Ferromagnetic-Dielectric Ni0.5Zn0.5Fe1.9O4−δ/PbZr0.52Ti0.48O3 Particulate Composites: Electric, Magnetic, Mechanical, and Electromagnetic Properties (original) (raw)
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Advances in Condensed Matter Physics, (2010) ID 763406
Novel ferromagnetic-dielectric particulate composites of Ni 0.5 Zn 0.5 Fe 1.95 O 4−δ (NZF) and PbZr 0.52 Ti 0.48 O 3 (PZT) were prepared by conventional ceramic method. The presence of two phases in composites was confirmed by XRD technique. The variations of dielectric constant (ε) with frequency in the range of 100 kHz-1 MHz at room temperature and also with temperature at three different frequencies (50 kHz, 100 kHz, and 500 kHz) were studied. Detailed studies on the dielectric properties were done confirming that the magnetoelectric interaction between the constituent phases may result in various anomalies in the dielectric behaviour of the composites. It is proposed that interfaces play an important role in the dielectric properties, causing space charge effects and Maxwell-Wagner relaxation, particularly at low frequencies and high temperatures. The piezoelectric d 33 constant was studied at room temperature, and the d 33 constant value decreased with ferrite content. Magnetic properties like B-H loops traces were studied to understand the saturation magnetic (M s ) and magnetic moment (μ B ) of the present particulate composites. The magnetoelectric (ME) output was measured by varying dc bias magnetic field. A large ME output signal of 2780 mV/cm Oe was observed in the composite having 50% ferrite. The temperature variation of longitudinal modulus (L) and internal friction (Q −1 ) of these particulate composites at 104 kHz was studied in the temperature range 30 • C-420 • C by the composite oscillator technique. Longitudinal modulus showed a sharp minimum, and internal friction exhibits a sharp peak at ferroelectric-paraelectric phase transition. These ferroelectric-dielectric particulate composites were prepared with a view to using them as ME sensors and transducers.
Ceramics International, 2013
Composites having general formula 0.1Ni 0.8 Zn 0.2 Fe 2 O 4-0.9Pb 1−3x/2 Sm x Zr 0.65 Ti 0.35 O 3 with x ¼0, 0.01, 0.02 and 0.03 were synthesized by a conventional solid state reaction route. X-ray diffraction analysis was carried out to confirm the coexistence of individual phases and microstructural study was done by using a scanning electron microscope. Dielectric properties were studied as a function of temperature and frequency. To study ferroelectric and magnetic ordering in composite samples, P-E and M-H hysteresis loops were recorded respectively. Maximum magnetoelectric coupling coefficient of 22.5 mV/cm Oe was observed for sample with x ¼0.03. A significant improvement in dielectric, ferroelectric, piezoelectric and magnetoelectric properties was observed for Sm substitution.
Journal of Alloys and Compounds, 2018
The magnetoelectric composites with the compositions of ferrites & ferroelectrics having the general chemical formula (x) Ni 0.8 Mg 0.2 Fe 2 O 4 + (1-x) BaZr 0.2 Ti 0.8 O 3 (in which x = 0.1, 0.2, 0.3) were synthesized by using double sintering ceramic technique. From XRD, the phase formation of ferrites with cubic structure and ferroelectrics with tetragonal perovskite structure was confirmed through the measurement of XRD. The two phase ME composites have larger saturation magnetization and dielectric constant; it is because of the effect of interfacial strain on BaZr 0.2 Ti 0.8 O 3 ferroelectric phase. Furthermore, the ME response 4.262 mVcm −1 Oe −1 was observed for (30%) Ni 0.8 Mg 0.2 Fe 2 O 4 + (70%) BaZr 0.2 Ti 0. 8O 3 composites at 5.0 kOe applied DC magnetic field; it shows the success of magnetic control of the dielectric response via the mechanical coupling which can be exploited in the future applications of multiferroic composites.
Journal of Materials Science, 2008
This study investigates the variation of magnetoelectric (ME) coefficient as a function of the piezoelectric grain size in the composite system of 0.8 Pb(Zr 0.52 Ti 0.48)O 3-0.2 Ni 0.8 Zn 0.2 Fe 2 O 4. It was found that as the piezoelectric-phase grain size increases the overall resistivity, piezoelectric, dielectric, and ferroelectric property of the composite increases and saturates above 600 nm. Below 200 nm average grain size, piezoelectric and dielectric properties decrease rapidly. The ferroelectric Curie temperature was found to decrease from 377 to 356°C as the average grain size decreases from 830 to 111 nm. ME coefficient of the composite showed a rapid change below grain size of 200 nm and was found to saturate above 600 nm to a value of 155 mV/cm.Oe.
