A5027553697- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Magnetic Properties and Applications
- Magnetic Properties of Alloys
- Microstructure and Mechanical Properties of Steels
- Rare-earth and actinide compounds
- Multiferroics and related materials
- Shape Memory Alloy Transformations
- Heusler alloys: electronic and magnetic properties
- Thermal Expansion and Ionic Conductivity
- Non-Destructive Testing Techniques
- Metallurgical and Alloy Processes
- Magnetic properties of thin films
- Aluminum Alloy Microstructure Properties
- Magnetism in coordination complexes
- Luminescence Properties of Advanced Materials
- Semiconductor materials and devices
- Metal and Thin Film Mechanics
- Induction Heating and Inverter Technology
- MXene and MAX Phase Materials
- Iron oxide chemistry and applications
- Structural Analysis of Composite Materials
- Organic and Molecular Conductors Research
- Membrane Separation Technologies
- Additive Manufacturing and 3D Printing Technologies
Federal Center for Technological Education of Minas Gerais
2016-2024
Universidade Federal Fluminense
2013-2022
Universidade Federal de Ouro Preto
2009-2011
University of Aveiro
2008-2009
Universidade Estadual de Campinas (UNICAMP)
2005-2007
University of Palermo
2007
Magnetic refrigeration is a good alternative to gas compression technology due higher efficiency and environmental concerns. Magnetocaloric materials must exhibit large adiabatic temperature variations entropic effect. MnAs shows the colossal magnetocaloric effect under high pressures or with Fe doping. In this work authors introduce class of materials—Mn1−xCuxAs—revealing peak −175J∕(Kkg) for 5T field variation at 318K ambient pressure.
In this work, we explore the magnetocaloric and magnetic properties of isoelectronic manganites R0.6Sr0.4MnO3 (R = La, Pr, Nd, Sm). Upon substitution La3+ by smaller rare-earth ions, average ionic radius 〈rA〉 A-site (A (R, Sr)) elements systematically decreases. It is found that, with decreasing 〈rA〉, magnetic-ordering temperature decreases from 341 K for La0.6Sr0.4MnO3 to 126 Sm0.6Sr0.4MnO3. Interestingly, magnetic-entropy change increases reaching ΔSM=−8.4 J/kg ΔH=0−20 kOe For manganites,...
We report a giant barocaloric effect in the spin-crossover compound $[\mathrm{Fe}{(\mathrm{hyptrz})}_{3}]{\mathrm{A}}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{H}}_{2}\mathrm{O}$ with $\mathrm{hyptzr}=4$-(3\ensuremath{'}-hydroxypropyl)-1,2,4-triazole and $\mathrm{A}=4$-chlorobenzenesulfonate. The origin of comes from strong coupling between lattice vibration electronic states ${t}_{2g}^{6}(S=0)$ $({t}_{2g}^{4}{e}_{g}^{2})(S=2)$ low high spin...
Conventional and anisotropic magnetocaloric effects were studied in cubic rare earth RNi2 (R=Nd,Gd,Tb) ferromagnetic intermetallic compounds. These three compounds are representative of small, null, large magnetocrystalline anisotropy the series, respectively. Magnetic measurements performed polycrystalline samples order to obtain isothermal data, which confronted with theoretical results based on mean field calculations. For R=Tb case, we explore crystalline electrical-field predict...
The La0.8Sr0.2MnO3 compound presents a ferromagnetic paramagnetic transition around room temperature to which reasonably high magnetocaloric effect is associated, turning this material of interest for application in magnetic refrigeration. We synthesized fiber single crystalline form by the Laser Heated Pedestal Growth method. sample was characterized x-ray diffraction and measurements as phase with required properties. measured properties under hydrostatic pressure pressures up 6 kbar...
The so-called half-metallic magnets have been proposed as good candidates for spintronic applications due to the feature of exhibiting a hundred percent spin polarization at Fermi level. Such materials follow Slater-Pauling rule, which relates magnetic moment with valence electrons in system. In this paper, we study bulk polycrystalline Fe2MnSi Heusler compound replacing Si by Ga determine how addition changes magnetic, structural, and half-metal properties compound. material does not...
