Severe reduction of Ni–Zn ferrites during consolidation by Spark Plasma Sintering (SPS)

Valenzuela, R.; Gaudisson, Thomas; Ammar, Souad

doi:10.1016/j.jmmm.2015.07.044

Cited by 19 publications

(8 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is also exploited to stabilize the magnetization of the soft F reference layer in giant magnetoresistance (GMR)-based computer read heads 5–7 . Similarly, it is employed in commercial magnetic random access memory (MRAM) circuits 8,9 and is being investigated for the design of rare-earth free permanent magnets 10 .…”

Section: Introductionmentioning

confidence: 99%

On the limits of Reactive-Spark-Plasma Sintering to prepare magnetically enhanced nanostructured ceramics: the case of the CoFe2O4-NiO system

Franceschin

Gaudisson

Menguy

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

Magnetic materials are crucial for the efficiency of the conversion-storage-transport-reconversion energy chain, and the enhancement of their performance has an important impact on technological development. The present work explores the possibility of preparing hetero-nano-structured ceramics based on magnetic oxides, by coupling a ferrimagnetic phase (F) with an antiferromagnetic one (AF) on the nanometric scale. The field-assisted sintering technique or SPS (Spark-Plasma Sintering), adopted at this purpose, ensures the preservation of nano-sized crystals within the final solid structure. The aim is to establish how exchange bias may affect the resulting nano-consolidates and to investigate the potential of this process to increase the total magnetic anisotropy of the CoFe2O4 grains, and thus their coercive field, while keeping the saturation magnetization the same. The structure, microstructure and magnetic properties of the ceramics obtained were studied by several techniques. The results show that the sintering process, along with its typical reductive atmosphere, modifies the composition of the constituents. A new metallic phase appears as a consequence of the reciprocal diffusion of Co and Ni cations, leading to a change in the amount and structure of the AF phase. We propose a schematic representation of the atomic movements that hinder an exchange bias effect between the F and AF phases.

show abstract

Section: Introductionmentioning

confidence: 99%

On the limits of Reactive-Spark-Plasma Sintering to prepare magnetically enhanced nanostructured ceramics: the case of the CoFe2O4-NiO system

Franceschin

Gaudisson

Menguy

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…In certain cases also a colour gradient in the axial direction was observed, which was thought to be the consequence of gradient in stoichiometry resulting from the axial gradient in temperature due to the non-perfect centring of the sample in the tools. Valenzuela et al 17. reported the partial reduction of Fe 3+ to Fe 2+ during SPS of NiZn ferrites of composition Zn 0.7 Ni 0.3 Fe 2 O 4 .…”

mentioning

confidence: 99%

On the Role of the Electrical Field in Spark Plasma Sintering of UO2+x

Tyrpekl

Naji

Holzhäuser

et al. 2017

Sci Rep

View full text Add to dashboard Cite

The electric field has a large effect on the stoichiometry and grain growth of UO2+x during Spark Plasma Sintering. UO2+x is gradually reduced to UO2.00 as a function of sintering temperature and time. A gradient in the oxidation state within the pellets is observed in intermediate conditions. The shape of the gradient depends unequivocally on the direction of the electrical field. The positive surface of the pellet shows a higher oxidation state compared to the negative one. An area with larger grain size is found close to the positive electrode, but not in contact with it. We interpret these findings with the redistribution of defects under an electric field, which affect the stoichiometry of UO2+x and thus the cation diffusivity. The results bear implications for understanding the electric field assisted sintering of UO2 and non-stoichiometric oxides in general.

show abstract

“…In the case of ferromagnetic p-doped manganite ceramics, the formed oxygen vacancies decrease the average oxidation state of the paramagnetic manganese cations, inducing a net reduction of the Curie temperature of the final solid in comparison to its conventionally made bulk counterpart [22]. In Ni-Zn ferrite, a well-known resistive soft magnet, consolidation by SPS involves a Fe 3+ into Fe 2+ reduction inside the ferrite grains compensated by a loss of Ni cations, which precipitate as Ni metal between the grains, increasing the total electrical conductivity [23].…”

Section: Reduction Reactions During Sps Processesmentioning

confidence: 99%

Sintering and Reactive Sintering by Spark Plasma Sintering (SPS)

Franceschin¹,

Flores‐Martínez²,

Vázquez‐Victorio³

et al. 2018

Sintering of Functional Materials

Self Cite

View full text Add to dashboard Cite

A wide variety of technological applications, especially in electronics, requires high-density nanostructured solids, consolidated by sintering from nanoparticles. A new sintering technique known as spark plasma sintering (SPS) appears as the only method to reach high densities while preserving the final grain size within the nanometric range, with the added advantage of carrying out the process at significantly lower temperatures and shorter times as compared with the classical processes. Recent studies have revealed that in many cases, SPS can also accomplish the solid-state reaction to achieve the desired compound, leading to reactive SPS (RSPS). In this chapter, a review of RSPS is presented, focusing particularly on magnetic oxide materials as functional solids.

show abstract

Severe reduction of Ni–Zn ferrites during consolidation by Spark Plasma Sintering (SPS)

Cited by 19 publications

References 12 publications

On the limits of Reactive-Spark-Plasma Sintering to prepare magnetically enhanced nanostructured ceramics: the case of the CoFe2O4-NiO system

On the limits of Reactive-Spark-Plasma Sintering to prepare magnetically enhanced nanostructured ceramics: the case of the CoFe2O4-NiO system

On the Role of the Electrical Field in Spark Plasma Sintering of UO2+x

Sintering and Reactive Sintering by Spark Plasma Sintering (SPS)

Contact Info

Product

Resources

About