Abstract Mn1-xZnxFe2O4 (0 ≤ x ≤ 0.65) nanoferrite particles were used as filler in a silicone polymer matrix in order to obtain a composite material with the purpose of absorbing electromagnetic radiation. The composite was characterized by X-ray diffraction, transmission electron microscopy and force modulation microscopy (FMM) and the electromagnetic properties by means of network and impedance analyzers. It was observed that the composite with higher concentrations of Znx (x = 0.5 and 0.65) presented the lowest dispersion, due to the size of the zinc particles. This paper provides a framework for the practical application of absorbent composite materials of MnZn nanoferrite particles combined with silicone rubber to be used in 1-10 GHz frequency bands, with reflectivity values of -24 dB in the 6 GHz frequency range.

In this study, the effects of dopant concentrations on the structural and morphological characteristics of Zn1-xMnxO powders (x= 0.025, 0.05, 0.075, and 0.1 mole) synthesized by the Pechini method has been investigated. The powder was characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET) specific surface, energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and Spectroscopy with Fourier transform (FTIR). An XRD analysis of the powder showed the formation of ZnO phase with a typical single phase wurtzite structure. The EDX analysis revealed Mn incorporated in the ZnO structure. The particle size calculated by BET ranged from 24 to 63 nm, confirming the nanometric size of the powder particles. The SEM analysis revealed irregular shaped particle agglomerates and the presence of nanosheets. From FTIR it was confirmed the wurtzite structure in ZnO and ZnO nanoparticles doped with Mn.

Monocristales de ((1 - x)Pb(Zn1/3Nb2/3)O3-xPbTiO3-(1 - x)PZN-xPT) con estructura perovskita, muestran excelentes propiedades dieléctricas, ópticas y electrostrictivas en composiciones cerca a la frontera de fase morfotrópica (FFM), x <img src="/img/revistas/ince/v10n20/v10n20a02f6.jpg"> 0;09. La preparación de cerámicas con composiciones cercanas a la FFM por métodos convencionales, conduce a cerámicas con estructura pirocloro. En este trabajo, polvos de ((1-x)Pb(Zn1/3Nb2/3)O3- xPbTiO3-PZN-xPT) con x = 0;10 fueron sintetizados por el método de reacción por combustión. Como combustibles fueron usados: CO(NH2)2, C2H5NO2, CO(NH2)2/C2H5NO2 y C4H16N6O2. El resultado indica que el mayor porcentaje de fase perovskita (<img src="/img/revistas/ince/v10n20/v10n20a02f6.jpg"> 70 %) fue obtenido usando CO(NH2)2= C2H5NO2 (razón 50/50). Esta fase es mantenida al sinterizar la muestra a 1000 ° C en atmósfera de nitrógeno.

((1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3-(1-x)PZN-xPT) single crystals with perovskite structure near to the morphotropic phase boundary (MPB), x<img src="/img/revistas/ince/v10n20/v10n20a02f6.jpg">0; 09, exhibit unusual large dielectric and piezoelectric constants. Preparation of PZN-PT ceramics with composition near to the MPB using conventional methods leads to ceramics with pyrochlore structure. In this paper, ((1 - x)Pb(Zn1/3Nb2/3)O3-xPbTiO3-PZN-xPT) powders with x = 0; 10 were synthetized by the combustion reaction method. CO(NH2)2, C2H5NO2, CO(NH2)2/C2H5NO2 y C4H16N6O2 were used as fuels. Results show that a maximum of 70% of perovskite phase was obtained using CO(NH2)2= C2H5NO2 (in relation 50/50). The afore mentioned phase is preserved when sintering the sample at 1000 ° C, during 4h on nitrogen atmosphere.