Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Al system

Bodak, Ο. I.; Tokaychuk, Ya.; Manyako, Mykola; Pacheco, V.; Černý, Radovan; Yvon, K.

doi:10.1016/s0925-8388(02)01353-1

Cited by 10 publications

(14 citation statements)

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“…The amount of ternary 2/17 phases is in the range of 40-98 wt.%. Compared to the aluminum containing system Yb-Fe-Al which was studied at the same equilibrium temperature of 500 • C [3,4] the homogeneity ranges of the H2/17 and R2/17 phases are smaller: LuFe 9.5 type: 0-28 at.% Ga; PrFe 7 type: 16-35 at.% Ga. Similar to the aluminum system, the H1/7 phase occurs in as cast samples only and disappears during the annealing at 500 • C. In contrast to the aluminum system, however, a tetragonal phase with ThMn 12 type structure is not observed in the compositional region investigated.…”

Section: Resultsmentioning

confidence: 99%

“…To ensure homogeneity the ingots were remelted twice. Similar to the aluminum analogues investigated during our previous study [3] the samples were annealed at 500 • C in quartz ampoules under vacuum during 720 h and subsequently quenched in cold water. The main problem during sample preparation was the uncontrolled loss of ytterbium metal due to evaporation.…”

Section: Synthesismentioning

confidence: 99%

“…The data were collected on SNBL at ESRF (Grenoble, France) and analyzed by using the FullProf Suite software [7]. The structure models used for the hexagonal and orthorhombic phases were that reported in [3,4]. The site occupancies of ytterbium which is partially substituted by mixed Fe/Ga dumbells were constrained with respect to their sums (Yb + (Fe/Al) 2 = 100%) but left unconstrained with respect to the overall compositional ratios Yb/(Fe/Al) 2 of the crystals.…”

Section: X-ray Diffractionmentioning

confidence: 99%

“…Systematic studies of the aluminum substituted series R 2 Fe 17 − x Al x (R = Tb, Dy, Ho, Er) [2] and of the iron-rich corner of the ytterbium based Yb-Fe-Al phase diagram [3,4] have shown that the phase relations and structural properties change strongly as a function of both Al and R content. As the aluminum content increases, the hexagonal Th 2 Ni 17 type structure (or a substitution derivative of that structure) transforms, usually via a hexagonal TbCu 7 type derivative structure, into the rhombohedral Th 2 Zn 17 type structure (or a substitution derivative of that structure).…”

Section: Introductionmentioning

confidence: 99%

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Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Ga system

Tokaychuk

Bodak

Gorelenko

et al. 2006

Journal of Alloys and Compounds

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The iron-rich corner of the Yb-Fe-Ga phase diagram contains at least three phases. Two form in annealed samples (500 • C) and crystallize with either the hexagonal LuFe 9.5 type structure (space group P6 3 /mmc) at low Ga contents (0-28 at.% Ga), or the rhombohedral PrFe 7 (Th 2 Zn 17 ) type structure (space group R3m) at high Ga contents (16-35 at.% Ga), while one occurs in as-cast samples at intermediate Ga contents and crystallizes with the hexagonal TbCu 7 type structure (P6/mmm). As the gallium content is increased, the subcell volumes of the structures increase and the subcell ratios c/a decrease. The compounds are ferromagnetic and show magnetizations of upto σ = 50 emu/g at 10 kOe, and magnetic ordering temperatures of up to 80 • C. The direction of easy magnetization is close to the basal plane.

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Section: Resultsmentioning

confidence: 99%

Section: Synthesismentioning

confidence: 99%

Section: X-ray Diffractionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Ga system

Tokaychuk

Bodak

Gorelenko

et al. 2006

Journal of Alloys and Compounds

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“…However the slight Ce depletion and the presence of Ta suggest the possibility of minor deviations from the classic CaCu 5type crystal structure towards various channel disorders or "dumb-bell" problems characterized elsewhere. [48][49][50] These deviations were accounted for in our structural models and refinements [Figs. 4,5].…”

