Synthesis and Characterization of Hydrotalcites Containing Ni(II) and Fe(III) and Their Calcination Products

Arco, M. Del; Malet, P.; Trujillano, Raquel; Rives, V.

doi:10.1021/cm9804923

Cited by 129 publications

(54 citation statements)

References 42 publications

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“…Several experimental studies on topotactic structural evolution in the thermald ecompositiono fL DHs have been performed; [16,21] these show that the decomposition process involvesf our main stages:the first step corresponds to the evaporation of weakly adsorbed surface and interlayer water,t he second one is due to the removal of intercalated anions, the third one involves the dehydroxylation and collapse of the layered structure, and the final step is usuallya ttributed to the formation of mixed-metal oxides( MMOs). [19,22,23] Petrov and Markov proposed "similar crystallographic correlations"b etween LDHs and the as-obtained metal oxidest od efine the topotactic decomposition of LDHs, and believed thatm etal distribution in the crystal lattice was ak ey issue in understanding the topotactic process. [16] Recently,s ome researchers deduced that the stacking of cationss howed the largestd ensity (compared with other facets) on the (00l)p lane of LDH;t herefore, during the topotactic decomposition of LDHs, oxide nucleationo nt he (00l)f acet gave the lowest nucleation energy and led to the formation of the (111)-oriented metal oxides.…”

Section: Introductionmentioning

confidence: 99%

DFT‐Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides

et al. 2016

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The thermal topotactic transformation mechanism of MgAl layered double hydroxides (LDHs) is investigated by a combined theoretical and experimental study. Thermogravimetric differential thermal analysis (TG-DTA) results reveal that the LDH phase undergoes four key endothermic events at 230, 330, 450, and 800 °C. DFT calculations show that the LDH decomposes into CO2 and residual O atoms via a monodentate intermediate at 330 °C. At 450 °C, the metal cations almost maintain their original distribution within the LDH(001) facet during the thermal dehydration process, but migrate substantially along the c-axis direction perpendicular to the (001) facet; this indicates that the metal arrangement/dispersion in the LDH matrix is maintained two-dimensionally. A complete collapse of the layered structure occurs at 800 °C, which results in a totally disordered cation distribution and many holes in the final product. The structures of the simulated intermediates are highly consistent with the observed in situ powder XRD data for the MgAl LDH sample calcined at the corresponding temperatures. Understanding the structural topotactic transformation process of LDHs would provide helpful information for the design and preparation of metal/metal oxides functional materials derived from LDH precursors.

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Section: Introductionmentioning

confidence: 99%

DFT‐Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides

et al. 2016

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“…As layered hosts, LDHs have been used in many potential applications, such as catalysts, ceramic precursors, ion exchangers, absorbents, medicine stabilizers, and for controlled release of anions [6][7][8][9][10][11][12][13]. Very recently, their potential as nanofillers for preparing polymer nanocomposites has received considerable attention from both academic and industrial points of view.…”

Section: Introductionmentioning

confidence: 99%

Effect of surfactant alkyl chain length on the dispersion, and thermal and dynamic mechanical properties of LDPE/organo-LDH composites

Muksing¹,

Magaraphan²,

Coiai³

et al. 2011

Express Polym. Lett.

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Abstract. Low density polyethylene/layered double hydroxide (LDH) composites were prepared via melt compounding using different kinds of organo-LDHs and polyethylene-grafted maleic anhydride as the compatibilizer. The organo-LDHs were successfully prepared by converting a commercial MgAl-carbonate LDH into a MgAl-nitrate LDH, which was later modified by anion exchange with linear and branched sodium alkyl sulfates having different alkyl chain lengths (n c = 6, 12 and 20). It was observed that, depending on the size of the surfactant alkyl chain, different degrees of polymer chain intercalation were achieved, which is a function of the interlayer distance of the organo-LDHs, of the packing level of the alkyl chains, and of the different interaction levels between the surfactant and the polymer chains. In particular, when the number of carbon atoms of the surfactant alkyl chain is larger than 12, the intercalation of polymer chains in the interlayer space and depression of the formation of large aggregates of organo-LDH platelets are favored. A remarkable improvement of the thermal-oxidative degradation was evidenced for all of the composites; whereas only a slight increase of the crystallization temperature and no significant changes of both melting temperature and degree of crystallinity were achieved. By thermodynamic mechanical analysis, it was evidenced that a softening of the matrix is may be due to the plasticizing effect of the surfactant.

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“…level [19], and the mechanism of the transformation from the LDH precursor to the final composites has been investigated in detail [20][21][22]. The structure of the LDH precursor belongs to the hexagonal group, and the cations on the (00l) facets are arranged in an ordered "hexagon" formation.…”

Section: Introductionmentioning

confidence: 99%

Exchange-biased NiFe2O4/NiO nanocomposites derived from NiFe-layered double hydroxides as a single precursor

Zhao

Wang

et al. 2010

Nano Res.

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NiFe 2 O 4 nanoparticles (<10 nm) embedded in a NiO matrix have been fabricated by calcining the corresponding Ni Ⅱ Fe Ⅲ -layered double hydroxide (LDH) precursors at high temperature (500 °C ). Compared with the NiFe 2 O 4 /NiO nanocomposite obtained by calcination of a precursor prepared by a traditional chemical coprecipitation method, those derived from NiFe-LDH precursors show much higher blocking temperatures (T B ) (~380 K). The enhanced magnetic stability can be ascribed to the much stronger interfacial interaction between NiFe 2 O 4 and NiO phases due to the topotactic nature of the transformation of the LDH precursor to the NiFe 2 O 4 /NiO composite material. Through tuning the Ni Ⅱ /Fe Ⅲ molar ratio of the NiFe-LDH precursor, the NiFe 2 O 4 concentration can be precisely controlled, and the T B value as well as the magnetic properties of the final material can also be regulated. This work represents a successful example of the fabrication of ferro(ferri)magnetic (FM)/antiferrimagnetic (AFM) systems with high magnetic stability from LDH precursors. This method is general and may be readily extended to other FM/AFM systems due to the wide range of available LDH precursors.

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Synthesis and Characterization of Hydrotalcites Containing Ni(II) and Fe(III) and Their Calcination Products

Cited by 129 publications

References 42 publications

DFT‐Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides

DFT‐Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides

Effect of surfactant alkyl chain length on the dispersion, and thermal and dynamic mechanical properties of LDPE/organo-LDH composites

Exchange-biased NiFe2O4/NiO nanocomposites derived from NiFe-layered double hydroxides as a single precursor

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