Syntheses of selenian valleriite

Takeno, Setsuo; Moh, G. H.

doi:10.1007/bf01164606

Cited by 8 publications

(10 citation statements)

References 4 publications

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“…The precursors spontaneously self-assemble into alternating quasi-atomic Cu-Fe-S sulfide and Mg hydroxide sheets in the hydrothermal process through a mechanism that still needs to be understood. The structure of valleriites formed by incommensurate 2D layers allows to vary widely, and to some extent independently, their composition and then properties, including replacement both of metals and chalcogenide atoms [30][31][32][33][34][42][43][44][45][46][47][48][49][50]. On the other hand, the counterparts affect each other via the electric charges and probably other factors; this makes possible to finely adjust the material characteristics.…”

Section: Discussionmentioning

confidence: 99%

“…Attempts to synthesize valleriite via thermal sintering or hydrothermal route have been undertaken [30,[35][36][37]41,42] but produced mixtures of valleriite (less than 50%) with chalcopyrite, magnetite and other by-products. In recent years, a number of similar composites with the layered structure constructed by iron selenide and lithium-based hydroxides (Li1-xFex)(OH)FeSe [43][44][45][46][47] have been prepared and studied as superconductors with the critical temperature Tc up to 40 K. Such materials as [(Fe,Al)(OH)2][FeSe]1.2 [48],…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Mikhlin¹,

Борисов

Vorobyev³

et al. 2022

Preprint

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We introduce here a multifunctional material composed of alternating atomic sulfide sheets close to CuFeS2 and Mg-based hydroxide ones (valleriite), which are assembled due to their electric charges of opposite sign. Valleriite particles of 50-200 nm in the lateral size and 10-20 nm thick were synthesized via a simple hydrothermal pathway using various concentrations of precursors and dopants, and examined with XRD, TEM, EDS, X-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy (REELS), Mössbauer, Raman and UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The electronic, magnetic and optical characteristics are found to be critically dependent of the charge (electron density) at the narrow-gap sulfide layers containing Cu+ and Fe3+ cations, and can be tuned via the composition of hydroxide part. Particularly, substitution of Mg2+ with Al3+ increases the negative charge of the hydroxide layers and reduces the content of Fe3+-OH centers (10-45% of total iron); the effects of Cr and Co dopants entering both layers are more complicated. Mössbauer doublets of paramagnetic Fe3+ detected at room temperature transform to several Zeeman sextets at 4.2 K; the hyperfine fields up to 500 kOe and complex magnetic behavior, but not pure paramagnetism or antiferromagnetism, were observed for valleriites with the higher positive charge of the sulfide sheets, probably due to the depopulation of the minority-spin 3d states of S-bonded Fe3+ ions. Aqueous colloids of valleriite show optical absorption at 500 - 750 nm, which, along with the peaks at the same energies in REELS, may arise due to quasi-static dielectric resonance involving the vacant Fe 3d band and being dependent on the composition of both layers too. These and other findings call attention to the of valleriites as a new rich family of 2D materials for a variety of potential applications.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Mikhlin¹,

Борисов

Vorobyev³

et al. 2022

Preprint

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“…Attempts to synthesize valleriite via thermal sintering or a hydrothermal route have been undertaken 33,[38][39][40]44,45 but they produced mixtures of valleriite (less than 50%) with chalcopyrite, magnetite and other by-products. In recent years, a number of similar composites with a layered structure constructed by iron selenide and lithium-based hydroxides (Li 1Àx -Fe x )(OH)$FeSe [46][47][48][49][50] have been prepared and studied as superconductors with the critical temperature T c up to 40 K. Materials such as [(Fe,Al)(OH) 2 ][FeSe] 1.2 , 51 [(Li 0.8 Fe 0.2 )OH] Fe(S 1Àx Se x ), 52 (Na x Fe 1-x )(OH)FeS 53 and intercalated iron chalcogenides 54 were also obtained in efforts, though unsuccessful yet, to enhance the T c .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu–Fe sulfide and Mg-based hydroxide

et al. 2022

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“…Exact nature of Fe species, as well as many properties of natural valleriites, remain uncertain due to complex composition of the mineral assemblages. The attempts to synthesize valleriite via thermal sintering or hydrothermal routes have been undertaken [30,[35][36][37]41,42] but mixtures of valleriite with chalcopyrite, magnetite and other byproducts have been obtained. It should be noted that a number of layered composites of lithiumbased and some other hydroxides and iron selenides (Li1-xFex)(OH)FeSe, [43][44][45][46][47] [(Fe,Al)(OH)2][FeSe]1.2, [48] iron sulfides [(Li0.8Fe0.2)OH]Fe(S1-xSex), [49] (NaxFe1-x)(OH)FeS [50] and similar [51] have been prepared and studied with focus on their superconductivity (critical temperature Tc up to 40 K).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Mikhlin¹,

Борисов

Vorobyev³

et al. 2021

Preprint

View full text Add to dashboard Cite

Two-dimensional phenomena are attracting enormous interest at present and the search for novel 2D materials is very challenging. We propose here the layered material valleriite composed of altering atomic sheets of Cu-Fe sulfide and Mg-based hydroxide synthesized via a simple hydrothermal pathway as particles of 50-200 nm in the lateral size and 10-20 nm thick. The solid products and aqueous colloids prepared with various precursor ratios were examined using XRD, TEM, EDS, X-ray photoelectron spectroscopy (XPS), reflection electron energy loss spectroscopy (REELS), Raman, Mössbauer, UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The material properties are largely determined by the narrow-gap (less than 0.5 eV) sulfide layers containing Cu+ and Fe3+ cations, monosulfide and minor polysulfide anions but are strongly affected by the hydroxide counterparts. Particularly, Fe distribution between sulfide (55-90%) and magnesium hydroxide layers is controlled through insertion of Al into the hydroxide part and by Cr and Co dopants entering both layers. Room-temperature Mössbauer signals of paramagnetic Fe3+ transformed to several Zeeman sextets with hyperfine magnetic fields up to 500 kOe in the sulfide layers at 4 K. Paramagnetic or more complicated characters were observed for valleriites with higher and lower Fe concentrations in hydroxide sheets, respectively. Valleriite colloids showed negative zeta potentials, suggesting negative electric charging of the hydroxide sheets, and optical absorption maxima between 500 nm and 700 nm, also depended on the Fe distribution. The last features observed also in the REELS spectra may be due to localized surface plasmon or, more likely, quasi-static dielectric resonance. The tunable composition, electronic, magnetic, optic and surface properties highlight valleriites as a rich platform for novel 2D composites promising for numerous applications.

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Syntheses of selenian valleriite

Cited by 8 publications

References 4 publications

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu–Fe sulfide and Mg-based hydroxide

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

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