Phase formation studies and crystal structure refinements in the Mn<sup>II</sup>/Te<sup>IV</sup>/O/(H) system

Weil, Mat­thias; Eder, Felix

doi:10.1002/zaac.202200205

Cited by 5 publications

(7 citation statements)

References 54 publications

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“…A reproducible synthesis of the title compound obtained 30 years ago proved to be very difficult, not only because the reported fluid loss within the hydrothermal experiment is quite difficult to control, but also because the variable (Cu,Mn) ratio was at that time deliberately used for the synthesis of the of the Cu-substituted denningites. Although inserting only starting materials with Mn in the divalent state, redox reactions within the hydrothermal fluid is known to produce Mn III -bearing reaction products, as even manifested through recent investigations on phases in the system Mn II O-Te IV O2 (Eder & Weil 2022). Within the scope of attempts to reproduce K-(Cu,Mn) phases, we indeed obtained zemannite-type phases, apparently with a twofold superstructure, but not exhibiting such a strong distortion of the unit-cell.…”

Section: Discussionmentioning

confidence: 99%

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

Eder

Weil

Miletich

2022

Preprint

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Synthetic single crystals of K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O were obtained from an overconcentrated alkaline aqueous solution in the system K2O-MnO-CuO-TeO2 under hydrothermal conditions at T ≤ 220 °C. Subeuhedral single crystals have been investigated crystallographically by means of single-crystal X-ray diffraction. The crystal structure of this new zemannite-type representative follows a monoclinic twofold superstructure. The doubling of the unit-cell volume is accompanied by a hexagonal-to-monoclinic symmetry reduction, resulting in threefold twinning with individual crystal domains following the space group symmetry P21. Refinements of site-occupation factors and the evaluation of bond valences suggest a distribution of di- and trivalent cations on the octahedral M sites with a ratio (CuII+MnII) : MnIII approximating 1 : 1. From arguments about the cation sizes and the individual bond valence sums, a distribution of CuII1–xMnIIIx and MnIIx MnIII1–x at each two of the four M positions can be assumed with a presumed x between ~0.14 and ~0.50. The K+ cations and crystal water molecules inside the channels are located off the central channel axis. In contrast to most other known zemannite-type phases, the extra-framework atoms show full site occupations and are not disordered. The distribution of the channel contents supports the anisotropic deformation of the surrounding framework, which follows the local symmetry reduction as required for the Jahn-Teller distortion of the octahedrally coordinated M sites within the framework. The arrangement of the deformed channels can be understood as the origin of the existing superstructure.

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Section: Discussionmentioning

confidence: 99%

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

Eder

Weil

Miletich

2022

Preprint

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“…Whereas the results of single-crystal structure analyses were inconspicuous for α-MnTeO 3 , γ-MnTeO 3 , Mn 6 Te 5 O 16 and Mn 15 (TeO 3 ) 14 (OH) 2 [14], those of the channelstructure of hexagonal Mn 3 (TeO 3 ) 2 (OH) 2 revealed some unsatisfactory features of the refined crystal structure model, in particular, high remaining electron densities located within the channels. Preliminary experiments indicated that the height of the remaining electron density depends on the metal salt used as the source for manganese(II) in the hydrothermal experiment, and that corresponding anions (CO 3 2− , SO 4 2− , SeO 4 2− , NO 3 − , Cl − , Br − ) can be incorporated into the channels where they partly substitute the prevalent OH − species.…”

Section: Introductionmentioning

confidence: 91%

“…With the objective to prepare different phases in the Mn II /Te IV /O/(H) system in the form of single-phase material, we started systematic studies of the phase formation in this system using solid-state or hydrothermal reactions. Although we were eventually able to grow single-crystals and to determine the crystal structures of α-MnTeO 3 , γ-MnTeO 3 , Mn 6 Te 5 O 16 , Mn 15 (TeO 3 ) 14 (OH) 2 and Mn 3 (TeO 3 ) 2 (OH) 2 , the intended phase purity could not be achieved because all products consisted of mixtures of different phases [14].…”

