This work describes the effect of laser power and exposure time on a sample octahedron‐shaped nanocrystals cobalt(II) oxide using Raman spectroscopy. Above certain value time, CoO rock salt evolves clearly to oxidized Co 3 O 4 normal spinel material because energy transfer consequent local heating induced by applied laser. The analysis this thermodynamic CoO–Co crossover in means spectroscopy has been performed. Copyright © 2017 John Wiley & Sons, Ltd.

The combination of low electrical resistance and high optical transparency in a single material is very uncommon. Developing these systems scientific challenge technological need, to replace ITO flexible electronic components other highly demanding applications. Here we report facile method prepare layers densely aligned ultrathin Au-nanowires, homogeneous over cm2 areas. as-deposited films show an electrical/optical performance competitive with graphene-based electrodes. Moreover, the...

The origin of dielectric anomalies and magnetodielectric response La(2)MnCoO(6) has been investigated by means ultra-high resolution synchrotron x-ray powder diffraction, neutron resistivity, magnetization measurements. study performed on two different bulk samples presenting degrees Mn/Co order: 95 74%. Beside the well-known influence magnetic properties, our results show that main effect disorder lies electrical resistivity. Bond distances clearly Mn(4+)/Co(2+) valence states in...

Oxidized cobalt ferrite nanocrystals with a modified distribution of the magnetic cations in their spinel structure give place to an unusual exchange-coupled system double reversal magnetization, exchange bias, and increased coercivity, but without presence clear physical interface that delimits two well-differentiated phases. More specifically, partial oxidation formation Fe vacancies at surface region entail cobalt-rich mixed spinel, which is strongly pinned by ferrimagnetic background...

Increased coercive and tunable exchange bias field values were registered in hybrid CoO@Fe3O4 core–shell octahedron-shaped nanoparticles of different average size. In this strained morphology, the metal cation chemical potentials at interface between antiferromagnetic ferrimagnetic oxides become a very dynamic variable. This causes effective magnetic anisotropy to increase type change after growing magnetite shell epitaxially onto cobalt oxide {111} surface facets and, consequently, tune effect.

Epitaxial magnetic heterostructures of $(\mathrm{soft}\ensuremath{-}){\mathrm{Fe}}_{3}{\mathrm{O}}_{4}/(\mathrm{hard}\ensuremath{-}){\mathrm{CoFe}}_{2}{\mathrm{O}}_{4}\phantom{\rule{0.28em}{0ex}}(001)$ have been fabricated with a varying thicknesses soft ferrite from 5 to 25 nm. We report change in the regime interaction between layers rigid-coupling exchange-spring behavior, above critical thickness ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ layer. show that symmetry and epitaxial matching spinel...

We are reporting the dielectric response of La1.5Sr0.5NiO4, a system that presents charge-ordered state above room temperature and rearrangement its charge-order pattern in region 160-200 K. A careful analysis role electric contacts used, sample thickness grain size on experimental data allows us to determine this material exhibits high values intrinsic constant. The variation constant with shows maximum pattern, which constitutes an evidence link between both phenomena.

High quality epitaxial thin films of LaCoO3 on SrTiO3 have been prepared by spin-coating a metal/polymeric aqueous solution. The (≈ 17 nm) are homogeneous and smooth over large areas. characteristic low-spin (LS) state is replaced higher spin configuration Co(III), due to strain-induced distortions the CoO6 octahedra, introducing ferromagnetic interaction negative magnetoresistance below TC = 85 K. This simple chemical method produces high-quality required for either fundamental studies or...

Chemical solution methods for thin-film deposition constitute an affordable alternative to high-vacuum physical technologies, like Sputtering, Pulsed Laser Deposition (PLD) or Molecular Beam Epitaxy (MBE).

Hole-doping into the Mott insulator LaMnO3 results in a very rich magneto-electric phase diagram, including colossal magnetoresistance and different types of charge orbital ordering. On other hand, presents an important catalytic activity for oxygen reduction, which is fundamental increasing efficiency solid-oxide fuel cells energy-conversion devices. In this work, we report chemical solution (water-based) synthesis high-quality epitaxial thin films LaMnO3, free defects at square-centimeter...

We report a rather high dependence of the dielectric permittivity on magnetic field in La2∕3Ca1∕3MnO3. The variation is maximum at around 270K, little above Curie temperature TC, and it reaches 35% under only 0.5T. attribute this phenomenon to space-charge or interfacial polarization produced between insulator metallic regions segregated intrinsically material TC.

The large magnetophoretic mobility stemming from the magnetic susceptibility and very small coercivity of octapod-shaped iron oxide nanoparticles improve their capability for separation.