Magneto-dielectric properties of ferrites and ferrite/ferroelectric multiferroic composites
Processing and Application of Ceramics
Ni-Zn ferrites, with the general formula Ni1-xZnxFe2O4 (x = 0.0, 0.3, 0.5, 0.7, 1.0), CoFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 powders were synthesized by auto-combustion method. The composites were prepared by mixing the appropriate amounts of individual phases, pressing and conventional sintering. X-ray analysis, for individual phase and composites, indicated the formation of crystallized structure of NiZnFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 without the presence of secondary phases or any impurities. SEM analyses indicated a formation of uniform grain distribution for ferromagnetic and ferroelectric phases and formation of two types of grains, polygonal and rounded, respectively. Magneto-dielectric effect was exhibited in all samples because of the applied stress occurring due to the piezomagnetic effect and the magnetic field induced the variation of the dielectric constant. For all samples the dielectric constant was higher in applied magnetic field. At the low frequency, the dispersi...
We have carried out the powder x-ray diffraction and dielectric studies on multiferroic particulate composite xNi 0.9 Zn 0.1 Fe 2 O 4 /(1-x)PbZr 0.52 Ti 0.48 O 3 with x=0.15, 0.30, 0.45, 0.60, 0.75 and 0.90 to explore the structural and ferroelectric properties. A conventional double sintering method was used to prepare the xNi 0.9 Zn 0.1 Fe 2 O 4 /(1-x)PbZr 0.52 Ti 0.48 O 3 composites. The structure of one of the component Ni 0.9 Zn 0.1 Fe 2 O 4 is spinel cubic with space group , while the other component PbZr 0.52 Ti 0.48 O 3 is selected around the morphotropic phase boundary region in which the tetragonal and monoclinic phases with space group P4mm and Cm coexist respectively. We have carried out Rietveld refinement of the structure to check the formation of ideal composites with separate ferroelectric and ferrite phases. Even though the structural characterization does not reveal the formation of any new phase due to reaction between the two components of the composite during sintering, the tetragonality of the PbZr 0.52 Ti 0.48 O 3 continuously decreases with increasing the ferrite fraction while the lattice parameter of ferrite phase increases with increasing fraction of the ferroelectric phase. Similarly, the dielectric study reveals clear shift in the ferroelectric to paraelectric phase transition temperature of PbZr 0.52 Ti 0.48 O 3 during composite formation suggesting that part of Ni 2+ , Zn 2+ / Fe 3+ ions are diffusing at the B-site of PbZr 0.52 Ti 0.48 O 3 replacing Ti 4+ , which in turn decreases its transition temperature. Scanning electron micrograph of sintered pellet surface confirms the presence of two types of particle morphology in the particulate composite, corresponding to ferrite and ferroelectric phases.
Ceramics International, 2018
Comparative study of different PZT-based composite materials ((x)PbZr 0.52 Ti 0.48 O 3 + (1-x)CoFe 2 O 4 and (x)PbZr 0.52 Ti 0.48 O 3 +(1-x)Ni 0.7 Zn 0.3 Fe 2 O 4 (x=0.8 and 0.9)) is presented in the frame of structural, dielectric, ferroelectric and magnetic properties. PZT and NZF/CF powders were synthesized by auto combustion technique. The composites were synthesized by mixing the appropriate amount of individual phases using conventional sintering. XRD data indicated the formation of well crystallized structure of PZT and NZF/CF, without the presence of undesirable phases. SEM micrographs revealed a uniform grain distribution of both, ferroelectric and ferromagnetic phases. Non-saturated hysteresis loops are evident in all samples due to the existence of non-ferroelectric ferrite phase. All the samples exhibit typical ferromagnetic hysteresis loop, indicating the presence of the order magnetic structure. Dielectric investigations revealed that ferrites are the main source of charge carriers, which must be of electronic origin. The activation energy of effective electrical resistivity is heavily influenced by the ferroelectric phase.
Ferroelectric and dielectric properties of ferrite-ferroelectric ceramic composites
Journal of Applied Physics, 2013
Particulate composites of ferrite and ferroelectric phases with xNiFe 2 O 4 (NF) and (1 À x)Pb 0.988 (Zr 0.52 Ti 0.48 ) 0.976 Nb 0.024 O 3 (where x ¼ 2, 10, 20, 30, 50, 70, and 100 wt. %) were prepared in situ by sol-gel method. The presence of a diphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric permittivity shows usual dielectric dispersion behavior with increasing frequency due to Maxwell-Wagner interfacial polarization. AC conductivity measurements made in frequency range 1 Hz-1 MHz suggest that the conduction process is due to mixed polaron hopping. The effect of NF phase concentration on the P-E and M-H hysteresis behavior and dielectric properties of the composites was investigated. At low NF concentration a sharp ferro-paraelectric transition peak can be observed at around 360 C while for higher NF concentrations a trend to a diffuse phase transition occurs. All the composite samples exhibit typical ferromagnetic hysteresis loops, indicating the presence of ordered magnetic structure. V C 2013 American Institute of Physics.