Renato F Jardim

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This work describes an easy synthesis (one pot) of MFe(2)O(4) (M = Co, Fe, Mn, and Ni) magnetic nanoparticles MNPs by the thermal decomposition of Fe(Acac)(3)/M(Acac)(2) by using BMI·NTf(2) (1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) or BMI·PF(6) (1-n-butyl-3-methylimidazolium hexafluorophosphate) ionic liquids (ILs) as recycling(More)
Polycrystalline Nd(1-x)Eu(x)NiO(3) (0≤x≤0.5) compounds were synthesized in order to investigate the character of the metal-insulator (MI) phase transition in this series. Samples were prepared through the sol-gel route and subjected to heat treatments at ∼1000 °C under oxygen pressures as high as 80 bar. X-ray diffraction (XRD) and neutron powder(More)
The thermal decomposition (TD) methods are among the most successful in obtaining magnetic nanoparticles with a high degree of control of size and narrow particle size distribution. Here we investigated the TD of iron(III) acetylacetonate in the presence of oleic acid, oleylamine, and a series of alcohols in order to disclose their role and also investigate(More)
Neutron diffraction on the double perovskite Sr(2)YRuO(6) with a quasi-fcc lattice of Ru moments reveals planar magnetic correlations that condense into a partial long-range ordered state with coupled alternate antiferromagnetic (AFM) YRuO(4) square layers coexisting with the short-range correlations below T(N1) = 32 K. A second transition to a fully(More)
A new method for analyzing second-order phase transitions is presented and applied to the polaronic system La(0.7)Ca(0.3)MnO3. It utilizes heat capacity and thermal expansion data simultaneously to correctly predict the critical temperature's pressure dependence. Analysis of the critical phenomena reveals second-order behavior and an unusually large heat(More)
Polycrystalline samples of PrBa2Cu3O7 y were prepared through two di erent routes: (a) mixing Pr6O11, BaCO3, and CuO; (b) sol-gel precursors. The samples were heat-treated in the temperature range 700 T 930 C and under di erent atmospheres, (Argon and air). Oxidation of these compounds, based on the results of thermogravimetric analysis, TGA, was performed(More)
We investigated the transport Barkhausen-like noise (TBN) by using nonlinear time series analysis. TBN signals were measured in (Bi,Pb)2Sr2Ca2Cu3O10+δ ceramic samples subjected to different uniaxial compacting pressures (UCP). These samples display similar intragranular properties but different intergranular features. We found positive Lyapunov exponents in(More)
We report measurements of the nonlinear refractive index, n(2), of nickel oxide nanoparticles (NPs) in toluene at 532 nm. The measurements were performed using the Z-scan technique with 80 ps laser pulses at 7 Hz. Large values of n(2) in the range of 10(-13)-10(-12) cm(2)/W were measured, and negligible two-photon absorption coefficient was estimated for(More)
We have measured magnetization M(T,H), electrical resistivity ρ(T,H), thermal conductivity κ(T,H), and thermopower S(T,H) of polycrystalline samples of Nd1−xEuxNiO3 (0 ≤ x ≤ 0.5) as a function of temperature and external magnetic field. The data indicate a metal-insulator (MI) transition in a wide range of temperature (200 < TMI < 325 K). The magnetic(More)
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