Iono‐Covalent Character of the Metal–Oxygen Bonds in Oxides: A Comparison of Experimental and Theoretical Data

Lenglet, M.

doi:10.1080/0882751031000116142

Cited by 31 publications

(8 citation statements)

References 127 publications

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“…In class I hybrid materials there are weak interactions – namely, van der Waals (vdW), hydrogen bonding, and electrostatic interactions – between the components (Scheme , a) 2. Class II hybrid materials display strong bonding (i.e., covalent or iono‐covalent interactions, Scheme , b;2 iono‐covalent interactions are covalent bonds with a considerable ionic character often found, e.g., in binary or mixed metal oxides) 8. In class II hybrids, the strong interactions might of course be accompanied by weak interactions characteristic of class I hybrids 2…”

Section: Definition Of “Inorganic‐organic Hybrid Material” and “Grmentioning

confidence: 99%

Green Synthesis of Inorganic–Organic Hybrid Materials: State of the Art and Future Perspectives

Unterlass

2016

Eur J Inorg Chem

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The term "inorganic-organic hybrid materials" designates inorganic building blocks in the colloidal domain (1-1000 nm) embedded in an organic, typically polymeric, matrix. Owing to their outstanding properties, hybrid materials have the potential to improve human life significantly. In the last two decades, the importance of reorienting chemical syntheses in the direction of more sustainable, less harmful and energy-consuming procedures, referred to as green chemistry, has been[a] defines a hybrid material as a "material composed of an intimate mixture of inorganic components, organic components, or both types of components", noting that "the components typically interpenetrate on scales of less than 1 μm". [6] This definition includes, for example, polymer-polymer composites (aka blends), metal-metal composites, metal-ceramic composites, metal-polymer, and ceramic-polymer composites. The plethora of powerful hybrid materials cannot be covered in one review article. This paper will thus focus on one subclass of hybrid materials: namely, inorganic-organic hybrid materials in which the amount of organic polymeric component is a majority over that of the inorganic component. Note that the term "composite" historically tends to be associated with macroscopic hybrid materials with the dispersed phase typically greater than 1 mm. Others associate "composite" with hybrid materials in which the components interact through noncovalent bonding, and "hybrids" with cases in which the components are connected by covalent bonding. [7] In recent years, this distinction has faded more and more, and both terms are often used interchangeably. This review addresses exclusively inorganic-organic hybrid materials with the minor component in the colloidal range, and the term "composite" is used occasionally.Depending on the strength of interaction between the dispersed inorganic phase and the organic matrix, hybrid materials are commonly subdivided into two categories. [2] In class I hybrid materials there are weak interactions -namely, van der Waals (vdW), hydrogen bonding, and electrostatic interactions -between the components (Scheme 1, a). [2] Class II hybrid materials display strong bonding (i.e., covalent or iono-covalent interactions, Scheme 1, b; [2] iono-covalent interactions are covalent bonds with a considerable ionic character often found, e.g., in binary or mixed metal oxides). [8] In class II hybrids, the strong Eur.

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Section: Definition Of “Inorganic‐organic Hybrid Material” and “Grmentioning

confidence: 99%

Green Synthesis of Inorganic–Organic Hybrid Materials: State of the Art and Future Perspectives

Unterlass

2016

Eur J Inorg Chem

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“…On the right side, a representation of each polyhedron with their respective ligands and the occupancy of the dopants (i.e., Ni 2+ and Ti 4+ ; for further details see next sections). Figure obtained by means of the VESTA v.3.2.1 visualizer …”

