Co2Z hexaferrite obtained by the citrate precursor method in an inert atmosphere

Caffarena, V.R.; Ogasawara, Tsuneharu; Capitaneo, Jefferson Leixas; Pinho, Catarina

doi:10.1590/s1517-70762008000200016

Cited by 7 publications

(7 citation statements)

References 7 publications

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“…Reportedly, Z-type hexaferrite contains both Y-and W-type hexaferrite phases [15][16][17]. However, the Y-type phase disappears after acid-etching, while the W-phase still exists as shown in Fig.…”

Section: Resultsmentioning

confidence: 95%

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

Lee

Hong

Park

et al. 2016

Journal of Magnetism and Magnetic Materials

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We report a low magnetic loss Ba 3 Co 2 Fe 24 O 41 (Co 2 Z) hexaferrite for use in gigahertz (GHz) antennas. Acid-etching was very effective in removal of unwanted Y-type hexaferrite (Ba 2 Co 2 Fe 12 O 22) from calcined Co 2 Z powder. It is found that the calcined and acid etched (AE) Co 2 Z hexaferrite shows a low magnetic loss tangent (tan δ μ) of 0.012 and 0.037 at 1 and 2 GHz, respectively. These low tan δ μ are attributed to removal of Y type hexaferrite, which possesses a lower anisotropy field (H k) than W-type hexaferrite (BaCo 2 Fe 16 O 27). The figure of merit (FOM) of the AE Co 2 Z hexaferrite is 141.7 and 48.7 at 1 and 2 GHz, respectively. These FOM are much higher than the FOM of previously reported low-loss magnetic materials. Therefore, the AE Co 2 Z hexaferrite can be a good candidate for GHz antenna application in the ultra-high frequency (UHF) band.

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Section: Resultsmentioning

confidence: 95%

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

Lee

Hong

Park

et al. 2016

Journal of Magnetism and Magnetic Materials

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“…In the absence of polyols during the synthesis, the formation of ZnAl 2 O 4 occurred solely through pathway 1, which involved the decomposition of the metallic citrate precursor complex. [ 31 ] In the synthesis method utilizing eg, apart from the formation pathway involving the metal citrate complex, an esterification process occurred to produce the polymeric citrate complex through pathway 2. Although both eg and pg200 were linear polyols, pg200 had a longer chain length.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Different Polyol Precursors on Disordered Spinel ZnAl₂O₄ Structure Prepared by the Polymeric Citrate Complex Method and the Corresponding Catalytic Behavior in the Glycerolysis of Urea

Pham-Ngoc,

Nguyen-Phu,

Lee

et al. 2023

Small Structures

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ZnAl2O4 is a cubic close‐packed oxide with tetrahedral and octahedral sites in the lattice structure. The catalytic activity of ZnAl2O4 is strongly connected with the surface properties caused by the partially inverse spinel ZnAl2O4 structure. In this research, ZnAl2O4 catalysts are prepared for the glycerolysis of urea via the polymeric citrate complex method using polymeric templates made of citric acid with a different polyol precursor. Depending on the polyol precursor, the partial inversion parameters representing the disordered bulk ZnAl2O4 structure are controlled, which results in different surface AlO4/AlO6 ratios and surface acidity. The specific surface areas of the prepared ZnAl2O4 catalysts are proportional to the molecular weight of the polyol precursor. The s–ZnAl2O4 (polyol precursor = sorbitol) prepared via two pathways from citrate complex and polymeric citrate complex shows the highest inversion parameter and surface acidity, leading to the highest glycerol carbonate (GC) yield and glycerol conversion in the glycerolysis of urea. A relationship between the GC yield and the surface properties, such as the acidity and inversion parameters, is established.