We report the synthesis of epitaxial bilayers ultrathin La0.92MnO3/LaCoO3 (LMO/LCO) on SrTiO3 (STO) by polymer solution deposition. have achieved an excellent control over thickness (from ∼4 to ∼20 nm) and roughness films, which allows fabrication sharp interfaces required for their functionality. suggest that large increase in coercive field observed bilayer with respect isolated films LMO or LCO is due a strong ferromagnetic Mn–O–Co superexchange interaction at interface. Our results...

Abstract A combined Raman spectroscopy and magnetometry study of CoFe 2 O 4 –Cr 3 nanocomposites demonstrates the presence spin–phonon interactions exchange bias at interface between ferrimagnetic antiferromagnetic magnetoelectric Cr phases. The pinned layer uncompensated spins surface chromium oxide nanocrystals provides a source unidirectional anisotropy changes sign when transitioning from canted to frustrated situation, that is, as increasing percentage or decreasing in composites. This...

Magnetically induced catalysis can be promoted taking advantage of optimal heating properties from the magnetic nanoparticles to employed. However, when unprotected, these agents that are usually air-sensitive, get sintered under harsh catalytic conditions. In this context, we present, best our knowledge, first example air-stable that: 1) show excellent performance as in CO2 methanation catalyzed by Ni/SiRAlOx, with CH4 yields above 95 %, and 2) do not sinter reaction To attain both...

Abstract Polycrystalline samples of the charge ordered mixed oxide LaMn 0.5 Co O 3−δ (T CO = 400 K) have been prepared by nitrate decomposition method. These are biphasic, according to XRPD, and except one, oxygen defficient (δ ≈ 0.04‐0.05). The study dielectric properties these reveal that displays a high constant, specially at room temperature low frequencies. This ε′ r is seen be strongly dependent on particle size not so much defficiency best found in sample with biggest (ϕ 7 μm) for...

Abstract Misfit cobaltates ([Bi/Ba/Sr/Ca/CoO] n RS [CoO2] q ) constitute the most promising family of thermoelectric oxides for high temperature energy harvesting. However, their complex structure and chemical composition makes extremely challenging deposition by high-vacuum physical techniques. Therefore, many them have not been prepared as thin films until now. Here we report synthesis high-quality epitaxial representative members this compounds a water-based solution method. The show an...

We report the effect of interface symmetry-mismatch on magnetic properties LaCoO3 (LCO) thin films. Growing epitaxial LCO under tensile strain top cubic SrTiO3 (STO) produces a contraction along c axis and characteristic ferromagnetic response. However, we here that ferromagnetism in is completely suppressed when grown buffer layer rhombohedral La2/3Sr1/3MnO3 (LSMO), spite identical in-plane out-of-plane lattice deformation. This confirms it symmetry mismatch not just total strain, which...

Osteoarthritis, one of the most common joint degenerative pathologies, still has no cure, and current treatments, such as nonsteroidal anti-inflammatory drugs, can cause serious adverse effects when taken for a long time. Brown seaweed crude fucoidans are used clinical treatment several pathologies. In this study, therapeutical potential these biocompounds was analyzed in primary chondrocytes 260TT human chondrocyte cell line. Crude fucoidan from Undaria pinnatifida (Up) Sargassum muticum...

The suitability of a particular material for use in magnetic devices is determined by the process magnetization reversal/relaxation, which turn depends on anisotropy. Therefore, designing new ways to control anisotropy technologically important materials highly desirable. Here we show that epitaxial thin-films half-metallic ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) proximity thermodynamic equilibrium conditions during growth. We performed series X-ray diffraction and ferromagnetic...

The great tendency of Bi–Sr manganites to present charge order (CO) at very high temperatures and partial hybridization the 6s2 lone pair with O p-orbitals makes these materials interesting as potential candidates for obtaining dielectric constants small frequency dependence room temperature. We have studied properties Bi1−xSrxMnO3 (x=0.40,0.50) perovskites that CO well above temperature (TCO∼525K). Thick (∼4mm) samples exhibit, higher temperatures, values (above 106) constant along a huge...

Octahedron-shaped cobalt oxide nanocrystals undergo a structural evolution once coated with thin shells of manganese or ferrite, by means an asymmetric solid–solid diffusion occurring at the interface established between oxides. The resultant mixed ferrites in final nanostructures stem from phase progression associated nonequilibrium kinetic product that evolves to reach thermodynamic equilibrium. In this process, initially strained crystalline lattice closer influences progressive...

From electron spin resonance (ESR), magnetization, and thermoelectric power on the isostructural Mn2OBO3 Fe2OBO3, we have been able to establish important differences between magnetic properties of these two compounds. These are rationalized basis t2g versus eg electronic interactions, orbital occupancy, structure. For Mn2OBO3, propose possibility fast transfer Mn2+ Mn3+ cations, in a similar way 3+/4+ Zener pairs manganites. In Fe2OBO3 system, our main findings observation magnetization...