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13 pages, 3096 KiB

Open AccessArticle

X-ray Absorption Spectroscopy Study of Iron Site Manganese Substituted Yttrium Orthoferrite

by Turghunjan Gholam and Hui-Qiong Wang

Molecules 2022, 27(21), 7648; https://doi.org/10.3390/molecules27217648 - 7 Nov 2022

Viewed by 3366

In this work, manganese (Mn)-doped YFeO₃, i.e., YFM_xO powders with 0 ≤ x ≤ 0.1, was synthesized by a hydrothermal method to study the influences of doping on its structural, morphological, optical, magnetic, and local electrical properties. The experimental results show that all the samples exhibit an orthorhombic structure with space group Pnma. Refined structure parameters are presented. Morphology images show the shape evolution from layered to multilayered with increasing Mn content. Infrared spectra reveal the characteristic vibrations of the obtained YFM_xO samples. From the magnetic study, an increased magnetic moment in the range of 0 ≤ x ≤ 0.075 is observed. The Fe and Y K-edge local structure studies indicate that the valency of Fe and Y is mainly found in the trivalent state, which also indicates that the substitution of Mn ions not only affects the nearest neighbor atomic shell of Fe but also affects the nearest neighbor’s local structure of Y atoms. Our results show that the addition of Mn exhibits an evident influence on the local structural and magnetic properties. Full article

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12 pages, 2548 KiB

Open AccessArticle

Mössbauer Synchrotron and X-ray Studies of Ultrathin YFeO₃ Films

by Marina Andreeva, Roman Baulin, Aleksandr Nosov, Igor Gribov, Vladimir Izyurov, Oleg Kondratev, Ilia Subbotin and Elkhan Pashaev

Magnetism 2022, 2(4), 328-339; https://doi.org/10.3390/magnetism2040023 - 29 Sep 2022

Cited by 10 | Viewed by 2751

Abstract

The YFeO₃ orthoferrite is one of the most promising materials for antiferromagnetic (AFM) spintronics. Most studies have dealt with bulk samples, while the thin YFeO₃ films possess unusual and variable properties. Ultrathin (3–50 nm) YFeO₃ films have been prepared by [...] Read more.

1 \bar{1} 0 2

)-oriented Al₂O₃ substrates (r-Al₂O₃). Their characterization was undertaken by the Mössbauer reflectivity method using a Synchrotron Mössbauer Source and by X-ray diffraction (XRD) including grazing incidence diffraction (GI-XRD). For thin films with different thicknesses, the spin reorientation was detected under the application of the magnetic field of up to 3.5 T. Structural investigations revealed a predominant orthorhombic highly textured YFeO₃ phase with (00l) orientation for relatively thick (>10 nm) films. Some inclusions of the Y₃Fe₅O₁₂ garnet (YIG) phase as well as a small amount of the hexagonal YFeO₃ phase were detected in the Mössbauer reflectivity spectra and by XRD. Full article

(This article belongs to the Special Issue Magnetic Low-Dimensional Structures and Hybrid Materials)

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11 pages, 620 KiB

Open AccessArticle

Multiferroic, Phonon and Optical Properties of Pure and Ion-Doped YFeO₃ Nanoparticles

by Angel Apostolov, Iliana Apostolova and Julia Wesselinowa

Nanomaterials 2021, 11(10), 2731; https://doi.org/10.3390/nano11102731 - 15 Oct 2021

Cited by 20 | Viewed by 2120

Abstract

The magnetic, electric, phonon and optical properties of pure and ion-doped orthorhombic YFeO

_{3}

nanoparticles are studied for the first time theoretically. The spontaneous magnetization

M_{s}

in YFeO

_{3}

decreases with decreasing particle size.

M_{s}

is also shape dependent. The magnetization [...] Read more.

The magnetic, electric, phonon and optical properties of pure and ion-doped orthorhombic YFeO

_{3}

nanoparticles are studied for the first time theoretically. The spontaneous magnetization

M_{s}

in YFeO

_{3}

decreases with decreasing particle size.

M_{s}

is also shape dependent. The magnetization increases by Co and Er ion doping and decreases by Ti doping, which is caused by the different strain which appears in the nanoparticles and changes the exchange interaction constants in the doped states. The phonon energy for the

A_{g}

mode

ω

= 149 cm

^{- 1}

and their damping decreases or increases with increasing temperature, respectively. Both show a kink near the Neel temperature,

T_{N}

, which disappears by applying an external magnetic field. The influence of different ion doping on the band gap energy is also discussed. The doping effects can be used for different applications. Full article

(This article belongs to the Special Issue Hybrid Nanocomposites for Sustainable Development: Synthesis, Properties and Applications)