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“…It sounds this peak was related to the decomposition of remaining unreacted organic materials induced by excess citric acid and sulfate salt, The last exothermic peak at 600°C was associated with the decomposition of citrate that formed in gelation and crystallization of the CoAl 2 O 4 spinel at the same time. This pick was in accordance with a 20 wt% weight loss 27,28 …”

Section: Resultsmentioning

confidence: 99%

“…X‐ray diffraction and STA results were in accordance with previous researches which used citrate sol‐gel synthesis and nitrate as precursors. Based on these results, an organic chain of the metal‐organic compound was formed, and that leads to the conversion of the sol to a viscous gel which is cobalt aluminum polymer complex citrate 27‐29 …”

Section: Resultsmentioning

confidence: 99%

“…Caffarena et al suggested the following reactions for citrate sol‐gel synthesis that was used in this study. Based on this very study's precursor, it is expected that the final product in the gelling section will be cobalt aluminum complex in order of following reactions 27

{normalH}_{n} Cit = {normalH}_{n ‐ 1} {Cit}^{(4 ‐ n) ‐} + {normalH}^{+}

The citric acid structure has three carboxyl group and a hydroxyl group.…”

Section: Introductionmentioning

confidence: 99%

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A comparative study on citrate sol‐gel and combustion synthesis methods of CoAl₂O₄ spinel

Baseri

Naghizadeh

Rezaie

et al. 2020

Int J Applied Ceramic Tech

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Aluminates are chemicals made up of ceramic materials based on aluminum oxide as the main constituent. Aluminate materials are widely used in high-technology applications due to their unique properties, for instance, in magnetic materials, ceramic catalysis, absorbent materials, and so forth. 1-4 Spinel is a ceramic oxide with three elements which its general chemical formula is AB 2 O 4 where, in normal spinels, A stands for a bivalent metal cation (A 2+) which occupies a tetrahedral site and B represents a trivalent (B 3+) metal cation which occupies an octahedral site of a cubic lattice. In the same time, in inverse spinels, bivalent cation (A 2+) occupies an octahedral site and a trivalent (B 3+) cation occupies both octahedral and tetrahedral site. 4-6 Nowadays, cobalt aluminate (CoAl 2 O 4) are used as a color pigment in digital ceramic printing, cobalt and gibbsite precursor, catalyst, and color filter. 1-6 Moreover, this kind of spinel is one of the great interests among spinels due to its significant properties such as thermal and chemical stability, 6 optical host matrix, 4 high ability of cation diffusion, 4-7 catalytic application, to name but four. 8-10 Cobalt aluminate conventionally was synthesized by mixing alumina and cobalt oxide, and calcination of the mixture at ~1200°C for an extended period. This type of synthesis requires a long distance diffusion of metal ion that could lead to inhomogeneous and nonstoichiometry spinel. 3 Many novel synthesis methods, like combustion synthesis, 2,11-13 sol-gel, 14,15 low-temperature combustion synthesis (LCS), 3,16 reverse micelle processing, 5 polymeric precursors method, 4 etc. are used to solve these drawbacks. Combustion synthesis (CS) or Self-propagating high-temperature synthesis (SHS) is a potent, and low-cost technique for the synthesis of numerous industrially valuable materials and is used in the fabrication of several ceramic powders for

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Co2Z hexaferrite obtained by the citrate precursor method in an inert atmosphere

Cited by 7 publications

References 7 publications

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

The Effect of Different Polyol Precursors on Disordered Spinel ZnAl₂O₄ Structure Prepared by the Polymeric Citrate Complex Method and the Corresponding Catalytic Behavior in the Glycerolysis of Urea

A comparative study on citrate sol‐gel and combustion synthesis methods of CoAl₂O₄ spinel

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Co2Z hexaferrite obtained by the citrate precursor method in an inert atmosphere

Cited by 7 publications

References 7 publications

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

Low-loss Z-type hexaferrite (Ba3Co2Fe24O41) for GHz antenna applications

The Effect of Different Polyol Precursors on Disordered Spinel ZnAl2O4 Structure Prepared by the Polymeric Citrate Complex Method and the Corresponding Catalytic Behavior in the Glycerolysis of Urea

A comparative study on citrate sol‐gel and combustion synthesis methods of CoAl2O4 spinel

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Product

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The Effect of Different Polyol Precursors on Disordered Spinel ZnAl₂O₄ Structure Prepared by the Polymeric Citrate Complex Method and the Corresponding Catalytic Behavior in the Glycerolysis of Urea

A comparative study on citrate sol‐gel and combustion synthesis methods of CoAl₂O₄ spinel