Formation of oxide phases in the system Fe2O3−Gd2O3

Musić, Svetozar; Ilakovac, V.; Ristić, Mira; Popović, Stanko

doi:10.1007/bf01197655

Cited by 18 publications

(7 citation statements)

References 23 publications

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“…Under the harsh decomposition conditions for complex 4, an extra two small peaks appeared at around 36.73°and 44.9°, attributed to Gd 3 Fe 5 O 12 (ICDD: 00-048-0077, space group: Ia3̅ d). 80 However, the main phase was orthorhombic GdFeO 3 (ICDD: 01-074-1476, space group: Pbnm). 78,79 Table 2 shows unit cell parameters a, b, and c, and the particle size determined from the Scherrer equation for all four phases.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Heterometallic 3d–4f Complexes as Air-Stable Molecular Precursors in Low Temperature Syntheses of Stoichiometric Rare-Earth Orthoferrite Powders

et al. 2020

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Four 3d−4f hetero-polymetallic complexes [Fe 2 Ln 2 ((OCH 2 ) 3 CR) 2 (O 2 C t Bu) 6 (H 2 O) 4 ] (where Ln = La (1 and 2) and Gd (3 and 4); and R = Me (1 and 3) and Et (2 and 4)) are synthesized and analyzed using elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and SQUID magnetometry. Crystal structures are obtained for both methyl derivatives and show that the complexes are isostructural and adopt a defective dicubane topology. The four heavy metals are connected with two alkoxide bridges. These four precursors are used as single-source precursors to prepare rare-earth orthoferrite pervoskites of the form LnFeO 3 . Thermal decomposition in a ceramic boat in a tube furnace gives orthorhombic LnFeO 3 powders using optimized temperatures and decomposition times: LaFeO 3 formed at 650 °C over 30 min, whereas GdFeO 3 formed at 750 °C over 18 h. These materials are structurally characterized using powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray map spectroscopy, and SQUID magnetometry. EDX spectroscopy mapping reveals a homogeneous spatial distribution of elements for all four materials consistent with LnFeO 3 . Magnetic measurements on complexes 1−4 confirm the presence of weak antiferromagnetic coupling between the central Fe(III) ions of the clusters and negligible ferromagnetic interaction with peripheral Gd(III) ions in 3 and 4. Zero-field-cooled and field-cooled measurements of magnetization of LaFeO 3 and GdFeO 3 in the solid-state suggest that both materials are ferromagnetic, and both materials show open magnetic hysteresis loops at 5 and 300 K, with M sat higher than previously reported for these nanomaterials. We conclude that this is a new and facile low temperature route to these important magnetic materials that is potentially universal, limited only by what metals can be programmed into the precursor complexes.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Heterometallic 3d–4f Complexes as Air-Stable Molecular Precursors in Low Temperature Syntheses of Stoichiometric Rare-Earth Orthoferrite Powders

et al. 2020

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“…The doping methods have been applied in a series of author's studies, among others, in the study of the phase transition in titanium dioxide [18,19], biomineralization processes in the oyster Ostrea edulis [20,21], crystalline phases in intermetallic oxides [22][23][24][25][26][27], precipitation processes in Al-Zn alloys [11][12][13]19].…”

Section: Selected Studies With Application Of Doping Methodsmentioning

confidence: 99%

“…are replaced by other cations, have been systematically investigated by XRD, TEM, FE SEM, FTIR, and Mössbauer spectroscopies and other supplementary techniques (collaboration with S. Musić, M. Ristić, G. Štefanić, Ruđer Bošković Institute, Zagreb) in order to study formation of oxide phases and solid solutions, crystallinity, (nano)crystallite size, strain in the crystallites, properties at HT, phase transitions, and phase diagrams vs. physical and chemical properties. As an example of those studies, the systems α-Fe 2 O 3 -Ln 2 O 3 , Ln = Eu, Gd, are described shortly [22][23][24][25][26][27].…”

Section: Crystalline Phases In Intermetallic Oxidesmentioning

confidence: 99%

“…Molar fractions of the observed crystalline phases (at RT), estimated by the application of the doping method (i), as a function of the initial molar fractions of α-Fe 2 O 3 and Ln 2 O 3 , are shown inFigure 6. Experimental procedures and obtained results, as well as the crystal data of the phases appearing in the systems α-Fe 2 O 3 -Ln 2 O 3 (at RT) are given in detail in References[22][23][24][25][26][27].…”

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Quantitative Phase Analysis by X-ray Diffraction—Doping Methods and Applications

Popović

2020

Crystals

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X-ray powder diffraction is an ideal technique for the quantitative analysis of a multiphase sample. The intensities of diffraction lines of a phase in a multiphase sample are proportional to the phase fraction and the quantitative analysis can be obtained if the correction for the absorption of X-rays in the sample is performed. Simple procedures of quantitative X-ray diffraction phase analysis of a multiphase sample are presented. The matrix-flushing method, with the application of reference intensities, yields the relationship between the intensity and phase fraction free from the absorption effect, thus, shunting calibration curves or internal standard procedures. Special attention is paid to the doping methods: (i) simultaneous determination of the fractions of several phases using a single doping and (ii) determination of the fraction of the dominant phase. The conditions to minimize systematic errors are discussed. The problem of overlapping of diffraction lines can be overcome by combining the doping method (i) and the individual profile fitting method, thus performing the quantitative phase analysis without the reference to structural models of particular phases. Recent suggestions in quantitative phase analysis are quoted, e.g., in study of the decomposition of supersaturated solid solutions-intermetallic alloys. Round Robin on Quantitative Phase Analysis, organized by the IUCr Commission on Powder Diffraction, is discussed shortly. The doping methods have been applied in various studies, e.g., phase transitions in titanium dioxide, biomineralization processes, and phases in intermetallic oxide systems and intermetallic alloys.

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“…25 However, stoichiometric Gd x Fe y O z oxides such as GdFeO 3 , GdFe 2 O 4 , Gd 3 FeO 6 , and Gd 3 Fe 5 O 12 had been prepared at high temperature syntheses through annealing (>500 • C). 10,11,[26][27][28][29][30][31][32][33][34][35][36][37][38] Therefore, high temperature synthesis should be used to increase Gd(III) doping mole percents.…”

Section: Doping Mole Percent and Surface Composition In Nanoparticlesmentioning

confidence: 99%

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

Choi

Baek

et al. 2013

AIP Advances

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Two samples of ultra small Gd(III) doped iron oxide nanoparticles were prepared to investigate Gd(III) doping effect on longitudinal (r1) and transverse (r2) water proton relaxivities. Gd(III) doping mole percents were 0.2 and 0.4 for samples 1 and 2, respectively. Average particle diameters were 2.5 to 2.1 nm for samples 1 and 2, respectively. Reduced r1 and r2 values were observed in both samples. We attributed this to reduced magnetizations arising from opposing effect of Gd(III) to net magnetizations of Fe(III)/Fe(II) in oxide nanoparticles

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Formation of oxide phases in the system Fe2O3−Gd2O3

Cited by 18 publications

References 23 publications

Heterometallic 3d–4f Complexes as Air-Stable Molecular Precursors in Low Temperature Syntheses of Stoichiometric Rare-Earth Orthoferrite Powders

Heterometallic 3d–4f Complexes as Air-Stable Molecular Precursors in Low Temperature Syntheses of Stoichiometric Rare-Earth Orthoferrite Powders

Quantitative Phase Analysis by X-ray Diffraction—Doping Methods and Applications

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

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