Synthesis, microstructure and oxidation of Co-MgAl2O4 and Ni-MgAl2O4 nanocomposite powders

Quénard, Olivier; Billon, Laurent; Brieu, M.; Rousset, A.

doi:10.1016/0965-9773(96)00026-8

Cited by 26 publications

(30 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…30 This excess increases from C1 to C4, in relation with the increasing Co 2+ content in the starting solid solution (from 1 to 20 cat.%- Table 1). In comparison with the works of Ting and Lu, 32,33 the present specimens contain a relatively large excess of Al 2 O 3 , we use a slight higher pressure (43 MPa versus 38 MPa) and lower temperatures (900-1300 • C versus 1450 or 1550 • C).…”

Section: Influence Of the Content Of Carbon Nanotubesmentioning

confidence: 94%

“…X-ray diffraction revealed the presence of -Co besides the MgAl 2 O 4 matrix in all specimen and of some Mo 2 C in CM specimens. From the chemical composition of the starting catalytic materials, taking into account that the reduction of Co 2+ in Co 0 was complete, 30 we have deduced the volume contents in -Co and Mo 2 C (Table 3) and it is noted that the values are not higher than 3.08 and 2.47 vol.%, respectively. Calculations showed that the carbon contained in Mo 2 C is negligible when compared to that in the CNT.…”

Section: Influence Of the Content Of Carbon Nanotubesmentioning

confidence: 99%

See 1 more Smart Citation

Densification during hot-pressing of carbon nanotube–metal–magnesium aluminate spinel nanocomposites

Peigney

Rul

Lefevre-Schlick

et al. 2007

Journal of the European Ceramic Society

View full text Add to dashboard Cite

The densification by hot-pressing of ceramic-matrix composites containing a dispersion of carbon nanotubes (CNT), mostly single-walled, is studied for the first time. Fifteen different CNT-Co/Mo-MgAl 2 O 4 composite powders containing between 1.2 and 16.7 vol.% CNT were prepared by catalytic chemical vapour deposition. The in situ growth of CNT within the oxide powder made it possible to obtain a highly homogeneous distribution of CNT. Low contents of CNT (up to 5 vol.%) are beneficial for the first shrinkage step (up to 1100 • C), dominated by the rearrangement process, while higher contents are detrimental. At higher temperatures (1100-1300 • C), CNT clearly inhibit the shrinkage, and this detrimental effect regularly increases with the CNT content. Several explanations are proposed, in relation with the particular mechanical properties of CNT and their highly connected web-like distribution within the material.

show abstract

Section: Influence Of the Content Of Carbon Nanotubesmentioning

confidence: 94%

Section: Influence Of the Content Of Carbon Nanotubesmentioning

confidence: 99%

Densification during hot-pressing of carbon nanotube–metal–magnesium aluminate spinel nanocomposites

Peigney

Rul

Lefevre-Schlick

et al. 2007

Journal of the European Ceramic Society

View full text Add to dashboard Cite

show abstract

“…Other several methods have recently been used to prepare Ferrites in fine particle form, i.e. co-precipitation method and combustion in urea [2], mechanochemical activation [3] and rf plasma aerosol deposition technique [4].…”

Section: Introductionmentioning

confidence: 99%

Mössbauer spectroscopy study of aluminium substituted nickel-ferrites

2008

View full text Add to dashboard Cite

Powders of Al substituted Ni-ferrites (NiAl x Fe 2−x O 4 x = 0, 0.5, 1.0 and 1.5) were prepared using the calcination method. Mössbauer spectroscopy results of all samples show two well defined magnetic sextets corresponding to Fe 3+ ions in the A (tetrahedral) and B (octahedral) sites of the spinel structure. In addition, a quadrupole doublet with quadrupole splitting of (∼0.53 mm/s) starts evolving upon Al substitution. This doublet is associated with a new Fe-Al-oxide phase. The X-ray diffraction patterns show, in addition to the original peaks, new peaks evolve and increase in intensity as the Al concentration increases, confirming the evolution of this new phase.

show abstract

“…In earlier works, we have shown that oxide solid solutions prepared by decomposition and calcination of oxalate mixtures or by nitrate/urea combustion are also potentially high-performance precursors because the as-such produced materials feature a very homogeneous distribution of the desired metallic ions in their structures. Using the appropriate temperature and duration in the reduction process of these precursors, one is able to precisely control the micro/nanostructure of Fe/Cr-Al 2 O 3 [15][16][17][18][19], Fe/CrCr 2 O 3 [20], Fe/Co/Ni-MgO [21,22] and Fe/Co/Ni-MgAl 2 O 4 [23][24][25] nanocomposite powders. Although Ni-Y 2 O 3 -ZrO 2 composites are claimed to be materials of greater importance for solid-oxide fuel cells [26], Fe-ZrO 2 ceramic-matrix micro-or nanocomposites have been seldom studied.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Fe-ZrO2 nanocomposite powders by reduction in H2 of a nanocrystalline (Zr, Fe)O2 solid solution

Resende

García

Peigney

et al. 2009

Journal of Alloys and Compounds

Self Cite

View full text Add to dashboard Cite

a b s t r a c tThe formation of Fe-ZrO 2 nanocomposite powders by reduction in hydrogen of a nanocrystalline totally stabilized Zr 0.9 Fe 0.1 O 1.95 solid solution was investigated by X-ray diffraction (XRD), field-emission-gun scanning electron microscopy (FEG-SEM) and Mössbauer spectroscopy. The reduction of the stabilized Zr 0.9 Fe 0.1 O 1.95 solid solution and the formation of metallic particles precedes the transformation of zirconia into the monoclinic phase, which becomes the major zirconia phase upon reduction at 950 • C. ␣-Fe particles with a size distribution slightly increasing from 10-50 to 20-70 nm upon the increase in reduction temperature are observed and a second population of smaller (<5 nm) ␥-Fe nanoparticles is also noticed when the reduction is performed at 1000 • C. Another metallic phase with a hyperfine field of ∼200 kOe at RT (∼250 kOe at 80 K) is detected, which could account for an Fe/Zr phase. It could be formed by the reduction on an Fe 2+ -rich transient phase incorporating a small fraction of the Zr 4+ ions, formed by a phase partitioning process superimposed to the reduciton processes.

show abstract

Synthesis, microstructure and oxidation of Co-MgAl2O4 and Ni-MgAl2O4 nanocomposite powders

Cited by 26 publications

References 16 publications

Densification during hot-pressing of carbon nanotube–metal–magnesium aluminate spinel nanocomposites

Densification during hot-pressing of carbon nanotube–metal–magnesium aluminate spinel nanocomposites

Mössbauer spectroscopy study of aluminium substituted nickel-ferrites

Synthesis of Fe-ZrO2 nanocomposite powders by reduction in H2 of a nanocrystalline (Zr, Fe)O2 solid solution

Contact Info

Product

Resources

About