Mössbauer and infrared spectroscopic studies of novel mixed valence states in cobaltous ferrocyanides and ferricyanides

Reguera, E.; Bertrán, JF; Díaz, C.; Blanco, José Miguel Arias; Rondon, Sonia

doi:10.1007/bf02101072

Cited by 45 publications

(32 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fig. 8 shows the 57Fe Mössbauer spectra [52][53][54] of the Fe-CN-Co MCNPs prepared at 0 and 12 h. The spectra were measured at 300 and 15 K in the cooling mode. We assume that the crystal structure of Fe-CN-Co MCNPs is stable during the measurement independent of temperature because of the lack of the main driving force for the structural change (here CTA).…”

Section: Magnetic Properties Of Fe-cn-co Mcnpsmentioning

confidence: 99%

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Yamada

Sato

Miyake

et al. 2007

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Section: Magnetic Properties Of Fe-cn-co Mcnpsmentioning

confidence: 99%

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Yamada

Sato

Miyake

et al. 2007

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

“…In the as-grown film ͓͑a͒ ␦ = 0.00͔, an intense absorption band is observed at 2080 cm −1 , which is ascribed to the stretching vibration mode of the CN moiety in the ͓Fe II ͑CN͒ 6 ͔ complex. 18 The intensity of the 2080 cm −1 band decreases with the increase in ␦. Accordingly, a new absorption band appears at 2160 cm −1 , which is ascribed to the CN stretching mode of the ͓Fe III ͑CN͒ 6 ͔ complex.…”

Section: A Valence Control By An Electrochemical Methodsmentioning

confidence: 96%

“…Accordingly, a new absorption band appears at 2160 cm −1 , which is ascribed to the CN stretching mode of the ͓Fe III ͑CN͒ 6 ͔ complex. 18 In Fig. 3, we plotted the oscillator strength f for both the absorption bands against ␦.…”

Section: A Valence Control By An Electrochemical Methodsmentioning

confidence: 99%

Electronic phase diagram of valence-controlled cyanide:Na0.84−δCo[Fe(CN)
Nakada
¹
,
Kamioka
²
,
Moritomo
³

et al. 2008
Phys. Rev. B
41
0
44
0
View full text Add to dashboard Cite

Electronic phase diagram has been derived for the Prussian-Blue-type cyano-bridged transition-metal compound, Na 0.84−␦ Co͓Fe͑CN͒ 6 ͔ 0.71 · 3.8H 2 O ͑0.0Յ ␦ Յ 0.61͒, as a function of the hole concentration ␦ of the d-electron system. The mother compound ͑␦ =0͒ takes the Co 2+ ͑t 2g 5 e g 2 : S =3/ 2͒ and Fe 2+ ͑t 2g 6 : S =0͒ configuration and is paramagnetic down to zero temperature. At room temperature, the holes are selectively introduced on the Fe site. A slight hole doping ͑␦ = 0.13͒ causes the charge-transfer ͑CT͒ transition, that is, cooperative electron transfer from the Co 2+ site to the Fe 3+ site, with a decrease in temperature below T CT Ϸ 250 K. With a further increase in ␦, T CT slightly decreases from Ϸ230 K at ␦ = 0.24 to ϳ210 K at ␦ = 0.61. Accordingly, the nature of the transition changes from the second-order type to the first-order type. In all the concentration ranges, the high-temperature ͑HT͒ phase is metastable even at low temperature. In this metastable phase, the Fe 3+ ͑t 2g 5 : S =1/ 2͒ species mediate the ferromagnetic exchange coupling between the adjacent Co 2+ spins. The ferromagnetic transition appears at ␦ = 0.39, and the transition temperature T C increase from 7 K at ␦ = 0.39 to 13 K at ␦ = 0.61. Based on these experimental data, we will discuss the significant roles of the coupling between the charge, spin, and lattice degrees of freedom in the transition-metal cyanides.

show abstract

“…A few decades ago, Reguera et al demonstrated that oxidation states of open metal sites in some porous cyanometallates can be modified through a reaction with ozone [33][34][35][36]. These reactions were conducted without dehydrating the material, and therefore, the water molecules were involved in the reaction.…”

Section: Introductionmentioning

confidence: 99%

Structural and Gas Retention Changes Induced by Ozonization of Cobalt(II) and Manganese(II) Hexacyanocobaltates(III)

et al. 2017

View full text Add to dashboard Cite

Transition metal hexacyanocobaltates are porous materials with open metal sites and a wide variety of pores. In this work, manganese(II) and cobalt(II) hexacyanocobaltates(III) have been selected to explore the interactions between the open metal sites located in their pores and the guest molecules: hydrogen, carbon dioxide, water and methanol. An experimental setup was designed and implemented to conduct post-synthesis modification of the solids with ozone. Samples were dehydrated, ozonized and saturated with methanol in situ. Ozone molecules acted on the open metal sites changing their oxidation state, causing a contraction of the unit cell and inducing a stronger interaction of the molecules of water and methanol with the lattice. This strengthening prevented the lattice from being evacuated without compromising its framework stability. The decomposition temperature decreased in all ozonized samples as a consequence of the elongation and weakening of the cobalt-carbon bond. Active infrared and Raman bands were used to monitor the interaction between the open metal sites at the framework surface and the guest molecules. The cell contraction and the presence of residual methanol molecules in the porosity reduced the hydrogen and carbon dioxide retention capacity of the samples.

show abstract

Mössbauer and infrared spectroscopic studies of novel mixed valence states in cobaltous ferrocyanides and ferricyanides

Cited by 45 publications

References 3 publications

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Electronic phase diagram of valence-controlled cyanide:Na0.84−δCo[Fe(CN)
Nakada
¹
,
Kamioka
²
,
Moritomo
³

et al. 2008
Phys. Rev. B
41
0
44
0
View full text Add to dashboard Cite

Structural and Gas Retention Changes Induced by Ozonization of Cobalt(II) and Manganese(II) Hexacyanocobaltates(III)

Contact Info

Product

Resources

About

Mössbauer and infrared spectroscopic studies of novel mixed valence states in cobaltous ferrocyanides and ferricyanides

Cited by 45 publications

References 3 publications

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Electronic phase diagram of valence-controlled cyanide:Na0.84−δCo[Fe(CN)Nakada1, Kamioka2, Moritomo3 et al. 2008Phys. Rev. B410440View full textAdd to dashboardCite

Structural and Gas Retention Changes Induced by Ozonization of Cobalt(II) and Manganese(II) Hexacyanocobaltates(III)

Contact Info

Product

Resources

About

Electronic phase diagram of valence-controlled cyanide:Na0.84−δCo[Fe(CN)
Nakada
¹
,
Kamioka
²
,
Moritomo
³

et al. 2008
Phys. Rev. B
41
0
44
0
View full text Add to dashboard Cite