Polymer based LaFeO3-Poly(vinylidene fluoride) hybrid nanocomposites: Enhanced magneto-electric coupling, magnetoimpedance and dielectric response (original) (raw)
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Materials Letters, 2018
Room temperature magnetoelectric coupling, magnetic field dependent dielectric and ac electrical properties of xLa 0.7 Sr 0.3 MnO 3-(1 À x) Poly(vinylidene fluoride) (x = 0.5, 0.6 and 0.7) nanocomposites have been investigated. The magnetoelectric voltage coefficients are found to 0.25and0.25 and 0.25and0.16 mV/cmOe for transverse and longitudinal configurations. Dielectric constants for all the compositions are increased with increase in magnetic field. Magnetodielectric value is estimated to $16% due to the magnetostriction property of the samples. The fitted value of Nyquist plots reveals the dominant role of the grain boundaries of La 0.7 Sr 0.3 MnO 3 nanoparticles and modified grain boundaries due to Poly(vinylidene fluoride) in the samples. With the application of magnetic field the relaxation frequencies are shifted towards the higher frequency region attributing to the magnetic field dependent relaxation process in the system.
Journal of Non-Crystalline Solids, 2013
Iron oxide magnetic nanoparticles (IOMNPs) with average size of~15 nm, synthesized by a co-precipitation technique were included in a poly(vinylidene fluoride) (PVDF) matrix with the objective to produce IOMNPs/PVDF multiferroic nanocomposites by solvent casting and melt processing. Increasing concentration of the IOMNPs nucleates the piezoelectric β-phase of the polymer, decreases the degree of crystallinity and increases the melting temperature of the polymer matrix leading to electroactive materials with large potential for sensor and actuator applications. The macroscopic magnetic and dielectric response of the composites depends on the weight fraction of IOMNPs nanoparticles in the nanocomposite, with both magnetization and dielectric constant increasing for increasing filler content. A typical superparamagnetic behavior was observed in the IOMNPs/PVDF composites.
Journal of Magnetism and Magnetic Materials, 2019
Room temperature magnetoimpedance and magnetodielectric effects for (100 − x)% LaFeO 3 − x% organic paraffin wax (x = 0, 0.5, 1, 1.5%) hybrid nanocomposites have been investigated. The enhancement of magnetoimpedance (∼226%) and magnetodielectric (∼75%) effects at low frequency region are obtained for x = 0.5% nanocomposites for strain mediation of piezomagnetic materials. The observed currentvoltage characteristics both in absence and presence of magnetic field at room temperature have corroborated with the enhanced effect. It is also showing electrical memory effect with electrical switching. The Nyquist plots have been fitted considering the parallel combination of resistance-constant phase element circuit. AC electrical studies reveal the conduction mechanism in the system controlling through the grain and grain boundaries of nanocomposites. The minimum grain and grain boundaries resistance are found for x = 0.5% nanocomposites. The electric modulus of these nanocomposites has been studied to separate the grain and grain boundaries contributions of the system. A phenomenological model has been demonstrated to explain the observed result considering the barrier width of paraffin wax layer across the grain boundaries of LaFeO 3 nanoparticles. The observed transport behavior attributes the phenomenological model. The organic hybrid nanocomposites (x = 0.5%) may be worked as a resistance-capacitance-inductance circuit with voltage magnification.
Journal of Materials Science: Materials in Electronics, 2019
Eco-friendly, magnetoelectric LaFeO 3-HoMnO 3 nanocomposites are synthesized with different weight percentage, and highlighted their observed magnetoelectric coupling, electrical transport and dielectric properties. X-ray diffraction pattern and field emission scanning electron microscope images approve the formation of LaFeO 3 and HoMnO 3 phases without the presence of any extra phase. These composites reveal the strain mediated magnetoelectric effect with longitudinal (α E33) and transverse (α E31) configurations at lower frequency region under an external magnetic field. Maximum values of α E31 and α E33 are found to ~ 0.54 and ~ 0.31 mV/cm-Oe, respectively for 0.3LaFeO 3-0.7HoMnO 3 nanocomposites. The electronic transport has been examined by impedance spectroscopy technique for understanding the grain boundary and grain effects in resistive and capacitive behavior of the materials considering an idealized simulated circuit. Temperature dependent Nyquist plots show the non-Debye type phenomena as well as semiconductor in nature (i.e., negative temperature coefficient of resistance) of the materials. Electrical susceptibility reveals the domain motion of the system, which is corresponding to the electrostriction property. The electrical conductivity with frequency follows the Joncher's single power law and it is controlled through large and small polaron tunneling model. The synthesized nanocomposites are a capable candidate to offer some helpful ideas for developing the lead free device applications.