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16 pages, 2975 KiB

Open AccessArticle

Enhanced Multiferroic Properties of YFeO₃ by Doping with Bi³⁺

by Omar Rosales-González, Félix Sánchez-De Jesús, Fernando Pedro-García, Claudia Alicia Cortés-Escobedo, Màrius Ramírez-Cardona and Ana María Bolarín-Miró

Materials 2019, 12(13), 2054; https://doi.org/10.3390/ma12132054 - 26 Jun 2019

Cited by 46 | Viewed by 4771

Abstract

Tthe present work studied the cationic substitution of Y³⁺ by Bi³⁺ on the crystal structure of orthorhombic YFeO₃ and its effect over magnetic, dielectric and electric properties of multiferroic yttrium orthoferrite. Stoichiometric mixtures of Y₂O₃, Fe₂O₃ and Bi₂O₃ were mixed and milled for 5 h using a ball to powder weight ratio of 10:1 by high-energy ball milling. The obtained powders were pressed at 1500 MPa and sintered at 700 °C for 2 h. The test samples were characterized at room temperature by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and impedance spectroscopy (IS). The X-ray diffraction patterns disclosed a maximum solubility of 30 % mol. of Bi³⁺ into the orthorhombic YFeO₃. For higher concentrations, a transformation from orthorhombic to garnet structure was produced, obtaining partially Y₃Fe₅O₁₂ phase. The substitution of Bi³⁺ in Y³⁺ sites promoted a distortion into the orthorhombic structure and modified Fe-O-Fe angles and octahedral tilt. In addition, it promoted a ferromagnetic (FM) order, which was attributed to both the crystal distortion and Dzyaloshinskii-Moriya interaction. For doped samples, an increase in real permittivity values was observed, and reduced with the increase of frequency. This in good agreement with the Maxwell-Wagner effect. Full article

(This article belongs to the Special Issue Advances in Multiferroics)

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13 pages, 2742 KiB

Open AccessArticle

Synthesis of Phase Pure Hexagonal YFeO₃ Perovskite as Efficient Visible Light Active Photocatalyst

by Mohammed Ismael, Engy Elhaddad, Dereje H. Taffa and Michael Wark

Catalysts 2017, 7(11), 326; https://doi.org/10.3390/catal7110326 - 3 Nov 2017

Cited by 67 | Viewed by 9272

Abstract

Hexagonal perovskite YFeO₃ was synthesized by a complex-assisted sol-gel technique allowing crystallization at calcination temperatures below 700 °C. As determined by diffuse reflectance spectroscopy (DRS) and Tauc plots, the hexagonal YFeO₃ exhibits a lower optical band gap (1.81 eV) than the orthorhombic structure (about 2.1 eV or even higher) being typically obtained at elevated temperatures (>700 °C), and thus enables higher visible light photocatalysis activity. Structure and morphology of the synthesized YFeO₃ perovskites were analyzed by powder X-ray diffraction (XRD) and nitrogen adsorption, proving that significantly smaller crystallite sizes and higher surface areas are obtained for YFeO₃ with a hexagonal phase. The photocatalytic activity of the different YFeO₃ phases was deduced via the degradation of the model pollutants methyl orange and 4-chlorophenol. Experiments under illumination with light of different wavelengths, in the presence of different trapping elements, as well as photoelectrochemical tests allow conclusions regarding band positions of YFeO₃ and the photocatalytic degradation mechanism. X-ray photoelectron spectroscopy indicates that a very thin layer of Y₂O₃ might support the photocatalysis by improving the separation of photogenerated charge carriers. Full article

(This article belongs to the Special Issue Photocatalytic materials alternative to TiO₂ for environmental remediation, sustainable chemistry and energy conversion)

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Graphical abstract

6 pages, 931 KiB

Open AccessCommunication

Structure-Controllable Synthesis of Multiferroic YFeO₃ Nanopowders and Their Optical and Magnetic Properties

by Meng Wang, Ting Wang, Shenhua Song and Manlin Tan

Materials 2017, 10(6), 626; https://doi.org/10.3390/ma10060626 - 7 Jun 2017

Cited by 28 | Viewed by 4685

Abstract

Phase-pure hexagonal and orthorhombic YFeO₃ nanopowders are synthesized by low-temperature solid-state reaction along with Zr doping. The obtained powders are characterized by X-ray diffraction, field emission scanning electron microscopy, and physical property measurements. The hexagonal YFeO₃ exhibits a narrower optical band gap in comparison to the orthorhombic one, while the orthorhombic YFeO₃ presents better magnetic properties. The formation of hexagonal or orthorhombic phase can be effectively controlled by Zr doping. The temperature range of synthesizing the hexagonal YFeO₃ nanopowders is increased by ~200 °C due to Zr doping so that they can be easily synthesized, which possesses a finer particle size and a smaller optical band gap, making it favorable for optical applications. Full article

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