Section: Introductionmentioning

confidence: 99%

Ni‐Ti Codoped Hibonite Ceramic Pigments by Combustion Synthesis: Crystal Structure and Optical Properties

et al. 2016

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Hibonite (CaAl12O19, space group [s.g.] P63/mmc) has the structural formula A[XII]M1[VI] M2[V]M32[IV]M42[VI]M56[VI]O19, where Ca is 12‐fold coordinated at site A and Al3+ ions are distributed over five different sites: three distinct octahedra [M1 (point symmetry D3d), M4 (C3v) and M5 (Cs)], the M3 tetrahedron (C3v), and the unusual fivefold coordinated trigonal bipyramid M2 (D3h). Hibonite is able to accommodate a wide range of ions with different valence and coordination, making its structure a promising ceramic pigment. One of the main challenges is to understand and control incorporation mechanisms and the threshold of chromophores solubility. It is known that M2+ ions tend to be hosted at the M3 site, while M4+ ions are preferentially accommodated at the M4 site: the introduction of divalent ions might be promoted by the associated incorporation of tetravalent cations, which ensure the lattice electroneutrality and are ordered over the M4 face‐sharing octahedral dimers. In this work, the mechanism of the coupled substitution 2Al3+→(Ni2++Ti4+) was investigated by combining X‐ray powder diffraction and diffuse reflectance spectroscopy techniques. Hibonite turquoise pigments with increasing Ni+Ti doping (CaAl12‒2xNixTixO19 where x = 0.1‒2.0 apfu) were prepared by combustion synthesis, utilizing a fuel mixture (urea, glycine, β‐alanine) set up according to their compatibility with metal nitrates used as raw materials. The ignition temperature of combustion reaction was 400°C, but samples underwent an additional annealing at 1200°C. Samples up to x = 0.4 are monophasic; for higher doping, hibonite is the main component accompanied by growing percentages of spinel and perovskite phases. The Ni and Ti addition induced a regular increase in the hibonite unit‐cell parameters until x = 1.0, that is proportional to the amount and difference in ionic radii of dopants. In particular, an elongation of the 〈M–O〉 bond distances of both M3 and M4 sites was observed. In terms of optical parameters, Ni2+ is preferentially incorporated in tetrahedral coordination, up to 0.3 apfu at the M3 site, and at the M4 octahedron as well (up to 0.19 apfu). The crystal field strength of fourfold coordinated Ni2+ is regularly decreasing, implying an elongation of the local Ni–O bond that is coherent with the volume increasing from AlO4 to NiO4 tetrahedra registered by XRD. Ti4+ ions are accommodated at both the M2 and M4 octahedra which expand proportionally to the amount of dopants. Pigment purity and color strength vary with doping depending on the multistep mechanism of Ni and Ti incorporation in the hibonite lattice.

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“…Refractive index of oxide (Dimitrov and Sakka 1996) Band gap of oxide (Dimitrov and Sakka 1996) Assumed in Λ χav and Λ ICP calcs. Table 3 and/or described in text (b) cation polarizability back-calculated from ionic refractivity from reference listed using equation B.5 (c) estimated values for ICP OB since calculations from ionic radii produce negative numbers (see text) (d) Duffy's (2006) most recent values for first row transition metals obtained by "pragmatic means" (e) average value from refractive index and energy gap or glass refractivity and oxide refractive index (f) Lenglet's (2004) values based on consideration of acidity, fractional iconicity, and periodic trends in metal oxides (g) Mills' (1995) values based on consideration of molar refractivity, electron densities, and heat of formation (h) provisional values (see text) (j) value due to combination of trigonal bipryamidal (TeO 4 ) and trigonal pyramidal (TeO 3 ) units. Most glasses will have a mix.…”

Section: B5 Conclusionmentioning

confidence: 99%

Optical Basicity and Nepheline Crystallization in High Alumina Glasses

Rodriguez¹,

McCloy²,

Schweiger³

et al. 2011

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SummaryThe purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO 4 ) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator.Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimental basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV.To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage.Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.v

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Iono‐Covalent Character of the Metal–Oxygen Bonds in Oxides: A Comparison of Experimental and Theoretical Data

Cited by 31 publications

References 127 publications

Green Synthesis of Inorganic–Organic Hybrid Materials: State of the Art and Future Perspectives

Green Synthesis of Inorganic–Organic Hybrid Materials: State of the Art and Future Perspectives

Ni‐Ti Codoped Hibonite Ceramic Pigments by Combustion Synthesis: Crystal Structure and Optical Properties

Optical Basicity and Nepheline Crystallization in High Alumina Glasses

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