Thermodynamic properties of Co(OH)2 from hydrothermal equilibria in cobalt oxide systems

Basavalingu, B.; Tareen, J. A. K.; Bhandage, G. T.

doi:10.1007/bf01729373

Cited by 13 publications

(7 citation statements)

References 4 publications

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“…The appearance of two strong bands at 660 and 570 cm À1 due to the n (Co-O) mode is a clear evidence for the presence of the crystalline CoO, where Co 3 O 4 bands appeared at 670 and 580 cm À1 as confirmed with [8]. In general, the as-deposited films converted to Co 3 O 4 , upon heating in vacuum at 350-400 C accompanied by a color change to dark brown/ black [13]. The decomposition of Co 3 O 4 to CoO in air was found to take place above 800 C [14,15].…”

Section: Investigationsmentioning

confidence: 68%

Preparation of oriented CoO(001) films on MgO(001) by sol–gel two-steps method

Selim¹

2004

Journal of Crystal Growth

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Section: Investigationsmentioning

confidence: 68%

Preparation of oriented CoO(001) films on MgO(001) by sol–gel two-steps method

Selim¹

2004

Journal of Crystal Growth

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“…After the cone experiment, the material did not match CoO as in other PMMA-LDH samples, but a less crystalline phase, close to both CoAl 2 O 4 and Co 2 AlO 4 was observed. Due to the poor crystallinity of this phase, we can not rule out the presence of Co 3 O 4 , a phase that is more stable than CoO in the presence of oxygen below 1000 C. 45 Ulibarri et al reported that a hydrotalcite-like compound (CoAl-CO 3 LDH) with oxidizable cations shows an exothermic effect at 568 K in the DTA patterns which are associated with a Co (II) / Co(III) oxidation process, since this event was not observed when the analysis was carried out in nitrogen. 42 When calcined at 1000 C, the peaks obtained for their samples were matched with Co 3 O 4 , CoAl 2 O 4 and/or Co 2 AlO 4 .…”

Section: Fire Properties Of Pmma-ldh Systemsmentioning

confidence: 96%

“…Due to the poor crystallinity of this phase, we cannot rule out the presence of Co3O4, a phase that is more stable than CoO in the presence of oxygen below 1000 °C. 45 Ulibarri et al reported that a hydrotalcite-like compound (CoAl-CO3 permission has been granted for this version to appear in e-Publications@Marquette. Royal Society of Chmistry does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Royal Society of Chmistry.…”

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confidence: 99%

Aluminum-containing layered double hydroxides: the thermal, mechanical, and fire properties of (nano)composites of poly(methyl methacrylate)

et al. 2008

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Hydrotalcite-like anionic clays or layered double hydroxides (LDHs IntroductionIn recent years, polymer-inorganic nanocomposites have been the subject of extensive research. Previous studies on the layered materials have mainly focused on the layered silicates and polymerlayered silicate nanocomposites, 1 because of the relatively low layer charge density and the easy exfoliation of montmorillonite (MMT)-type layered silicate compounds. Anionic clays are also of interest as they may have properties that are parallel to or divergent from those of the cationic clays. The most well-known anionic clays are the hydrotalcitelike layered double hydroxides or LDHs. 2 LDHs have a much higher charge density than MMT in the interlayer and a stronger interaction among the hydroxide sheets than layered silicates, which makes the exfoliation of LDHs much more difficult. 3 Recently, a number of reports on the exfoliation of LDHs 4 and NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Chemistry, Vol. 18, No. 26 (2008): pg. 3091-3102. DOI. This article is © Royal Society of Chmistry and permission has been granted for this version to appear in e-Publications@Marquette. Royal Society of Chmistry does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Royal Society of Chmistry. Journal of Materials3 polymer-LDH exfoliated nanocomposites 5 have been published. These synthetic anionic clays are emerging as potential fire retardants. 6 Layered double hydroxides consist of positively charged metal hydroxides sheets with anions (along with water) located between the layers to compensate the charge on the layers. 7 The LDH structure is described with the ideal formula [ , and various carboxylates, etc.; intra and inter denote the intralayer domain and the interlayer space, respectively. The LDH structure consists of brucite-like layers constituted of edge-sharing M(OH)6 octahedra. 8 Partial M III for M II substitution induces a positive charge on the layers, balanced by the presence of the interlayer anions. LDHs then consist of a stacking of positively charged layers with anions intercalated in the interlayer region, usually referred to as the gallery space, together with water molecules. LDHs exhibit anion-exchange properties 9 and their interlayer spacing can change depending on the size of the intercalated anions. 10 When heated above about 600 °C, these materials lead to mixed oxides. 11The presence of an organic moiety in the LDH gallery space plays an important role in the preparation of the LDH-polymer nanocomposites. Pinnavaia et al.12 reported a Mg 2+ /Al 3+ /Cl -LDH with a gallery height of approximately 2.97 Å. The size of the interlayer space was calculated from a basal spacing of 7.74 Å (indicated by X-ray powder diffraction) and the thickness of the brucite layer (4.77 Å). The gallery distance between each ...

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“…Their number and nature depend on the cations involved in the structure and on the temperature. However, some general tendencies can be expected, considering that below 1100 K, Ni and Mg probably form mixed oxides of NiO and MgO type on the one hand, [9,11,12] while, on the other hand, Co easily forms spinel-like structures. [7,8] The results from TG experiments prompted us to study the samples calcined at 573 and 773 K, since the main structural transformations of LDHs occur in this temperature range.…”

Section: Calcination Of the Ldh Precursorsmentioning

confidence: 99%

Characterization of Calcined and Reduced Multi-Component Co−Ni−Mg−Al-Layered Double Hydroxides

Tichit

Ribet

Coq

2001

Eur. J. Inorg. Chem.

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Several Co−Ni−Mg−Al‐layered double hydroxides (LDH) have been synthesized by coprecipitation at constant pH = 9. All samples present well crystallized, layered structures, no excess phases were detected by X‐ray diffraction, and the lattice a parameter followed the Vegard correlation. The cations thus belong to the same, brucite‐like, lattice. Calcined samples exhibit XRD patterns of the crystallographic phase preferentially adopted by the major cation in the LDH: i.e., a mixed oxide of the rock salt type in the case of Ni or Mg, and a spinel‐like structure for Co. Surface areas reached maximum values in the range of 200−300 m2g−1 after calcination at 573 K. They were stabilized with increasing Ni or Mg content, as higher amounts of mixed oxide phase were formed. Programmed temperature reduction showed two domains of H2 consumption, assigned to reduction of Co3−xNixO4 species below 720 K, and to NiMg(Al)O and Co3−x−yNixMgyAlO6, of rock salt type and spinel‐like structures respectively, above this temperature. These assignments are in agreement with the XRD patterns and show that Ni and Co are associated in the same crystallographic phases.

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Thermodynamic properties of Co(OH)2 from hydrothermal equilibria in cobalt oxide systems

Cited by 13 publications

References 4 publications

Preparation of oriented CoO(001) films on MgO(001) by sol–gel two-steps method

Preparation of oriented CoO(001) films on MgO(001) by sol–gel two-steps method

Aluminum-containing layered double hydroxides: the thermal, mechanical, and fire properties of (nano)composites of poly(methyl methacrylate)

Characterization of Calcined and Reduced Multi-Component Co−Ni−Mg−Al-Layered Double Hydroxides

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