Crystal growth control of rod-shaped ε-Fe<sub>2</sub>O<sub>3</sub> nanocrystals

Tokoro, Hiroko; Fukui, Junpei; Watanabe, K.; Yoshikiyo, Marie; Namai, Asuka; Ohkoshi, Shin‐ichi

doi:10.1039/d0ra07256g

Cited by 6 publications

(3 citation statements)

References 37 publications

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“…The different AC susceptibility behavior of this sample may be due to a smaller grain size of both ε-Fe2O3 and hematite phases. Figure 3 illustrates the low-temperature remanence behavior and hysteresis loops measured at 295 K for two samples that show coercivities in excess of 1 Tesla, as expected for the ε-Fe2O3 phase [24,44,[46][47][48][49][50]. Coercivity, magnetization and remanence values are listed in Table 4.…”

Section: Magnetic Propertiesmentioning

confidence: 78%

Influence of the Preparation Technique on the Magnetic Characteristics of ε-Fe2O3-Based Composites

et al. 2022

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ε-Fe2O3 is an iron(III) oxide polymorph attracting an increasing interest due to its unique magnetic properties combining extremely high coercivity and relatively large saturation magnetization. We review existing methods for the ε-Fe2O3 synthesis focusing on synthesis speed, repeatability, manufacturability and purity of the final product. Samples of ε-Fe2O3 have been synthesized using the two methods that appear the most promising: silica gel impregnation and microemulsion. In both cases, ε-Fe2O3 and α-Fe2O3 are present in the final product as attested by X-ray diffraction patterns and magnetic properties (maximum coercive force at 300 K~1 Tesla). Two different precursors, iron(III) nitrate and iron(II) sulfate, have been used in the silica gel impregnation method. Somewhat surprisingly, iron sulfate proved superior yielding ε-Fe2O3 content of 69% in the total iron oxide product, compared to 25% for iron nitrate under the same synthesis conditions. These results pave the way for modifying the existing ε-Fe2O3 synthesis methods aiming to increase the content of the epsilon phase in the final product and, consequently, improve its physicochemical properties.

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Section: Magnetic Propertiesmentioning

confidence: 78%

Influence of the Preparation Technique on the Magnetic Characteristics of ε-Fe2O3-Based Composites

et al. 2022

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“…They exhibit large magnetic anisotropy and high-frequency millimeter-wave absorption. 18–45 Additionally, metal-substituted epsilon iron oxide, ε-M x Fe 2− x O 3 , 46–70 exhibits millimeter-wave absorption in the range of 35–222 GHz, in which the resonance frequency is controlled by a kind of substitution metal and substitution ratio. Recently, the resonance frequency shift due to change on the particle size of ε-Fe 2 O 3 nanomagnets has been also reported.…”

Section: Introductionmentioning

confidence: 99%

Particle size effect on millimeter-wave absorption, rotation, and ellipticity of gallium-substituted epsilon iron oxide

2022

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“…Among numerous iron oxide polymorphs, the most intriguing one is the metastable orthorhombic ε-Fe 2 O 3 phase, which does not exist in the bulk form. Epsilon ferrite is a ferrimagnet with a huge magnetocrystalline anisotropy that is responsible for the values of coercive force exceeding 2 T. Having attracted a lot of attention during the past few years [5][6][7], epsilon ferrite in the form of nanofilms [8][9][10] and nanoparticles [11][12][13][14] was shown to exhibit a complicated magnetic structure with four magnetic sub-lattices and room-temperature (RT) multiferroic behavior [15], which has not been observed in other simple metal oxides. Its large magnetic coercivity and proven magneto-electric coupling make this material ideal for the creation of novel oxide-based ferroic-on-semiconductor devices for spintronic applications, including low-power consumption magnetic media storage devices [16].…”

Section: Introductionmentioning

confidence: 99%

Technological Peculiarities of Epsilon Ferrite Epitaxial Stabilization by PLD

Dvortsova

2022

Surfaces

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The present paper describes the technological peculiarities relevant to the nucleation and further epitaxial growth of the metastable epsilon phase of iron oxide by means of pulsed laser deposition (PLD). The orthorhombic epsilon ferrite ε-Fe2O3 is an exotic member of a large family of iron oxide polymorphs, which attracts extensive attention nowadays due to its ultra-high magneto-crystalline anisotropy and room temperature multiferroic properties. Continuing the series of previous publications dedicated to the fabrication of ε-Fe2O3 films on GaN, this present work addresses a number of important requirements for the growing conditions of these films. Among the most sensitive technological parameters, the growth temperature must be high enough to aid the nucleation of the orthorhombic phase and, at the same time, low enough to prevent the thermal degradation of an overheated ε-Fe2O3/GaN interface. Overcoming the contradicting growth temperature requirements, an alternative substrate-independent technique to stabilize the orthorhombic phase by mild aluminum substitution is proposed. The advantages of this technique are demonstrated by the example of ε-Fe2O3 films PLD growth carried out on sapphire—the substrate that possesses a trigonal lattice structure and would normally drive the nucleation of the isostructural and energetically more favorable trigonal α-Fe2O3 phase. The real-time profiling of high-energy electron diffraction patterns has been extensively utilized throughout this work to keep track of the orthorhombic-to-trigonal balance being the most important feed-back parameter at the growth optimization stage.

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Crystal growth control of rod-shaped ε-Fe₂O₃ nanocrystals

Abstract: Crystal growth control of rod-shaped ε-Fe2O3 nanocrystals is achieved by a synthesis based on the sol–gel technique.

Cited by 6 publications

References 37 publications

Influence of the Preparation Technique on the Magnetic Characteristics of ε-Fe2O3-Based Composites

Influence of the Preparation Technique on the Magnetic Characteristics of ε-Fe2O3-Based Composites

Particle size effect on millimeter-wave absorption, rotation, and ellipticity of gallium-substituted epsilon iron oxide

Technological Peculiarities of Epsilon Ferrite Epitaxial Stabilization by PLD

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