Untersuchung über die Umwandlungen im System Platin-Eisen

Kussmann, A.; Rittberg, Gotho Gräfin v.

doi:10.1515/ijmr-1950-411206

Cited by 8 publications

(7 citation statements)

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“…Nanoparticle preparation by the Fe 0 Pt II dibenzylether method 9 A stirred mixture of Pt(acac) 2 (296 mg; 0.75 mmol) and dibenzylether (15 mL; 15.645 g) is heated under argon from room temperature to 240 uC at a rate of 5 uC min 21 . When the temperature of the solution reaches 100 uC, Fe(CO) 5 (294 mg; 1.5 mmol), oleylamine (1.607 g; 6 mmol) and oleic acid (1.697 g; 6 mmol) are injected.…”

Section: Methodsmentioning

confidence: 99%

“…When the temperature of the solution reaches 100 uC, Fe(CO) 5 (294 mg; 1.5 mmol), oleylamine (1.607 g; 6 mmol) and oleic acid (1.697 g; 6 mmol) are injected. The temperature is then kept at 240 uC for 1 h, raised to 280 uC at a rate of 5 uC min 21 and maintained at this value for 2 h. During this reflux stage, a colourless liquid is distilled from the reaction mixture. This liquid is composed of toluene and benzaldehyde.…”

Section: Methodsmentioning

confidence: 99%

“…Oleylamine (139 mg; 0.52 mmol) and oleic acid (150 mg; 0.52 mmol) are added at 100 uC, causing the solution to turn from yellow to grey. Then the reaction mixture is heated to 240 uC at a rate of 5 uC min 21 , and lithium triethylborohydride solution (1 M in THF; 2.5 mL; 2.5 mmol) is added dropwise. After hydride addition is complete, the reaction temperature is increased to 258 uC, and kept at this value for 20 min.…”

Section: Methodsmentioning

confidence: 99%

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Core–shell structure of chemically synthesised FePt nanoparticles: a comparative study

et al. 2007

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We carried out solution synthesis of FePt nanoparticles through different chemical methods, using four "hot soap methods", i.e. the particle formation in the presence of surfactant molecules at high temperatures, and one polyol process. Structural and magnetic properties of the as-made particles pointed to a core-shell structure for the particles prepared with hot soap methods, with an irondepleted core surrounded by a pure iron shell. Such a structure has an impact on the magnetic properties of as-made particles since Fe atoms from shell are oxidised and non magnetic. We proved however that iron atoms of this shell are available during the formation of the ordered phase upon annealing: L1 0 phase for small particles, L1 2 for bigger ones. In contrast, the core-shell structure was not observed in the case of nanoparticles synthesised according to the polyol process. This outlines the key role of the stabilising ligands, long alkyl chain surfactants in the former case and tetraethylene glycol in the latter.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Core–shell structure of chemically synthesised FePt nanoparticles: a comparative study

et al. 2007

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“…This scaling presents a puzzle, as in Fe 0.65 Ni 0.35 , unlike in the other Invar alloy, the reduced magnetization exhibits an anomalous temperature dependence [2,3]. The most fascinating example of these phenomena has long been the Invar effect: The linear thermal expansion coefficient of the ferromagnets, α = (1/a) (∂a/∂T ) P , where a denotes the lattice parameter, is anomalously small [α(T ) ≪ 10 −5 K −1 ] over a wide range of temperature [5,6].…”

Section: Introductionmentioning

confidence: 99%

Magnetization, magnetostriction, and their relationship in Invar Fe$_{1-x}A_{x}$ ($A={\rm Pt},{\rm Ni}$)

Liot¹

2014

Preprint

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A method is proposed for investigating the spontaneous magnetization, the spontaneous volume magnetostriction, and their relationship in disordered facecentered-cubic Fe 0.72 Pt 0.28 and Fe 0.65 Ni 0.35 in the temperature interval 0 ≤ T /T C < 1. It relies on the disordered local moment formalism and the observation that the reduced magnetization in each of the investigated materials is accurately described by an equation of the formThe present approach yields interesting results. The alloys at zero Kelvin share several physical properties: the volume in a partially disordered local moment state shrinks as the fraction of Fe moments which point down increases in the interval 0 < x Fe↓ < 1/2, following closely V (0) − 4[V (0) − V (1/2)]x Fe↓ (1 − x Fe↓ ), while the magnetization collapses, following closely M (0) − 2M (0)x Fe↓ ; the volume in the homogeneous ferromagnetic state greatly exceeds that in the disordered local moment state; x Fe↓ (0) is close to zero. These common properties can account for a variety of intriguing phenomena displayed by both alloys, including the anomaly in the magnetostriction at zero Kelvin and, more surprisingly perhaps, the scaling between the reduced magnetostriction and the reduced magnetization squared below the Curie temperature. However, the thermal evolution of the fraction of Fe moments which point down depends strongly on the alloy under consideration. This, in turn, can explain the observed marked difference in the temperature dependence of the reduced magnetization between the two alloys.

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“…Disordered face-centered-cubic (fcc) Fe 0.72 Pt 0.28 and Fe 0.65 Ni 0.35 alloys have remained at the forefront of condensed matter theory for more than sixty years, owing to their rich variety of intriguing physical properties. Their linear thermal expansion coefficient (LTEC), α, is anomalously small [α(T ) ≪ 10 −5 K −1 ] over a wide range of temperature [1,2], a phenomenon known as the Invar effect. Their spontaneous volume magnetostriction, w s , measured at T = 0 K greatly exceeds that in body-centered-cubic (bcc) Fe and fcc Ni [3].…”

Section: Introductionmentioning

confidence: 99%

Conditions for the Invar effect in Fe$_{1-x}A_{x}$ ($A={\rm Pt},{\rm Ni}$)

Liot¹

2014

Preprint

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We present a necessary condition under which a collinear ferromagnet Fe 1−x A x (A = Pt, Ni) with disordered face-centered-cubic structure exhibits the Invar effect. The condition involves the rate at which the fraction of Fe moments that are antiferromagnetically aligned with the magnetization fluctuates as the system is heated, dx Fe↓ /dT . Another contributing factor is the magnetostructural coupling κ = −(1/V )(∂V /∂x Fe↓ ) T , where the volume V (T, x Fe↓ ) corresponds to a homogeneous ferromagnetic state, a partially disordered local moment state, or a disordered local moment state depending on the value of x Fe↓ . According to the criterion, the Invar phenomenon occurs only when the thermal expansion arising from the temperature dependence of the fraction of Fe moments which point down −1/3 κ dx Fe↓ /dT compensates for the thermal expansion associated with the anharmonicity of lattice vibrations in a wide temperature interval. Upon further investigation, we provide evidence that only alloys with strong magnetostructural coupling at zero Kelvin can show the Invar effect.

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Untersuchung über die Umwandlungen im System Platin-Eisen

Cited by 8 publications

References 0 publications

Core–shell structure of chemically synthesised FePt nanoparticles: a comparative study

Core–shell structure of chemically synthesised FePt nanoparticles: a comparative study

Magnetization, magnetostriction, and their relationship in Invar Fe$_{1-x}A_{x}$ ($A={\rm Pt},{\rm Ni}$)

Conditions for the Invar effect in Fe$_{1-x}A_{x}$ ($A={\rm Pt},{\rm Ni}$)

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