Unravelling the Elusive Antiferromagnetic Order in Wurtzite and Zinc Blende CoO Polymorph Nanoparticles

Roca, Alejandro G.; Golosovsky, I. V.; Winkler, E.; López‐Ortega, Alberto; Estrader, Marta; Zysler, R.D.; Baró, María Dolors; Nogués, J.

doi:10.1002/smll.201703963

Cited by 16 publications

(28 citation statements)

References 106 publications

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“…The estimation from the XRD patterns using the Scherrer formula gives a characteristic average size for the ZB-CoO nanoparticles of 13.0(5) nm, in agreement with the TEM results [22].…”

Section: Zinc Blende Coo Nanoparticlessupporting

confidence: 85%

“…An early neutron diffraction study of CoO nanoparticles with wurtzite crystal structure showed the presence of a weak broad magnetic peak at low temperatures which was associated with a short-range magnetic order [3], in concordance with studies on hexagonal CoO thin films prepared by laser deposition [21]. However, recent neutron diffraction studies have established that both W-CoO and ZB-CoO are antiferromagnetic, although W-CoO exhibits a complex magnetic structure [22].…”

Section: Introductionsupporting

confidence: 60%

“…In neutron scattering the scattering lengths of oxygen and cobalt are comparable; therefore the profile refinement allows us to evaluate the relative occupancies of O and Co atoms. The refined values for zinc blende nanoparticles correspond to the chemical formula CoO 0.7 (1) , which indicates a strongly nonstoichiometric compound with a significant amount of oxygen vacancies [22].…”

Section: Zinc Blende Coo Nanoparticlesmentioning

confidence: 92%

“…The synthesis of nanostructured CoO with wurtzite and zinc blende phases was carried out by thermal decomposition of cobalt (II) acetylacetonate (Co(acac) 2 ) in 1-octadecene mediated by oleic acid [22]. 19.4 mmol Co(acac) 2 , 8.8 mmol oleic acid and 20 mL 1-octadecene were combined in a three-neck flask and degassed at room temperature for 30 min.…”

Section: Methodsmentioning

confidence: 99%

“…The XRD pattern shows the characteristic reflections from the W-CoO and ZB-CoO phases (Figure 5a). The refined unit cell parameters are a = 4.5534(1) Å for the cubic zinc blende crystal structure and a = 3.2526(1) Å; c = 5.1977(1) Å for the hexagonal wurtzite crystal structure [22]. The values in brackets correspond to the errors (i.e., estimated standard deviation).…”

Section: X-ray and Neutron Diffractionmentioning

confidence: 99%

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Zinc blende and wurtzite CoO polymorph nanoparticles: Rational synthesis and commensurate and incommensurate magnetic order

Golosovsky

Estrade

López‐Ortega

et al. 2019

Applied Materials Today

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On the nanoscale, CoO can have different polymorph crystal structures, zinc blende and wurtzite, apart from rock salt, which is the stable one in bulk. However, the magnetic structures of the zinc blende and wurtzite phases remain virtually unexplored. Here we discuss some of the main parameters controlling the growth of the CoO wurtzite and zinc blende polymorphs by thermal decomposition of cobalt (II) acetylacetonate. In addition we present a detailed neutron diffraction study of oxygen deficient CoO (CoO 0.70−0.75) nanoparticles with zinc blende (∼15 nm) and wurtzite (∼30 nm) crystal structures to unravel their magnetic order and its temperature evolution. The magnetic order of the zinc blende nanoparticles is antiferromagnetic and appears at the Néel temperature T N ∼ 203 K. It corresponds to the 3-rd type of magnetic ordering in a face-centered cubic lattice with magnetic moments aligned along a cube edge. The magnetic structure in the wurtzite nanoparticles turned out to be rather complex with two perpendicular components. One component is incommensurate, of the longitudinal spin wave type, with the magnetic moments confined in the ab-plane. In the perpendicular direction, this magnetic order is uncorrelated, forming quasi-two-dimensional magnetic layers. The component of the magnetic moment, aligned along the hexagonal axis, is commensurate and corresponds to the antiferromagnetic order known as the 2-nd type in a wurtzite structure. The Néel temperature of wurtzite phase is estimated to be ∼ 109 K. The temperature dependence of the magnetic reflections confirms the reduced dimensionality of the incommensurate magnetic order. Incommensurate magnetic structures in nanoparticles are an unusual phenomenon and in the case of wurtzite CoO it is probably caused by structural defects (e.g., vacancies, strains and stacking faults).

