4O4Cl2

Eul, Matthias; Johrendt, Dirk; Pöttgena, Rainer

doi:10.1515/znb-2009-11-1215

Cited by 17 publications

(7 citation statements)

References 22 publications

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“…The insulating nature of the compound leads to a Seebeck coefficient of +610 (10) μV/K at 300 K (Figure 4b), which is larger than the room temperature value of pristine BiOCuSe. 22 Both Seebeck and resistivity were measured multiple times with consistent values.…”

Section: ■ Associated Contentmentioning

confidence: 91%

“…There are only a few examples of layered materials with three anions, of which some are also isoelectronic and isostructural to materials with two anions, such as (SrF) 2 Ti 2 OSb 2 and (SrF) 2 Fe 2 OSe 2 , which have structural analogues in (SmO) 2 Ti 2 OSb 2 and (LaO) 2 Fe 2 OSe 2 . Recently, the complex multiple anion material La 5 O 4 Cu 4 As 4 Cl 2 was reported, with LaO, Cl, CuAs, and La layers, along with a P-containing analogue . However, no general design principles for these types of multiple anion materials have been proposed, which would be of interest for the design and tuning of new materials based on anion substitution.…”

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confidence: 99%

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Bi₄O₄Cu_1.7Se_2.7Cl_0.3: Intergrowth of BiOCuSe and Bi₂O₂Se Stabilized by the Addition of a Third Anion

et al. 2017

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Layered two-anion compounds are of interest for their diverse electronic properties. The modular nature of their layered structures offers opportunities for the construction of complex stackings used to introduce or tune functionality, but the accessible layer combinations are limited by the crystal chemistries of the available anions. We present a layered three-anion material, BiOCuSeCl, which adopts a new structure type composed of alternately stacked BiOCuSe and BiOSe-like units. This structure is accessed by inclusion of three chemically distinct anions, which are accommodated by aliovalently substituted BiOSeCl blocks coupled to Cu-deficient BiOCuSe blocks, producing a formal charge modulation along the stacking direction. The hypothetical parent phase BiOCuSe is unstable with respect to its charge-neutral stoichiometric building blocks. The complex layer stacking confers excellent thermal properties upon BiOCuSeCl: a room-temperature thermal conductivity (κ) of 0.4(1) W/mK was measured on a pellet with preferred crystallite orientation along the stacking axis, with perpendicular measurement indicating it is also highly anisotropic. This κ value lies in the ultralow regime and is smaller than those of both BiOCuSe and BiOSe. BiOCuSeCl behaves like a charge-balanced semiconductor with a narrow band gap. The chemical diversity offered by the additional anion allows the integration of two common structural units in a single phase by the simultaneous and coupled creation of charge-balancing defects in each of the units.

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Section: ■ Associated Contentmentioning

confidence: 91%

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confidence: 99%

Bi₄O₄Cu_1.7Se_2.7Cl_0.3: Intergrowth of BiOCuSe and Bi₂O₂Se Stabilized by the Addition of a Third Anion

et al. 2017

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“…cited therein A peculiar case is the structure of La 5 Cu 4 As 4 O 4 Cl 2 containing incorporated chloride from a reactive salt flux. 18 Furthermore, the typical signs of charge density wave formation have also been observed in the titanium based phases BaTi 2 Sb 2 O and Ba 1-x K x Ti 2 Sb 2 O. [19][20][21] The BaAl 4 and ZrCuSiAs type phases have layer-like arrangements with layers of edge-sharing, oxygen-centered rare earth tetrahedra as common structural motif.…”

Section: Introductionmentioning

confidence: 90%

New quaternary arsenide oxides with square planar coordination of gold(i) – structure,¹⁹⁷Au Mössbauer spectroscopic, XANES and XPS characterization of Nd₁₀Au₃As₈O₁₀and Sm₁₀Au₃As₈O₁₀

et al. 2015

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The quaternary gold(I) arsenide oxides Nd10Au3As8O10 and Sm10Au3As8O10 were synthesized in sealed quartz ampoules from the rare earth (RE) elements, their appropriate sesquioxides, arsenic, arsenic(III) oxide and finely dispersed gold at maximum annealing temperatures of 1223 K. Both structures were refined from X-ray single crystal diffractometer data at room temperature and at 90 K. Nd10Au3As8O10 and Sm10Au3As8O10 crystallize with a new structure type that derives from the BaAl4 structure through distortions and formation of ordered vacancies. The structures consist of stacked polycationic [RE10O10](10+) layers with oxygen in tetrahedral rare earth coordination and polyanionic [Au(I)3(As2)4](10-) layers with gold in square planar or rectangular planar coordination of four arsenic dumbbells (255 pm As1-As2). In contrast to the well known ionic rare earth oxide layers, the gold arsenide layers rather show covalent bonding and account for the metallic nature of these two new arsenide oxides. This is confirmed by electronic structure calculations and resistivity measurements. The oxidation state of gold was investigated by (197)Au Mössbauer, X-ray absorption near edge structure (XANES) and photoelectron (XPS) spectroscopy. Due to missing comparative gold arsenide compounds, the monovalent gold phosphide oxides RE2AuP2O were measured for comparison. The XANES measurements additionally comprise monovalent gold arsenides REAuAs2. The XPS study contains BaAuAs as reference compound instead. Combination of all data clearly indicates Au(I), which was not observed in square planar coordination up to now. Temperature dependent magnetic susceptibility data show Curie-Weiss paramagnetism for Nd10Au3As8O10 and no magnetic ordering down to 2.5 K. Sm10Au3As8O10 shows the typical Van Vleck type paramagnetism for samarium compounds along with a transition to an antiferromagnetically ordered state at TN = 8.6 K.

