Magnetic properties of Cr–CrH and YFe2–YFe2H4

Crivello, Jean-Claude; Gupta, Michèle

doi:10.1016/j.jallcom.2004.09.080

Cited by 10 publications

(8 citation statements)

References 18 publications

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“…Each phase presents a similar trend with a reduction of its moment with increasing hydrogen concentration, up to the disappearance of magnetic ordering for x = 5. This behavior has already been shown by DFT calculations [30][31][32][33] and is explained by the stability of a compound dominated by chemical metal-hydrogen interaction at this rate, which converges to a Pauli paramagnetic state.…”

Section: B) Band Structure Calculationssupporting

confidence: 61%

Isotope effect on structural transitions in Y0.9Gd0.1Fe2(HzD1-z)4.2 compounds

Paul‐Boncour¹,

Voyshnis²,

Provost³

et al. 2013

Chem. Met. Alloys

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Y 0.9 Gd 0.1 Fe 2 (H z D 1-z) 4.2 compounds crystallize in a monoclinic structure at room temperature, with an increase of the cell parameters versus the H content. These compounds undergo a ferro-antiferromagnetic first-order transition, the transition temperature of which increases from 98 to 144 K for z going from 0 to 1, due to a strong magnetovolumic effect. Above room temperature (290-340 K), they display an order-disorder (O-D) transition from monoclinic towards a cubic structure, which has been studied by DSC and XRD versus temperature. This transition occurs via the presence of an intermediate phase, the structure of which depends on the H content. For z = 0 and 0.5 the intermediate phase is monoclinic, whereas an orthorhombic phase is observed for z = 0.75 and 1. In addition, for the H-rich compounds the orthorhombic phase disappears at a much lower temperature upon cooling than it appears upon heating. DFT band structure calculations for YFe 2 H x compounds showed that for 4 < x < 4.5, although the monoclinic phase is the more stable one, the energy of formation of the orthorhombic phase is only 0.1 kJ higher. For 4.5 < x ≤ 5 the orthorhombic phase becomes more stable. The sensitivity of the O-D transition to the H/D content could be related to a volume effect. At higher temperatures (T > 400 K), the thermal desorption studied by TGA shows a multipeak behavior that is not sensitive to the (H, D) isotope effect. Laves phases / Isotope effect / X-ray diffraction / Order-disorder transition / DFT calculation

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Section: B) Band Structure Calculationssupporting

confidence: 61%

Isotope effect on structural transitions in Y0.9Gd0.1Fe2(HzD1-z)4.2 compounds

Paul‐Boncour¹,

Voyshnis²,

Provost³

et al. 2013

Chem. Met. Alloys

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“…Band structure calculations on YFe2Hx have shown that the increase of the cell volume due to increasing hydrogen content stabilizes the ferromagnetic structure with a raise of the Fe moment, whereas the increase of the number of Fe-H bonding tend to reduce the Fe moment' until it become non stable in YFe2HS [20,21]. The magnetic properties of the YFez hydrides (deuterides) results therefore from a competition between volume and electronic change induced by the insertion ofH(D) atoms.…”

Section: Deuterium Ordering Vs Magnetic Ordermentioning

confidence: 99%

Deuterium ordering in Laves-phase deuteride YFe2D4.2

Ropka

Černý

Paul‐Boncour

et al. 2009

Journal of Solid State Chemistry

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The structure of Laves phase deuteride YFe2D4.2 has been investigated by synchrotron and neutron (ToP) powder diffraction experiments between 60 K and 370 K. YFe2D4.2 crystallizes below 323K in fully ordered monoclinic structure (s.g. Pc, Z 8, a = 5.50663(4), b = 11.4823(1), c = 9.42919(6) A, ~ 122.3314(5t, V = 503.765(3) A 3 at 290K) containing 4 yttrium, 8 iron and 18 deuterium atoms. Most ofD-D distances are withil1 the precision of the diffraction experiment longer than 2.1 A, the shortest ones are of 1.96 A. Seven iron atoms from eight are coordinated by deuterium in a trigonal bipyramid, similar to that in TiFeD1.95_2. The eights iron atom is coordinated by deuterium in a tetrahedral configuration. The iron coordination by deuterium, and iron-deuterium distances points to the importance of the directional bonding between iron and deuterium atoms. The lowering of crystal symmetry due to deuterium ordering occurs at much higher temperature than magnetic order, and is therefore one of the parameters which are at the origin of magnetic transition at lower temperatures.

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“…Structural order-disorder transitions from ordered towards disordered cubic structure are generally observed upon heating and occur at a TO-D temperature which depends on the H content [24,28,29]. Hydrogen insertion in these RFe2 compounds yields a decrease of the Curie temperature TC and large changes of the Fe-Fe and R-Fe interactions because of both structural variations and modification of the density of state (DOS) near the Fermi level (EF) [30].…”

Section: Introductionmentioning

confidence: 99%

Magnetic transitions with magnetocaloric effects near room temperature related to structural transitions in Y0.9Pr0.1Fe2D3.5 deuteride

Paul‐Boncour

Herrero

Shtender

et al. 2021

Journal of Applied Physics

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The structural and magnetic properties of Y0.9Pr0.1Fe2D3.5 deuteride have been investigated by synchrotron and neutron diffraction, magnetic measurements, and differential scanning calorimetry. Deuterium insertion induces a 23.5 % cell volume increase and a lowering of crystal symmetry compared to the cubic C15 parent compound (Fd-3m SG). The deuteride is monoclinic (P21/c SG) below 330 K and undergoes a first order transition between 330 and 350 K towards a pseudo-cubic structure (R-3m SG) with TO-D = 342(2) K. The compound is ferromagnetic, accompanied by a magnetostrictive effect below TC = 274 K. The analysis of the critical exponents indicates a second order type transition with a deviation from the isotropic 3D Heisenberg model towards the 3D XY model. This implies an easy plane of magnetization in agreement with cell parameter variation showing a planar magnetic orientation. A weak magnetic peak is even observed at the order-disorder transition with a maximum at 343 K. Magnetic entropy variations are characteristic of direct and reverse magnetocaloric effects at TC and TO-D respectively.

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Magnetic properties of Cr–CrH and YFe2–YFe2H4

Cited by 10 publications

References 18 publications

Isotope effect on structural transitions in Y0.9Gd0.1Fe2(HzD1-z)4.2 compounds

Isotope effect on structural transitions in Y0.9Gd0.1Fe2(HzD1-z)4.2 compounds

Deuterium ordering in Laves-phase deuteride YFe2D4.2

Magnetic transitions with magnetocaloric effects near room temperature related to structural transitions in Y0.9Pr0.1Fe2D3.5 deuteride

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