Structure of the cyclic barium copper silicate Ba2Cu2[Si4O12] at 300 K

Janczak, Jan; Kubiak, R.L.

doi:10.1107/s0108270191002354

Cited by 9 publications

(3 citation statements)

References 3 publications

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“…The same authors alternatively proposed I4/mmm but considered this solution worse because of large displacement parameters for the oxygen atoms. Basically the same centrosymmetric solution was reported by Janczak and Kubiak (1992). Finally, a further, improved structure model was proposed by Sparta and Roth (2004) for BaCuSi 2 O 6 at room temperature with a larger unit cell in space group I4 1 /acd with Z = 16 and a = 10.009(2), c = 22.467(6) Å.…”

Section: Introductionmentioning

confidence: 59%

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

2015

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A new silicate, colinowensite, BaCuSi2O6, has been found in the Wessels mine, Kalahari Manganese Field, South Africa. It is associated with effenbergerite, wesselsite, lavinskyite, scottyite, diegogattaite, as well as with pectolite, quartz, aegirine, richterite, minerals of the garnet group and a number of different manganese and iron oxides, especially hausmannite and hematite. The mineral was named for the mineral collector and finder of the new species, Colin R. Owens, of Somerset West, South Africa. Colinowensite is brittle, with uneven fracture, and the estimated Mohs hardness is ∼4. It occurs as subhedral crystals <100 μm in size. The forms {100} and {110} are observed while {001} is always present in cleavage plates. The calculated density is 4.236 g cm–3. It is the natural analogue of the synthetic pigmentreferred to as Chinese or Han purple, which is found on artifacts from ancient and imperial China. The mineral is of dark blue to purple colour, with a purple streak, and is uniaxial (–), with ω = 1.740 (20), ε = 1.735 (20) (420 nm) and ω = 1.745 (20), ε = 1.730(20) (650 nm). The lustre is vitreous and no fluorescence is observed under either shortwave or longwave ultraviolet radiation. Avery strong pleochroism occurs from purple along the c axis to blue in a perpendicular direction. Colinowensite is not soluble in acids except HF. Electron microprobe analyses gave an average composition (wt.%) of CuO 22.53, BaO 43.43 and SiO2 34.04 yielding the empirical formula (based on 6 O a.p.f.u.) BaCuSi2O6. The new mineral is tetragonal, space group I41/acd with Z = 16, anda = 9.967(1), c = 22.290 (2) Å. Colinowensite is a cyclosilicate with [Si4O12]8– 4-membered single rings, arranged in sheets parallel to (001). The structure is further characterized by CuO4 squares sharing corners with four neighbouring silicate rings within a sheet. Ba2+ cations are bonded to ten O atoms in irregular coordination. Average Si–O, Cu–O and Ba–O bond lengths are 1.619, 1.934 and 2.943 Å, respectively. Colinowensite belongs to subdivision 9. CE of the Strunz Mineralogical Tables. In addition, based on single-crystal X-ray work, new structural data for wesselsite of chemical composition Sr0.9Ba0.1CuSi4O10 are provided.

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Section: Introductionmentioning

confidence: 59%

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

2015

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“…To gain more insight into the local structure of AE CuSi 4 O 10 , the BaCuSi 2 O 6 compound that has the same chromophore group, but a different crystal structure, was also investigated. BaCuSi 2 O 6 is known by the mineral name colinowensite ; its crystal structure was initially described in the I 4̅2 m or I 4/ mmm space groups, but subsequent investigations ascertained that this compound crystallizes in the tetragonal I 4 1 / acd space group at room temperature. , It is characterized by two very interesting structural features: (1) isolated 4-rings of tetrahedra and (2) a square-corrugated coordination of the Cu 2+ ions forming Cu–Cu dimers parallel to the c axis (Figure S8).…”

Section: Resultsmentioning

confidence: 99%

Structure Dynamics and Vibronic Coupling in AECuSi₄O₁₀ (AE: Ca, Sr, Ba) Compounds

Martinelli,

Sartori,

Campolucci

et al. 2023

Chem. Mater.

