A5039878782- Metallic Glasses and Amorphous Alloys
- Magnetic Properties of Alloys
- Magnetic and transport properties of perovskites and related materials
- Shape Memory Alloy Transformations
- Magnetic Properties and Applications
- Microstructure and mechanical properties
- Magnetic properties of thin films
- High Entropy Alloys Studies
- Material Dynamics and Properties
- Phase-change materials and chalcogenides
- nanoparticles nucleation surface interactions
- Microstructure and Mechanical Properties of Steels
- Intermetallics and Advanced Alloy Properties
- Advanced Condensed Matter Physics
- Thermal Expansion and Ionic Conductivity
- Aluminum Alloys Composites Properties
- Rare-earth and actinide compounds
- Theoretical and Computational Physics
- Advanced Materials Characterization Techniques
- Multiferroics and related materials
- Glass properties and applications
- High-Temperature Coating Behaviors
- Thermal and Kinetic Analysis
- Advanced materials and composites
- Ferroelectric and Piezoelectric Materials
Universidad de Sevilla
2015-2024
University of South Florida
2015
Leibniz Institute for Solid State and Materials Research
2004-2005
Instituto de Ciencia de Materiales de Sevilla
2005
Consejo Superior de Investigaciones Científicas
2004-2005
Warsaw University of Technology
2004-2005
In the past 20 years, there has been a surge in research on magnetocaloric response of materials, due mainly to possibility applying this effect for magnetic refrigeration close room temperature. This review is devoted main families materials suitable application and procedures proposed predict their response. Apart from possible technological applications, we also discuss use characterization gain fundamental insight into nature underlying phase transition.
The field dependence of the magnetic entropy change can be expressed as ΔSM∝Hn. For soft amorphous alloys n=1 well below Curie temperature (TC), n=2 in paramagnetic range, and n≈0.75 for T=TC. first value explained with simple arguments, is a consequence Curie-Weiss law, but n(TC) deviates from mean predictions. From Arrott-Noakes equation state, relation between critical exponents has been obtained, showing remarkable agreement experimental data (for an example alloy, predicted n=0.72...
The universal character of the recent experimentally found master curve for magnetic entropy change, ΔSM, in studies magnetocaloric response materials is analytically justified by using scaling arguments. validity obtained relations checked against experimental data as well mean field and Heisenberg models. curves are unique each universality class. It shown that can be practically constructed two different ways, reducing number required parameters with respect to previous phenomenological...
The effect of Co addition on the magnetocaloric amorphous alloys with Nanoperm-type composition has been studied for temperatures above room temperature. produces an increase in maximum magnetic entropy change and a shift its associated temperature to higher temperatures. refrigerant capacity (RC) value obtained this study is 82Jkg−1 applied field H=15kOe. This ∼30% larger than that Mo-containing Finemet-type alloy measured under same experimental conditions. However, RC alloys, when...
The magnetocaloric effect of Fe91−xMo8Cu1Bx (x=15,17,20) amorphous alloys has been studied. temperature the peak magnetic entropy change can be tuned by altering Fe∕B ratio in alloy, without changing its magnitude, ∣ΔSMpk∣. average contribution Fe atoms to ∣ΔSMpk∣ increases with increasing B content. This is correlated increase low mean moment Fe. A recently proposed master curve behavior for also followed these and common all them.
The refrigerant capacity (RC) of Fe68.5Mo5Si13.5B9Cu1Nb3 alloy is studied. For the amorphous sample, RC=63Jkg−1 for an optimal reversible cycle with cold and hot ends at 328K 520K, respectively, a maximum applied field H=15kOe. Nanocrystallization diminishes both peak entropy change RC material. Although measured smaller than Gd5Ge1.9Si2Fe0.1 (240Jkg−1 H=50kOe), Mo-Finemet more 20 times cheaper, employed smaller, temperature span increased. This makes this promising material high-temperature...
LaFeO3 perovskite ceramics have been prepared via reaction flash technique using Fe2O3 and La2O3 as precursors. The obtained pellets investigated several techniques. formation of has clearly confirmed by X-ray diffraction. scanning electron microscopy micrographs shown the microporous character due to low temperature dwell time used in synthesis process (10 min at 1173 K). orthorhombic-rhombohedral phase transition observed approximately 1273 K differential thermal analysis measurements,...
Herein, it is reported the concomitant synthesis and sintering in a single step of (Mn0.2Co0.2Ni0.2Cu0.2X0.2)Fe2O4 (X=Fe, Mg), spinel-structured high-entropy oxides, by reactive flash technique. A phase, identified with spinel crystal structure Fd3̅m, was obtained just 30 min at furnace temperature 1173 K. The structural magnetic properties prepared compounds were assessed combined use various techniques, aiming to understand correlations between functional structure. Characteristic features...
The influence of the partial substitution B by Ge on magnetocaloric response Fe78Co5Zr6B10Cu1 is studied. addition produces a reduction in temperature at which peak entropy change takes place, as well slight decrease magnitude peak, ∣ΔSMpk∣. refrigerant capacity, RC, and its field dependence also analyzed: although increases RC Co-containing alloy, largest value corresponds to Co- Ge-free alloy. This will be discussed basis recently proposed universal curve for magnetic change, followed...
The influence of different compositional modifications on the magnetic entropy change and refrigerant capacity Finemet, Nanoperm, HiTperm, bulk amorphous alloys is presented. For all studied alloys, field dependence exhibits a quadratic in paramagnetic regime, linear ferromagnetic temperature range, potential law with exponent ∼0.75 at Curie temperature. This can be explained using critical exponents transition. It shown that for similar series, follows master curve behavior.
In recent years, the magnetocaloric effect is studied not only for search of potential magnetic refrigerant materials but also analysis critical phenomena. both cases, demagnetizing field might have a notable influence on results. this work, we carry out systematic study, based theoretical simulations, factor properties. On one hand, show that affects slightly entropy change (ΔSM), reducing its magnitude and shifting peak to higher temperatures. other it dramatically exponent n dependence...
Reactive flash-sintering technique has been used in order to obtain strontium ferrite magnets from a mixture of SrCO3 and Fe2O3 commercial powders. This allows preparing sintered SrFe12O19 at furnace temperature just 973 K during 2 min by applying modest field 40 V cm-1, instead the conventional sintering process employed magnet manufacturing that demands high long dwell times. Analysis structural magnetic properties were performed as function time which flash event was held. Mössbauer...
The thermal memory effect, TME, has been studied in Ni55Fe19Ga26 shape alloys, fabricated as ribbons via melt-spinning and pellets arc-melting, to evaluate its dependence on the martensitic structure macrostructure of samples. When reverse transformation is interrupted, a kinetic delay subsequent complete only evident ribbon samples, where 14M modulated dominant phase. In contrast, degradation or presence gamma-phase significantly reduces observed TME. such cases, magnitude TME approaches...
The magnetocaloric response of mechanically alloyed Fe75Nb10B15 powders was studied for samples with different amorphous and nanocrystal volume fractions. Thermomagnetic properties scale following a Ω3 law milling processes, where Ω is the frequency. Curie temperature phase increases as fraction due to its progressive enrichment in B. peak magnetic entropy change, |ΔSMpk|, well refrigerant capacity increase increasing fraction. field dependence |ΔSMpk| can be explained by multiphase...