Section: Introductionmentioning

confidence: 99%

The Family of MII3(TeIVO3)2(OH)2 (M = Mg, Mn, Co, Ni) Compounds—Prone to Inclusion of Foreign Components into Large Hexagonal Channels

et al. 2022

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MII3(TeIVO3)2(OH)2 (M = Mg, Mn, Co, Ni) compounds crystallize isotypically in the hexagonal space group P63mc (No. 186) with unit-cell parameters of a » 13 Å, c » 5 Å. In the crystal structure, a framework with composition M3(TeO3)2(OH)1.50.5+ defines large hexagonal channels extending along [001] where the remaining OH– anions are located. Crystal-growth studies under mild hydrothermal conditions with subsequent structure analyses on basis of X-ray diffraction methods revealed that parts of other anions present in solution such as CO32–, SO42–, SeO42–, NO3–, Cl– or Br– could partly replace the OH– anions in the channels. The incorporation of such anions into the M3(TeO3)2(OH)2 structure was confirmed by energy-dispersive X-ray spectrometry (EDS) measurements and Raman spectroscopy of selected single-crystals.

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“…A reproducible synthesis of the title compound obtained 30 years ago proved to be very difficult, not only because the reported fluid loss within the hydrothermal experiment is quite difficult to control, but also because the variable (Cu,Mn) ratio was at that time deliberately used for the synthesis of the of the Cu-substituted denningites. Although inserting only starting materials with Mn in the divalent state, redox reactions within the hydrothermal fluid is known to produce Mn III -bearing reaction products, as even manifested through recent investigations on phases in the system Mn II O-Te IV O 2 (Eder and Weil 2022). During attempts to reproduce K-(Cu,Mn) phases, we indeed obtained zemannite-type phases, apparently with a twofold superstructure, but not exhibiting such a strong distortion of the unit-cell.…”

Section: Mn IIImentioning

confidence: 99%

“…Acknowledgements This article is dedicated to Prof. Josef Zemann (1923-2022 on the occasion of the 100th anniversary of his birthday. Constructive reviews by two anonymous experts and comments by editor Thomas Armbruster and editor-in-chief Lutz Nasdala are gratefully acknowledged.…”

Section: Supplementary Informationmentioning

confidence: 99%

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

2023

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Synthetic single crystals of K[(CuII,MnII,MnIII)2(TeO3)3]·2H2O were obtained from an overconcentrated alkaline aqueous solution in the system K2O-MnO-CuO-TeO2 under hydrothermal conditions at T ≤ 220 °C. Subeuhedral single crystals have been investigated by means of single-crystal X-ray diffraction. The crystal structure of this new zemannite-type representative adopts a monoclinic twofold superstructure. The doubling of the unit-cell volume is accompanied by a hexagonal-to-monoclinic symmetry reduction, resulting in threefold twinning with individual crystal domains following the space group symmetry P21. Refinements of site-occupation factors and the evaluation of bond valences suggest a distribution of di- and trivalent cations at the octahedrally coordinated M sites with a ratio (CuII + MnII):MnIII approximating 1:1. Based on arguments about the cation sizes and the individual bond valence sums, a distribution of CuII1–xMnIIIx and MnIIx MnIII1–x at each two of the four M sites can be assumed with x between ~ 0.14 and ~ 0.50. The K+ cations and H2O molecules inside the channels are located off the central channel axis. In contrast to most other known zemannite-type phases, the extra-framework atoms show full occupancies and are not disordered. The distribution of the channel contents supports the anisotropic deformation of the surrounding framework, which follows the local symmetry reduction as required for the Jahn-Teller distortion of the octahedrally coordinated M sites within the framework. The arrangement of the deformed channels can be understood as the origin of the existing superstructure.

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Phase formation studies and crystal structure refinements in the Mn^II/Te^IV/O/(H) system

Cited by 5 publications

References 54 publications

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

The Family of MII3(TeIVO3)2(OH)2 (M = Mg, Mn, Co, Ni) Compounds—Prone to Inclusion of Foreign Components into Large Hexagonal Channels

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

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Phase formation studies and crystal structure refinements in the MnII/TeIV/O/(H) system

Cited by 5 publications

References 54 publications

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

The Family of MII3(TeIVO3)2(OH)2 (M = Mg, Mn, Co, Ni) Compounds—Prone to Inclusion of Foreign Components into Large Hexagonal Channels

K[(CuII,MnII,MnIII)2(TeO3)3]∙2H2O, the first zemannite-type structure based on a Jahn-Teller-distorted framework

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Phase formation studies and crystal structure refinements in the Mn^II/Te^IV/O/(H) system