Phase diagram of pseudobinary CrBMnB and MnBFeB systems: Crystal structure of the low-temperature modification of FeB

Kanaizuka, T.

doi:10.1016/0022-4596(82)90202-x

Cited by 19 publications

(17 citation statements)

References 15 publications

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“…(1) Mn 2 B and MnB. In good agreement with the experimental findings, [22][23][24][25]47,48 our calculations reproduced successfully the experimentally observed structures and compositions for both Mn 2 B and MnB (cf. Table 1).…”

Section: First-principles Calculationssupporting

confidence: 86%

Variable-composition structural optimization and experimental verification of MnB₃and MnB₄

Niu

Chen

Ren

et al. 2014

Phys. Chem. Chem. Phys.

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In combination with variable-composition evolutionary algorithm calculations and first-principles calculations, we have systematically searched for all the stable compounds and their crystal structures in the extensively investigated binary Mn-B system. Our results have uncovered four viable ground-state compounds, with Mn2B, MnB, and MnB4, and previously never reported MnB3 and two metastable compounds, MnB2 and Mn3B4. Our calculations demonstrate that the early characterized mC10 structure of MnB4 showed dynamic instability with large imaginary phonon frequencies and, instead, a new mP20 structure is predicted to be stable both dynamically and thermodynamically, with a considerable energy gain and no imaginary phonon frequencies. The new MnB3 compound crystallizes in the monoclinic mC16 structure which lies 3.2 meV per atom below the MnB (oP8) ↔ MnB4 (mP20) tie-line at T = 0 K. Furthermore, these proposed phases have been verified by our annealed samples after arc-melting synthesis and corresponding powder XRD measurements.

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Section: First-principles Calculationssupporting

confidence: 86%

Variable-composition structural optimization and experimental verification of MnB₃and MnB₄

Niu

Chen

Ren

et al. 2014

Phys. Chem. Chem. Phys.

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“…The results of Rietveld refinement of high-resolution MnB and FeB patterns collected at room temperature are shown in Figure and Table S1. Both patterns match the known orthorhombic Pnma structure (“FeB-type”), , which consists of 1D zigzag chains of closely spaced (1.8 Å) B atoms running along the b crystallographic axis with Mn or Fe arranged in a distorted hexagonal network around these chains. This results in a highly bonded framework, with each metal atom coordinated by seven boron atoms within a sphere of 2.3 Å and six additional metal atoms within 2.7 Å.…”

Section: Resultssupporting

confidence: 70%

“…In fact, MnB sits at a phase boundary: moving one column to the left on the periodic table yields CrB, a transition metal monoboride with a modified structure (space group Cmcm ) from the Pnma structure of the common forms of MnB, FeB, and CoB. In fact, MnB itself can be stabilized in either the Pnma (as studied presently) or a low-temperature Cmcm structure . Therefore, we expect that FeB does not show the moment-bonding competition, and associated magnetostructural coupling that MnB does because the smaller size of the Fe atoms is not straining the B–B bonds.…”

Section: Competing Interactions and Magnetostructural Couplingmentioning

confidence: 90%

Magnetostructural Coupling Drives Magnetocaloric Behavior: The Case of MnB versus FeB

et al. 2019

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Materials with strongly coupled magnetic and structural transitions can display a giant magnetocaloric effect, which is of interest in the design of energy-efficient and environmentally-friendly refrigerators, heat pumps, and thermomagnetic generators. There also exist however, a class of materials with no known magnetostructural transition that nevertheless show remarkable magnetocaloric effects. MnB has been recently suggested as such a compound, displaying a large magnetocaloric effect at its Curie temperature (570 K) showing promise in recovering low-grade waste heat using thermomagnetic generation. In contrast, we show that isostructural FeB displays very similar magnetic ordering characteristics, but is not an effective magnetocaloric. Temperature-and field-dependent diffraction studies reveal dramatic magnetoelastic coupling in MnB, which exists without a magnetostructural transition. No such behavior is seen in FeB. Furthermore, the magnetic transition in MnB is shown to be subtly first-order, albeit with distinct behavior from that displayed by other magnetocalorics with first-order transitions. Density functional theory-based electronic structure calculations point to the magnetoelastic behavior in MnB as arising from a competition between Mn moment formation and B-B bonding.

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“…Second, transmission electron microscopy images of α-FeB particles exhibit contrasted parallel stripes . The same streaks are observed only in the nanodomains (30–100 nm) of β-FeB. ,,− Three hypotheses have been proposed to account for the elusive structure of α-FeB: ,,− (i) antisite mixing between Fe and B atoms; (ii) crystallization in a higher symmetry space group (SG); and (iii) intergrowth through stacking faults between two structure types . Notwithstanding, none of these attempts has provided a satisfactory solution able to reproduce experimental diffractograms.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Elusive Structure and Reactivity of Iron Boride α-FeB

et al. 2023

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Crystal structures can strongly deviate from bulk states when confined into nanodomains. These deviations may deeply affect properties and reactivity and then call for a close examination. In this work, we address the case where extended crystal defects spread through a whole solid and then yield an aperiodic structure and specific reactivity. We focus on iron boride, α-FeB, whose structure has not been elucidated yet, thus hindering the understanding of its properties. We synthesize the two known phases, α-FeB and β-FeB, in molten salts at 600 and 1100 °C, respectively. The experimental X-ray diffraction (XRD) data cannot be satisfactorily accounted for by a periodic crystal structure. We then model the compound as a stochastic assembly of layers of two structure types. Refinement of the powder XRD pattern by considering the explicit scattering interference of the different layers allows quantitative evaluation of the size of these domains and of the stacking faults between them. We, therefore, demonstrate that α-FeB is an intergrowth of nanometer-thick slabs of two structure types, β-FeB and CrB-type structures, in similar proportions. We finally discuss the implications of this novel structure on the reactivity of the material and its ability to perform insertion reactions by comparing the reactivities of α-FeB and β-FeB as reagents in the synthesis of a model layered material: Fe 2 AlB 2 . Using synchrotron-based in situ X-ray diffraction, we elucidate the mechanisms of the formation of Fe 2 AlB 2 . We highlight the higher reactivity of the intergrowth α-FeB in agreement with structural relationships.

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Phase diagram of pseudobinary CrBMnB and MnBFeB systems: Crystal structure of the low-temperature modification of FeB

Cited by 19 publications

References 15 publications

Variable-composition structural optimization and experimental verification of MnB₃and MnB₄

Variable-composition structural optimization and experimental verification of MnB₃and MnB₄

Magnetostructural Coupling Drives Magnetocaloric Behavior: The Case of MnB versus FeB

Revealing the Elusive Structure and Reactivity of Iron Boride α-FeB

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Phase diagram of pseudobinary CrBMnB and MnBFeB systems: Crystal structure of the low-temperature modification of FeB

Cited by 19 publications

References 15 publications

Variable-composition structural optimization and experimental verification of MnB3and MnB4

Variable-composition structural optimization and experimental verification of MnB3and MnB4

Magnetostructural Coupling Drives Magnetocaloric Behavior: The Case of MnB versus FeB

Revealing the Elusive Structure and Reactivity of Iron Boride α-FeB

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Product

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Variable-composition structural optimization and experimental verification of MnB₃and MnB₄

Variable-composition structural optimization and experimental verification of MnB₃and MnB₄