Ferroelectrics, 2019
Magnetoelectric composites of xLaFeO 3-(1 À x)Pb(Zr 0.58 Ti 0.42)O 3 (x ¼ 0.2 and 0.3) have been prepared by pyrophoric reaction process. The observed room temperature magnetoelectric coefficient is enhanced with the increase of LaFeO 3 content in nanocomposites. The maximum value of magnetoelectric coupling is found to be 1.5mV/cm−Oeand1.5 mV/cm-Oe and 1.5mV/cm−Oeand0.3 mV/cm-Oe, which may be due to the strain mediation of piezomagnetic phase and magnetodielectric property of the material. The frequency dependent AC conductivity at several temperatures indicates the thermally activated conduction process in the system. The electrical conductivity (both AC and DC) shows positive temperature coefficient resistance effect of the system where AC conductivity obeys Jonscher's power law. It demonstrates the hopping mechanism via small as well as large polaronic conduction process in the system. Maximum change of magnetoimpedance ($185%) is observed at a frequency of 100 Hz at room temperature. The observed magnetoimpedance effect can be explained considering the skin effect. The magnetocapacitance effect shows the maximum value ($60%) at lower frequency regime at room temperature attributing the evidence of Maxwell-Wagner interfacial or space charge polarization in the sample. At room temperature the magnetic field dependent capacitance of these samples is corroborating the evidence of magnetoelectric coupling.
AIP Advances, 2013
We have investigated the structure, magnetic and dielectric properties of PVDF-La 0.7 Sr 0.3 MnO 3 polymer nanocomposite thick film fabricated by dip coating technique along with the magnetodielectric effect. The structure and dielectric properties show the enhanced β phase in the composite compared to the PVDF film. The coupling between the ferroelectric and magnetic phases in the composite is revealed in the form of dielectric anomaly at the ferromagnetic Curie temperature. We observed 1.9% magnetodielectric effect at 300 K with the possibility of enhanced effect near the transition temperature. In addition, the analysis of the electric modulus indicates that the composite exhibits interfacial related relaxation and it follows Arrhenius Law. Our study suggests that the ac conductivity of the PVDF-La 0.7 Sr 0.3 MnO 3 composite could be explained by correlated barrier hopping mechanism.
Flexible and self-standing inorganic-organic hybrid films of silica coated Fe 3 O 4 nanoparticles and polyvinylidene fluoride (PVDF) polymer with significant magneto-dielectric coupling have been prepared at low temperature by a simple solvent casting method. PVDF films with two different concentrations of silica coated Fe 3 O 4 (4.76 and 9.09 wt%) have been developed and well characterized using different techniques like XRD, TEM and IR. The thin film coating of silica on Fe 3 O 4 could be detected by IR and TEM. The ferroelectric, magnetic and magneto-capacitive measurements at room temperature confirm the multiferroic nature of the composite films with significant magneto-electric coupling between Fe 3 O 4 and PVDF. † Electronic supplementary information (ESI) available: IR spectra of Fe 3 O 4 and silica coated Fe 3 O 4 , magnetization as a function of temperature of PVDF-4.76 wt % Fe 3 O 4 and PVDF-9.09 wt% Fe 3 O 4 , and magnetodielectric coupling of the Fe 3 O 4 -SiO 2 composite. See
Magneto-dielectric properties of polymer-Fe3O4 nanocomposites
Journal of Magnetism and …, 2008
The aim of this research is to elucidate the size effect of magnetic nanoparticles on the resultant magneto-dielectric properties of polymer nanocomposites at radio frequencies. The block copolymer of [styrene-b-ethylene/butylene-b-styrene] (SEBS) was utilized as a matrix for the templating of magnetic nanoparticles. Surfactant-modified iron oxide (Fe 3 O 4 ) nanoparticles of various sizes were successfully synthesized by a seed-mediated growth method. The surfactant prevented Fe 3 O 4 aggregation and provided compatibility with the polymer matrix. The nucleation and growth of Fe 3 O 4 nanoparticles was controlled by changing the concentration ratio of surfactant to iron-precursor. The free iron ions present during synthesis are the major factor contributing to the growth of larger particles. The Fe 3 O 4 nanoparticle critical size for superparamagnetic to ferrimagnetic transition was determined to be near 30 nm at room temperature. The dielectric permittivity ðe r Þ of the polymer composite increased with increasing amount of Fe 3 O 4 doping, and was not influenced by nanoparticle size. However, the magnetic permeability (m r ) of the composites was significantly influenced by the size of Fe 3 O 4 nanoparticles templated within the block copolymer matrix due to thermal energy fluctuations from the nanoparticle surroundings.
Journal of Materials Science: Materials in Electronics, 2019
Effect of particles size on the behavior of magnetoimpedance, magnetodielectric and detailed electrical properties of structural characterized LaFeO 3 nanoparticles prepared through chemical 'pyrophoric reaction' technique having particles size of ~ 21, 43 and 51 nm have investigated. Dielectric constant of these nanoparticles gives the evidence of space charge polarization in the sample at lower frequency regime. Maximum magnetodielectric effect is obtained to ~ 61% at room temperature for particle size of ~ 21 nm, which may be due to the large surface to volume ratio of this nanoparticles compared to other particles size attributing the enhancement of space charge polarization. The maximum value of magnetoimpedance is found to ~ 92% for ~ 21 nm nanoparticle at room temperature. Magnetic field and frequency dependence room temperature magnetoimpedance are decreased with particles size of the nanoparticles. This behaviour has been explained through the light of classical electrodynamics, which reveals that this effect is depending on the magnetic field and ac signal frequency. Impedance spectroscopy is employed to study the electrical transport properties of the samples considering an equivalent circuit model for the effect of nanometric grain size. The electrical relaxation process of these materials is temperature dependent. Furthermore, ac conductivity curves follow the Jonscher's power law for electrical conduction process of the system through polaronic hopping.