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“…The estimation from the XRD patterns using the Scherrer formula gives a characteristic average size for the ZB-CoO nanoparticles of 13.0(5) nm, in agreement with the TEM results [22].…”

Section: Zinc Blende Coo Nanoparticlessupporting

confidence: 85%

Section: Introductionsupporting

confidence: 60%

Section: Zinc Blende Coo Nanoparticlesmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: X-ray and Neutron Diffractionmentioning

confidence: 99%

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Zinc blende and wurtzite CoO polymorph nanoparticles: Rational synthesis and commensurate and incommensurate magnetic order

Golosovsky

Estrade

López‐Ortega

et al. 2019

Applied Materials Today

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Boosted N₂ Activation through 4f–2p–3d Orbital Hybridization for Efficient Nitrate Electrosynthesis

Wang

Chi

et al. 2023

Adv Funct Materials

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The electrochemical N2 oxidation reaction (NOR) has emerged as a promising approach for achieving high selectivity in nitric acid (HNO3) production. However, the sluggish N2 activation process in NOR due to the high cleavage energy barrier of the N≡N bond remains a challenge. Herein, a novel orbital hybridization strategy for tuning the NOR performance through the construction of cerium (Ce) 4f–O 2p–Co 3d network in Ce‐doped Co3O4 (Ce–Co3O4) is proposed. The Ce–Co3O4 catalyst exhibits an enhanced HNO3 yield of 24.76 µg h−1 mgcat−1 and a promoted Faradaic efficiency of 31.93% in 0.1 m Na2SO4 electrolyte under ambient conditions compared to those of the pure Co3O4 (13.75 µg h−1 mgcat−1 and 23.43%). Density functional theory caculations demonstrate the strong 4f–2p–3d orbital hybridization and electron transfer in Ce–Co3O4. Moreover, a series of in situ techniques provide direct evidence of stronger adsorption peaks for Co─N bond and the key intermediate *NO formed after N2 activation on the surface of Ce–Co3O4. This work provides a promising route for the preparation of efficient NOR catalysts and sheds light on the mechanism of N2 activation through orbital hybridization.

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The Effect of the Degree of Fluorination on the MOCVD Growth of Cobalt Oxide Thin Films using Co(II) Acetylacetonate Complexes

et al. 2021

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The structurally related cobalt β‐diketonate complexes Co(acac)2, Co(acac)2 ⋅ TMEDA, Co(tfac)2 ⋅ TMEDA, and Co(hfac)2 ⋅ TMEDA (acac=2,4‐pentanedionate, tfac=1,1,1‐trifluoro‐2,4‐pentane‐dionate, hfac=1,1,1,5,5,5‐hexafluoro‐2,4‐pentane‐dionate, TMEDA=N,N,N′,N′‐tetramethylethylenediamine) were thermochemically (thermogravimetric analysis, differential scanning calorimetry) and spectroscopically (infrared, UV‐VIS and electron resonance spectroscopy) characterised and used as precursor for the MOCVD growth of cobalt monoxide (CoO) thin films. The influence of the degree of fluorination of the cobalt precursors on the morphology (scanning electron microscopy) and phase composition (X‐ray diffraction) of the CoO films is demonstrated. Carbon, nitrogen and fluorine impurities as a result of the thermal decomposition of the 2,4‐pentanedionate and tetraamine ligands in the films were identified by X‐ray photoelectron spectroscopy, time‐of‐flight secondary ion mass spectrometry, Rutherford backscattering spectrometry and nuclear reaction analysis. In addition, the influence of these contaminants on the electrocatalytically activity for the oxygen evolution reaction (OER) in alkaline media of the MOCVD grown CoO films is shown.

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Unravelling the Elusive Antiferromagnetic Order in Wurtzite and Zinc Blende CoO Polymorph Nanoparticles

Cited by 16 publications

References 106 publications

Zinc blende and wurtzite CoO polymorph nanoparticles: Rational synthesis and commensurate and incommensurate magnetic order

Zinc blende and wurtzite CoO polymorph nanoparticles: Rational synthesis and commensurate and incommensurate magnetic order

Boosted N₂ Activation through 4f–2p–3d Orbital Hybridization for Efficient Nitrate Electrosynthesis

The Effect of the Degree of Fluorination on the MOCVD Growth of Cobalt Oxide Thin Films using Co(II) Acetylacetonate Complexes

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Unravelling the Elusive Antiferromagnetic Order in Wurtzite and Zinc Blende CoO Polymorph Nanoparticles

Cited by 16 publications

References 106 publications

Zinc blende and wurtzite CoO polymorph nanoparticles: Rational synthesis and commensurate and incommensurate magnetic order

Zinc blende and wurtzite CoO polymorph nanoparticles: Rational synthesis and commensurate and incommensurate magnetic order

Boosted N2 Activation through 4f–2p–3d Orbital Hybridization for Efficient Nitrate Electrosynthesis

The Effect of the Degree of Fluorination on the MOCVD Growth of Cobalt Oxide Thin Films using Co(II) Acetylacetonate Complexes

Contact Info

Product

Resources

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Boosted N₂ Activation through 4f–2p–3d Orbital Hybridization for Efficient Nitrate Electrosynthesis