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“…The charge could also be balanced, in theory, by anion vacancies in one of the sites; however, anion vacancies in these types of layered materials are not often observed, and the inclusion of the third anion allows the anion sites to remain fully occupied. Three anion materials are rare, with only a few known structure types exhibiting three chemically distinct anions. − …”

Section: Introductionmentioning

confidence: 99%

Bi_2+2nO_2+2nCu_2−δSe_2+n–δX_δ (X = Cl, Br): A Three-Anion Homologous Series

et al. 2018

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Both layered multiple-anion compounds and homologous series are of interest for their electronic properties, including the ability to tune the properties by changing the nature or number of the layers. Here we expand, using both computational and experimental techniques, a recently reported three-anion material, Bi4O4Cu1.7Se2.7Cl0.3, to the homologous series Bi2+2n O2+2n Cu2−δSe2+n–δXδ (X = Cl, Br), composed of parent blocks that are well-studied thermoelectric materials. All of the materials show exceptionally low thermal conductivity (0.2 W/mK and lower) parallel to the axis of pressing of the pellets, as well as narrow band gaps (as low as 0.28 eV). Changing the number of layers affects the band gap, thermal conductivity, carrier type, and presence of a phase transition. Furthermore, the way in which the different numbers of layers are accessed, by tuning the compensating Cu vacancy concentration and halide substitution, represents a novel route to homologous series. This homologous series shows tunable properties, and the route explored here could be used to build new homologous series out of known structural blocks.

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An Extension of Pnictide Oxide Chemistry – Salt Flux Synthesis and Structure of La₅Cu₄As₄O₄Cl₂

Cited by 17 publications

References 22 publications

Bi₄O₄Cu_1.7Se_2.7Cl_0.3: Intergrowth of BiOCuSe and Bi₂O₂Se Stabilized by the Addition of a Third Anion

Bi₄O₄Cu_1.7Se_2.7Cl_0.3: Intergrowth of BiOCuSe and Bi₂O₂Se Stabilized by the Addition of a Third Anion

New quaternary arsenide oxides with square planar coordination of gold(i) – structure,¹⁹⁷Au Mössbauer spectroscopic, XANES and XPS characterization of Nd₁₀Au₃As₈O₁₀and Sm₁₀Au₃As₈O₁₀

Bi_2+2nO_2+2nCu_2−δSe_2+n–δX_δ (X = Cl, Br): A Three-Anion Homologous Series

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An Extension of Pnictide Oxide Chemistry – Salt Flux Synthesis and Structure of La5Cu4As4O4Cl2

Cited by 17 publications

References 22 publications

Bi4O4Cu1.7Se2.7Cl0.3: Intergrowth of BiOCuSe and Bi2O2Se Stabilized by the Addition of a Third Anion

Bi4O4Cu1.7Se2.7Cl0.3: Intergrowth of BiOCuSe and Bi2O2Se Stabilized by the Addition of a Third Anion

New quaternary arsenide oxides with square planar coordination of gold(i) – structure,197Au Mössbauer spectroscopic, XANES and XPS characterization of Nd10Au3As8O10and Sm10Au3As8O10

Bi2+2nO2+2nCu2−δSe2+n–δXδ (X = Cl, Br): A Three-Anion Homologous Series

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An Extension of Pnictide Oxide Chemistry – Salt Flux Synthesis and Structure of La₅Cu₄As₄O₄Cl₂

Bi₄O₄Cu_1.7Se_2.7Cl_0.3: Intergrowth of BiOCuSe and Bi₂O₂Se Stabilized by the Addition of a Third Anion

Bi₄O₄Cu_1.7Se_2.7Cl_0.3: Intergrowth of BiOCuSe and Bi₂O₂Se Stabilized by the Addition of a Third Anion

New quaternary arsenide oxides with square planar coordination of gold(i) – structure,¹⁹⁷Au Mössbauer spectroscopic, XANES and XPS characterization of Nd₁₀Au₃As₈O₁₀and Sm₁₀Au₃As₈O₁₀

Bi_2+2nO_2+2nCu_2−δSe_2+n–δX_δ (X = Cl, Br): A Three-Anion Homologous Series