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Alkaline earth copper silicate-based pigments are compounds of interest from a historical point of view, thanks to their interesting near-infrared (NIR) photoemission. It is well recognized that the emission originates from the Cu2+ d–d transitions inside the chromophore group [CuO4]6–; however, the optical properties are slightly different, probably related to a variation in the local structure. Here, we report detailed X-ray powder diffraction and pair distribution function analysis of AECuSi4O10 (AE = Ca2+, Sr2+, Ba2+) silicates. Remarkably, our investigation shows that all of these compounds are characterized by a complex structural dynamic involving the [SiO4]4– tetrahedral framework embedding the [CuO4]6– chromophore group. This structure dynamics induces a vibronic coupling, allowing the d–d transitions responsible for the characteristic color of the compounds as well as a strong vibronic broadening of the electronic states. As a consequence, the absorption and emission spectra in the visible and NIR range are influenced by the alkaline earth metal and are characterized by broad bands and display the Stokes shift typically observed in vibronic systems.

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“…Likewise, many minerals exhibit novel structures that contain interesting nanosized Cu−O frameworks. Table lists some examples from a large class of existing compounds as well as some phases newly synthesized in our laboratory. − Figure shows the structure of shattuckite, Cu 5 (SiO 3 ) 4 (OH) 2 , which contains brucite-like (CuO 2 ) n layers built up from edge-shared octahedra . The CuO 6 octahedron adopts the [4 + 2] Jahn−Teller distortion where the two long bonds are 2.59 Å ( k × 2, for Cu(1)), 2.62 Å, and 2.31 Å (P, Q for Cu(2)), much longer than 1.96 Å, 1.98 Å ( i × 2, j × 2), and 1.93−2.05 Å (L∼O) of the four short bonds, respectively.…”

Section: On Extended Solidsmentioning

confidence: 99%

Structurally Confined Transition-Metal Oxide Layers, Chains and Oligomers in Molecular and Extended Magnetic Solids

Hwu

1998

Chem. Mater.

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In an attempt to abstract the structural units of widely known silicate, phosphate, and arsenate compounds based on a transition-metal oxide (TM oxide) framework, we have gained some new insight into the study of “nanostructured” materials and their corresponding electronic and magnetic properties. In this review, we highlight some of the features associated with the nanosized TM oxide frameworks observed in this special class of oxides. Structurally, these oxides adopt a mixed framework that is composed of interlinked MO6 (M = transition-metal cation) octahedra and XO4 (X = Si4+, P5+, As5+) tetrahedra. TM oxide octahedra may share vertexes, edges, and faces to form nanoscale layers, chains, and oligomers. These structurally well-defined low-dimensional lattices are of experimental and theoretical importance in the sense that electron interaction can be studied in a confined space. In this review, we will illustrate these structurally confined TM oxide frameworks, including those observed in molecular complexes.

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Structure of the cyclic barium copper silicate Ba2Cu2[Si4O12] at 300 K

Cited by 9 publications

References 3 publications

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

Structure Dynamics and Vibronic Coupling in AECuSi₄O₁₀ (AE: Ca, Sr, Ba) Compounds

Structurally Confined Transition-Metal Oxide Layers, Chains and Oligomers in Molecular and Extended Magnetic Solids

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Structure of the cyclic barium copper silicate Ba2Cu2[Si4O12] at 300 K

Cited by 9 publications

References 3 publications

Colinowensite, BaCuSi2O6, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi4O10

Colinowensite, BaCuSi2O6, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi4O10

Structure Dynamics and Vibronic Coupling in AECuSi4O10 (AE: Ca, Sr, Ba) Compounds

Structurally Confined Transition-Metal Oxide Layers, Chains and Oligomers in Molecular and Extended Magnetic Solids

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Product

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Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

Colinowensite, BaCuSi₂O₆, a new mineral from the Kalahari Manganese Field, South Africa and new data on wesselsite, SrCuSi₄O₁₀

Structure Dynamics and Vibronic Coupling in AECuSi₄O₁₀ (AE: Ca, Sr, Ba) Compounds