Influence of boron on the magnetic and transport properties of FeZr amorphous and nanocrystalline alloys

Barandiarán, J.M.; Gorría, P.; Sal, J.C. Gómez; Barquín, Luis Fernández; Kaul, S. N.

doi:10.1109/20.334218

Cited by 26 publications

(20 citation statements)

References 8 publications

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“…The composite is formed by two Fe-rich FeZrB(Cu) amorphous ribbons. These alloys, which were extensively studied due to their re-entrant spin-glass [11] and invar behaviors [12], are particularly appropriate since, depending on the Fe content, the T C is tunable between 200 and 400 K [13,14]. factor.…”

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confidence: 99%

Enhanced refrigerant capacity and magnetic entropy flattening using a two-amorphous FeZrB(Cu) composite

Álvarez

Llamazares

Gorría

et al. 2011

Applied Physics Letters

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The temperature dependence of the isothermal magnetic entropy change, ΔS M , and the The ideal Ericsson cycle (two isothermal and two isomagnetic field processes) is optimal for RT applications [2]. Its maximum efficiency is reached when the MCE exhibits a constant temperature dependence of the isothermal magnetic entropy change, ΔS M (T), within the operating temperature range [3]. This condition is difficult to be accomplished by a single material, but a composite made of two ferromagnetic materials may fulfill it provided that the difference between their Curie points, T C , is customized [4]. However, sintered mixtures of compounds are not well suited because they behave as a material with a single T C [5]. Instead of that, the design of specific composites [6][7][8] can lead to an enlargement of the MCE temperature span and an almost constant ΔS M (T) curve. The efficiency of the magnetic material in terms of the energy transfer between the cold (T cold ) and hot (T hot ) reservoirs, is quantified by its refrigerant capacity, RC, an important figure of merit that characterizes the magnetocaloric material [9,10]:where T cold and T hot are commonly selected as the temperatures corresponding to the full width at half maximum of ΔS M (T). In order to attain large RC values, a large magnetic entropy change over a wide temperature range is desirable. However, it has been shown that although the maximum value of ΔS M decreases, a large broadening of the ΔS M (T)curves can overcompensate such decrease, giving rise to a significant RC enhancement [7,10]. In turn, numerical calculations and their proof-of-principle in practical systemsshow that the design and practical realization of multiphase or composite magneto-3 caloric materials with optimized RC and ΔS M (T) curves is not a simple task [4][5][6]. For a two-phase composite the magnetic field variation of the RC is complex, and depends on several factors such as ΔT C and the shape, width and peak value of ΔS M (T) curve of the two constituents [6].In this letter we report on the MCE in a two-ribbon composite showing a larger RC with respect to that of each individual ribbon and a flattened ΔS M (T) curve. The composite is formed by two Fe-rich FeZrB(Cu) amorphous ribbons. These alloys, which were extensively studied due to their re-entrant spin-glass fig. 3). This RC enhancement is a consequence of the increase in δT FWHM . Nevertheless, a compromise between the value of the δT FWHM and the potential lost of efficiency of the machine (due to an increase of cycles in the heat exchange medium) is needed. In turns, the ΔS comp (T) curves under low magnetic field changes (μ o ∆H < 0.4 T) exhibit a double-peak profile [see inset of Fig. 2(a)], and the δT FWHM cannot be properly defined. 5Both, the enhancement of RC comp and the flattening observed in the ΔS comp curve stimulated us to measure the M(H) curves for the two-ribbon composite. This is important in order to assess whether the shape of M(H) curves is in some extend affected by dipolar interactions between ...

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confidence: 99%

Enhanced refrigerant capacity and magnetic entropy flattening using a two-amorphous FeZrB(Cu) composite

Álvarez

Llamazares

Gorría

et al. 2011

Applied Physics Letters

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“…However, in FeZrB amorphous alloys n exhibits a clear dependence on the applied magnetic field, with diminishing values down to n ≈ 0.82 for H ≥ 45 kOe, as H is increased in B2 sample. The origin of this n(H) dependence can be attributed to the fact that Fe 91 Zr 7 B 2 amorphous alloy is far from being magnetically saturated under an applied magnetic field H = 10 kOe, due to the complex competing magnetic interactions between Fe atoms [27,34]. For H > 10 kOe the M(H) curve reduces gradually its slope, thus explaining the almost constant value of n for H ≥ 45 kOe (see Fig.…”

Section: Resultsmentioning

confidence: 88%

“…Hence, for refrigeration purposes at room temperature it is important the feasible control of the T C value of the material via slight compositional changes. This requirement is fulfilled by FeZrB(Cu) metallic glasses, because T C follows an almost linear dependence with the Fe atomic percentage (with a negative slope), being nearly independent of the relative amount of Zr and B [27,30,34]. Therefore, the temperature range for the refrigeration cycle can be tuned between 100 and 350 K.…”

Section: Resultsmentioning

confidence: 93%

“…The addition of boron upto 10 wt%. gives rise to a large increase in T C (upto around 400 K), without losing complexity in the magnetic behaviour [27,28]. Moreover, these alloys have attracted huge attention because after adequate heat treatments a stable nanocrystalline microstructure is reached, thus displaying ultrasoft magnetic properties [29] and allowing the study of magnetic interactions between the Fe nanocrystals and the remaining amorphous matrix [30,31].…”

Section: Introductionmentioning

confidence: 99%

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Magneto-caloric effect in FeZrB amorphous alloys near room temperature

Álvarez

Marcos

Gorría

et al. 2010

Journal of Alloys and Compounds

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“…In addition, FeZrB metallic glasses combine relatively high values for the saturation magnetization (above 1.5 m B /Fe at.) with tunable T C values between 200 and 400 K [18,19].…”

Section: Introductionmentioning

confidence: 99%