This paper presents the results of an investigation magnetic and structural properties ${\text{Mn}}_{1\ensuremath{-}x}{\text{Fe}}_{x}\text{As}$ compounds under hydrostatic pressure chemical doping. The doping was performed by using low Fe levels $(x=0$, 0.003, 0.006, 0.010, 0.015, 0.018), which emulates negative effect on crystal structure. this approach were compared with physical (hydrostatic from 0 to 2.2 kbar) ${\text{Mn}}_{0.997}{\text{Fe}}_{0.003}\text{As}$. Both approaches exhibit...
In this study, how crystallographic texture and changes in microstructure affect the magnetic properties of a semi‐processed non‐oriented (NO) electrical steel, which is investigated its as‐received state after heat treatment, evaluated. Electron backscattered diffraction analysis shows variation with orientation changing from predominance γ α fibers to random one significant increase components <100> directions sheet plane, are desired for NO steels because they parallel direction...
In the present work we report on structural and magnetic behaviors of ${\text{PrNi}}_{5\ensuremath{-}x}{\text{Co}}_{x}$ intermetallic compounds. Due to competition between anisotropy energies both Co Pr sublattices, this series has a spin-reorientation phenomenon at low temperature (140 K). The Curie temperature, as function content, sudden increase above critical concentration ${x}_{c}\ensuremath{\sim}1.9$ feature is assigned percolation geometrically spaced clusters. This assumption...
The ferromagnetically coupled cobalt ion is observed to create a magnetocrystalline anisotropy in the PrNi5−xCox structure above critical composition of x = 2. competition energies between Co and Pr sublattices gives rise spin reorientation (SR) phenomenon compounds at low temperature (∼150 K) which then followed by magnetic transition higher temperature. Co-doping has strong influence on Curie temperature, changing it from ∼60 K (x 1.95) ∼537 3). entropy change associated with SR as well...
We improved the magnetocaloric potential of MnAs compounds by stoichiometry decrease in Mn through small substitution Fe and Cr. Isothermal magnetization measurements present hysteresis with metamagnetic processes near transition temperature, indicating a coexistence magnetic phases. Magnetic entropy change adiabatic temperature were obtained from heat capacity up to 380 K at fields 0 5 T. The results show high values properties, as relative cooling power, even presence hysteresis. can be...
Fe2MnSi fails to follow the Slater–Pauling rule. This phenomenon is thought originate from either: (i) an antiferromagnetic arrangement of Mn ions at low temperature and/or (ii) chemical disorder. An important insight on this issue could be achieved by considering Fe2MnSi1−xGax compounds, thoroughly studied here means magnetization, neutron diffraction and density functional calculations (DFT). Our results indicate that disorder (and not arrangement) responsible for deviation rule...
In this work, we report the theoretical and experimental investigations on magnetic magnetocaloric properties for Gd0.5Pr0.5Al2 compound in different fields. The magnetization features indicate that is ferrimagnetic at low temperatures. We also present data from X-ray circular dichroism (XMCD) experiments compound, with which have confirmed moments of Pr ions are antiparallel to Gd ions. parameters, ΔTS ΔST, were obtained calorimetric both curves normal inverse effect. A model coupling,...
The magnetic anisotropy of 3d sub-lattices has an important rule on the overall properties hard magnets. Intermetallics alloys with boron (R-Co/Ni-B, for instance) belong to those magnets family and are useful objects help understand behavior sub-lattice, specially when rare earth ions R do not have nature, like YCo4B ferromagnetic material. Interestingly, YNi4B is a paramagnetic material Ni contribute anisotropy. We focused therefore our attention YNi4–xCoxB series, x = 0, 1, 2, 3, 4. these...
A first-principles formalism is employed to investigate the interaction of iron oxide (FeO) with a boron nitride (BN) nanotube. The stable structure FeO-nanotube has Fe atoms binding N atoms, bond length roughly $\sim$2.1 \AA, and between O B 1.55 \AA. In case small FeO concentrations, total magnetic moment (4$\mu_{Bohr}$) times number in unit cell it energetically favorable units aggregate rather than randomly bind tube. As larger concentration case, we study BN nanotube fully covered by...