Decorative materials based on cobalt-containing akermanite

Bystrikov, A. S.; Gorbachev, V. V.; Orlov, D. L.; Petrakov, V. N.; Shishkin, I. V.

doi:10.1007/bf00702760

Cited by 2 publications

(3 citation statements)

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“…28 Another melilite (a˚kermanite, Ca 2 Mg-Si 2 O 7 ) was proposed as a blue pigment with cobalt doping up to 24% in weight. 29 This work was aimed at assessing the potential as ceramic pigment of cobalt-doped hardystonite by the solid-state synthesis, powder characterization (crystal structure and optical properties), and testing its technological behavior in ceramic coatings.…”

Section: Introductionmentioning

confidence: 99%

Co-Doped Hardystonite, Ca2(Zn,Co)Si2O7, a New Blue Ceramic Pigment

Dondi

Zanelli

Ardit

et al. 2010

Journal of the American Ceramic Society

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Raising cost, limited reserves, and toxicity make a pressing need to reduce the consumption of cobalt in the ceramic industry, trying to improve efficiency and sustainability of pigments. A novel blue colorant, based on the melilite structure, has been developed by searching for a ceramic pigment stable in very aggressive media, like the calcium- and zinc-rich glazes used in porous tiles (stoneware and monoporosa). Hardystonite was selected as a typical crystalline compound found in these coatings, which has just one four-fold crystallographic site where Co2+ ions can be accommodated, thus ensuring its unrivalled blue colour. Five samples (Ca2Zn1-xCoxSi2O7 with x = 0.05, 0.1, 0.2, 0.3 and 0.4) were prepared by solid state synthesis in industrial-like conditions (95% yield) and characterized by XRD, DRS, SEM-EDS and technological testing. Increasing cobalt doping gives rise to a gradual expansion of the hardystonite unit cell, unexpected on the basis of Zn2+ and Co2+ ionic radii, attributed to a change of the covalent character of M–O bonding. Optical spectra are dominated by the strong absorption bands of Co2+ in tetrahedral coordination (crystal field strength Dq = 421 cm-1, Racah B parameter = 793 cm-1). The best compromise between cobalt concentration and optical response was found to be around x = 0.3. The hardystonite pigment bestows a deep blue colour on glazes and glassy coatings, withstanding aggressive media rich in CaO and ZnO better than industrial blue pigments (cobalt aluminate, spinel) with similar colour efficiency than industrial blue dyes (cobalt silicate, olivine) but with the advantage to avoid specking defects of highly staining colorants

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Section: Introductionmentioning

confidence: 99%

Co-Doped Hardystonite, Ca2(Zn,Co)Si2O7, a New Blue Ceramic Pigment

Dondi

Zanelli

Ardit

et al. 2010

Journal of the American Ceramic Society

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“…For example, Si-and Ge-based melilite ceramics have excellent microwave dielectric [3][4][5][6][7][8][9][10][11][12][13][14] and optical properties 15,16 ; gallate melilites transformed by topotactic reduction can be used as 0D electrides 17 ; hardystonite Ca 2 ZnSi 2 O 7 is used as a biomaterial 18 doped with lanthanides-as phosphors 19,20 ; hardystonite and åkermanite Ca 2 MgSi 2 O 7 -as ceramic colorants. 21,22 Melilite-based glasses and glass-ceramics are used as a solid electrolyte sealant in high-temperature (HT) electrochemical devices. 23,24 It should be emphasized that Si-and B-based melilite-type compounds have a great potential as materials for microwave dielectric ceramics (e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

“…Melilite‐type compounds draw attention due to their thermal, optical, piezo‐, and ferroelectric properties. For example, Si‐ and Ge‐based melilite ceramics have excellent microwave dielectric 3–14 and optical properties 15,16 ; gallate melilites transformed by topotactic reduction can be used as 0D electrides 17 ; hardystonite Ca 2 ZnSi 2 O 7 is used as a biomaterial 18 doped with lanthanides—as phosphors 19,20 ; hardystonite and åkermanite Ca 2 MgSi 2 O 7 —as ceramic colorants 21,22 . Melilite‐based glasses and glass‐ceramics are used as a solid electrolyte sealant in high‐temperature (HT) electrochemical devices 23,24 .…”

Section: Introductionmentioning

confidence: 99%

Topotactic transformation of gadolinite‐ to melilite‐type structure revisited

Gorelova,

Vereshchagin,

Shagova

et al. 2024

J Am Ceram Soc.

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Topotactic reactions can lead to the formation of new phases, which cannot be obtained via classical synthesis methods. The high‐temperature topotactic transformation of gadolinite‐type compounds, homilite Ca2Fe2+B2Si2O8O2 and datolite Ca2□B2Si2O8(OH)2, into a melilite‐type compound, okayamalite Ca2B2SiO7, was studied by in situ high‐temperature single‐crystal X‐ray diffraction and ex situ Raman spectroscopy. Furthermore, the density functional theory was used to calculate the electronic structures and Raman spectra of datolite, homilite, and okayamalite. At low temperatures (250–500°C), homilite undergoes the Fe oxidation process, whereas at high temperatures, both homilite and datolite transform into okayamalite (750 and 780°C, respectively). The transformation of datolite into okayamalite is a conversion of a single crystal to a polycrystalline aggregate, while the transformation of homilite into okayamalite is a transformation of a single crystal to a single crystal. Datolite derived from okayamalite is similar to natural okayamalite, whereas homilite derived from okayamalite shows Fe3+ for Si/B substitution. The existence of tetrahedrally coordinated Fe3+ leads to a stabilizing effect, resulting in the formation of a single crystal of okayamalite. In addition, the incorporation of iron into the structure of okaymalite leads to a change in the thermal behavior of the compound (α11 = 22 and 15×10−6°C–1 for datolite‐derived and homilite‐derived okayamalites, respectively). However, the thermal expansion of okayamalites is almost isotropic, which is typical for melilite‐type compounds.datolite, high‐temperature, homilite, okayamalite, topotactic reaction

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Decorative materials based on cobalt-containing akermanite

Cited by 2 publications

References 0 publications

Co-Doped Hardystonite, Ca2(Zn,Co)Si2O7, a New Blue Ceramic Pigment

Co-Doped Hardystonite, Ca2(Zn,Co)Si2O7, a New Blue Ceramic Pigment

Topotactic transformation of gadolinite‐ to melilite‐type structure revisited

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