Section: A Sem/eds Examinations and Compositionmentioning

confidence: 99%

Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in theTa-,Cu-, andFe-Substituted
Lamichhane
¹
,
Onyszczak
²
,
Palasyuk
³

et al. 2019
Phys. Rev. Applied

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To reduce material and processing costs of commercial permanent magnets and to attempt to fill the empty niche of energy products, 10-20 MGOe, between low-flux (ferrites, alnico) and highflux (Nd2Fe14B-and SmCo5-type) magnets, we report synthesis, structure, magnetic properties and modeling of Ta, Cu and Fe substituted CeCo5. Using a self-flux technique, we grew single crystals of I-Ce15.1Ta1.0Co74.4Cu9.5, II-Ce16.3Ta0.6Co68.9Cu14.2, III-Ce15.7Ta0.6Co67.8Cu15.9, IV-Ce16.3Ta0.3Co61.7Cu21.7 and V-Ce14.3Ta1.0Co62.0Fe12.3Cu10.4. X-ray diffraction analysis (XRD) showed that these materials retain a CaCu5 substructure and incorporate small amounts of Ta in the form of "dumb-bells", filling the 2e crystallographic sites within the 1D hexagonal channel with the 1a Ce site, whereas Co, Cu and Fe are statistically distributed among the 2c and 3g crystallographic sites. Scanning electron microscopy, energy dispersive X-ray spectroscopy (SEM-EDS) and scanning transmission electron microscopy (STEM) examinations provided strong evidence of the single-phase nature of the as-grown crystals, even though they readily exhibited significant magnetic coercivities of ∼1.6-∼1.8 kOe caused by Co-enriched, nano-sized, structural defects and faults that can serve as pinning sites. Heat treatments at 1040 • C for 10 h and a hardening at 400 • C for 4 h lead to the formation of a so-called "composite crystal" with a bimodal microstructure that consists of a Tapoor matrix and Ta-rich laminal precipitates. Formation of the "composite crystal" during the heat treatment creates a 3D array of extended defects within a primarily single grain single crystal, which greatly improves its magnetic characteristics. Possible causes of the formation of the "composite crystal" may be associated with Ta atoms leaving matrix interstices at lower temperatures and/or matrix degradation induced by decreased miscibility at lower temperatures. Fe strongly improves both the Curie temperature and magnetization of the system resulting in (BH)max.≈13 MGOe at room temperature.

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Chemical Heterogeneity of a Crystal Built of Nanoscale Coherently Twinned Yb_2−x(Fe,Ga)_17+2x Polytypes

Filinchuk

Birkedal

Černý

et al. 2004

Chemistry A European J

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An X-ray study of single crystals extracted from an arc-melted Yb-Fe-Ga alloy showed that the diffraction pattern can be modeled by an intergrown crystal that has three sorts of domains: one hexagonal (1, LuFe(9.5) type) and two rhombohedral (2 a and 2 b, PrFe(7) type), the last two twinned by reticular merohedry. Crystals 1 and 2 are essentially polytypes with maximum degree of order (MDO polytypes), built up of nearly identical slabs that are stacked along [001] in ABAB em leader (1). and ABCABC em leader (2). sequences. Structure refinement was performed by a newly developed program that allowed us to refine several structures on a single data set. We found that the hexagonal and rhombohedral domains differ in chemical composition: while 1 shows a higher rate of Yb substitution by Fe(2) dumbbells, 2 shows partial substitution of Fe by Ga. Our observation of the nanoscale phase segregation is supported by latest finding of nonrandom distribution of stacking faults in a similar 2:17 alloy. An unequal distribution of chemical substitutions in 1 and 2 apparently compensates the inherent mismatch of basal plane dimensions of the individual MDO polytypes and thus constrains their cell parameters within the syntaxy. According to our knowledge this is the first example of two chemically distinct polytypes constituting a single crystal, refined on a single set of diffraction data.

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Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Al system

Cited by 10 publications

References 2 publications

Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Ga system

Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Ga system

Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in theTa-,Cu-, andFe-Substituted
Lamichhane
¹
,
Onyszczak
²
,
Palasyuk
³

et al. 2019
Phys. Rev. Applied

Chemical Heterogeneity of a Crystal Built of Nanoscale Coherently Twinned Yb_2−x(Fe,Ga)_17+2x Polytypes

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Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Al system

Cited by 10 publications

References 2 publications

Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Ga system

Structural and magnetic properties of iron-rich compounds in the Yb–Fe–Ga system

Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in theTa-,Cu-, andFe-SubstitutedLamichhane1, Onyszczak2, Palasyuk3 et al. 2019Phys. Rev. Applied

Chemical Heterogeneity of a Crystal Built of Nanoscale Coherently Twinned Yb2−x(Fe,Ga)17+2x Polytypes

Contact Info

Product

Resources

About

Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in theTa-,Cu-, andFe-Substituted
Lamichhane
¹
,
Onyszczak
²
,
Palasyuk
³

et al. 2019
Phys. Rev. Applied

Chemical Heterogeneity of a Crystal Built of Nanoscale Coherently Twinned Yb_2−x(Fe,Ga)_17+2x Polytypes