Irreversible spectral changes of cobalt(II) by moderate heating in sol-gel glasses, and their ligand field rationalization

Reisfeld, R.; Chernyak, Valery; Eyal, M.; Jørgensen, C.K.

doi:10.1016/0009-2614(89)85034-1

Cited by 21 publications

(4 citation statements)

References 27 publications

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“…It is worth noting that the assembly mixture should be tailored in order to produce ions with specific coordination number since the ion geometry will affect its final distribution in the IO. In the example of Co, excess HCl is required to favor the tetrahedral rather than octahedral coordinated form of Co(II), while moderately acidic conditions (0.03 m HCl) lead to an uneven IO film containing blackened cobalt oxide within the silica matrix. At elevated concentrations of HCl (0.63 m ), a uniform blue cobalt silicate matrix is obtained, likely due to the formation of tetrahedral cobalt chloride, which facilitates its incorporation into the tetrahedral silica matrix during condensation of tetraethyl orthosilicate (TEOS) .…”

Section: Controlled Localization Of Catalytic Sitesmentioning

confidence: 99%

Modular Design of Advanced Catalytic Materials Using Hybrid Organic–Inorganic Raspberry Particles

Shirman

Shneidman

et al. 2017

Adv Funct Materials

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Catalysis is one of the most sophisticated areas of materials research that encompasses a diverse set of materials and phenomena occurring on multiple length and time scales. Designing catalysts that can be broadly applied toward global energy and environmental challenges requires the development of universal frameworks for complex catalytic systems through rational and independent (or quasi-independent) optimization of multiple structural and compositional features. Toward addressing this goal, a modular platform is presented in which sacrificial organic colloids bearing catalytic nanoparticles on their surfaces self-assemble with matrix precursors, simultaneously structuring the resulting porous networks and fine-tuning the locations of catalyst particles. This strategy allows combinatorial variations of the material building blocks and their organization, in turn providing numerous degrees of freedom for optimizing the material's functional properties, from the nanoscale to the macroscale. The platform enables systematic studies and rational design of efficient and robust systems for a wide range of catalytic and photocatalytic reactions, as well as their integration into industrial and other real-life environments.

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Section: Controlled Localization Of Catalytic Sitesmentioning

confidence: 99%

Modular Design of Advanced Catalytic Materials Using Hybrid Organic–Inorganic Raspberry Particles

Shirman

Shneidman

et al. 2017

Adv Funct Materials

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“…Figure 1. Schematic diagram of high-temperature visible spectrometer system: (1) 400-W halogen lamp (Philips); (2) quartz lens;(3) temperature controlling unit (Chino); (4) electric furnace equipped with quartz lens windows;(5) specimen; (6) chopper (Optics); (7) grating monochromator (G-250, Nikon); (8) photomultiplier (R376, Hamamatsu); (9) driving unit (Nikon); (10) lock-in amplifier (Optics); (11) digital voltmeter (Iwatsu); (12) personal computer (PC-8801, NEC);(13) X-Y plotter (Graphtic).…”

mentioning

confidence: 99%

Optical and magnetic properties of cobalt(2+) ions in dried and heated silica gels prepared by the sol-gel process

Kojima¹,

Taguchi²,

Matsuda³

1991

J. Phys. Chem.

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“…A comparison of the energies (ϳ17,200 cm 21 and 7400 cm 21 ) and molar extinction coefficient values (ϳ50 and 4.5 litre mole 21 cm 21 ) of the observed visible and NIR absorption bands of Co(II) in the case of parent borosilicate glass with those of Co(II) ion in known coordination [5][6][7][8][9][10][11][12] suggests that the ions in this glass are in tetrahedral fourfold coordination.…”

Section: A Absorption Spectramentioning

confidence: 99%

“…A trigonal distortion of a T d field structure which lowers the symmetry to D 2d is most common 6,[9][10][11] ; in the case of Co(II) in solids and departure from tetrahedral symmetry usually occur due to a difference in bond distances of the tetrahedron. interaction effect alone.…”

Section: A Absorption Spectramentioning

confidence: 99%

A study on the migration of Co(II) and Fe(III) ions in the process of thermal phase separation of an alkali-borosilicate glass containing cobalt and ubiquitous trace iron

Debnath

1998

J. Mater. Res.

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Absorption spectra of added Co(II) ions and EPR spectra of both Co(II) and ubiquitous Fe(III) ions in an alkali-borosilicate glass of vycor-type composition are studied both before and after thermal phase separation of the glass as well as in a silica glass derived from the phase-separated glass through vycorization. The results show that although almost all Co(II) ions migrate to the separated alkali-borate phase at the time of phase separation, only the interstitial ions in the case of Fe(III) take part in similar migration. The Fe(III) ions in the substitutional silicon sites, however, remain unaffected. It is also revealed that as a consequence of the process of phase separation a small fraction of the interstitial Fe(III) ions gets converted into substitutional ions leading to a net increase in the concentration of substitutional Fe(III) ions in the glass. Analysis of both absorption and EPR spectra of the Co(II) ions suggests that a change of host of the ion due its migration does not bring about any significant change in its coordination structure, which is typically a distorted tetrahedron both in the parent glass as well as in the phase-separated borate glass.

show abstract

Irreversible spectral changes of cobalt(II) by moderate heating in sol-gel glasses, and their ligand field rationalization

Cited by 21 publications

References 27 publications

Modular Design of Advanced Catalytic Materials Using Hybrid Organic–Inorganic Raspberry Particles

Modular Design of Advanced Catalytic Materials Using Hybrid Organic–Inorganic Raspberry Particles

Optical and magnetic properties of cobalt(2+) ions in dried and heated silica gels prepared by the sol-gel process

A study on the migration of Co(II) and Fe(III) ions in the process of thermal phase separation of an alkali-borosilicate glass containing cobalt and ubiquitous trace iron

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