Magnetodielectric Coefficient Research Articles

Strong magnetodielectric effect in Bi(La)Fe(Cr)O3 multiferroic nanomaterials

The Bi1-xLaxFe1-yCryO3 (x = 0.00, 0.06; y = 0.00, 0.03, 0.06, 0.09, 0.12) nanomaterials have been synthesized using the simple solvo-thermal technique. The Rietveld refinement of XRD analysis using FullProf Software confirms that all synthesized materials follow rhombohedral perovskite crystal structure of R3C space group. The dielectric and ac conductivity data are analyzed to understand the role of grain and grain boundary contributions. The enhancement of magnetic properties has been observed from SQUID measurement for the co-doped samples at room temperature. Also, a significant improvement in polarization has been observed for the doped nanocompounds from the ferroelectric hysteresis loop. The magneto-dielectric study reveals a large improvement in our co-doped BFO nanomaterials and the value is nearly three times of those reported earlier. The calculated energy storage efficiency for the co-doped samples are found to have as high as 51 %. The sample with x = 0.06 and y = 0.09 with a magneto dielectric coefficient of around 30 % and energy storage efficiency of 35 % is the most suitable for both spintronic and energy storage devices.

Recapitulation of the magnetic and magnetodielectric properties of (1-x)LiNbO3 - (x)La0.9Na0.1MnO3 (x = 0.1, 0.2, 0.3) composites

The present study provides structural, ferroelectric, magnetic, magnetodielectric and the optical properties of the composite (1-x)LiNbO3-(x)La 0.9Na 0.1MnO3 with different values of x (where x = 0.1, 0.2 and 0.3) at room temperature. Ferroelectric phase LiNbO3(LNB) and magnetic phase La 0.9Na 0.1MnO3(LNMO) were synthesized by conventional solid state reaction method. Rietveld X-ray diffraction pattern reveals the structural purity of the synthesized samples. The ferroic and antiferroic nature of the composites were investigated from M-H hysteresis loop, at x = 0.3 shows highest value of saturation magnetization. The reduced ferroelectric nature of the prepared samples was revealed through P-E hysteresis loop measurement with sample x = 0.1 shows highest value of remnant polarization room temperature. Magnetoelectric coupling nature of the composite sample was confirmed through magnetodielectric measurement. Among the studied composites highest value of magnetodielectric percentage (MD%) at 1 kHz is obtained for sample with x = 0.3. Enhanced magnetodielectric coupling coefficient value of 5.5 is achieved for the sample with x = 0.3. Optical properties were examined from UV absorbance analysis technique. On increasing LNMO content, there was a slight decrease in the band gap energy. The enhanced magnetoelectric coupling property of the present synthesized composite paves the way for more room temperature multifunctional materials.

Effect of a magnetic field on the dielectric properties of PLT–BNCFO composites

The main goal of this study is to analyze the magnetic, dielectric and magneto-dielectric characteristics of Pb1− x La x Ti1− x O3 (PLT)–(Ba1−3 x Nd2 x )4Co2Fe36O60 (BNCFO) (where x = 0.25) composite materials T1–T3 sintered at various temperatures (1100, 1200 and 1300°C, respectively). An X-ray diffraction investigation was performed in order to pinpoint the creation of a U-type hexaferrite phase. Scanning electron microscopy micrographs reveal that sample T2 reached the maximum value of grain size and the largest experimental density value of 6.14 g/cm3 due to the intensified grain growth of the composite material. The magnetic investigations further indicate that sample T2 achieved the highest remnant magnetization, measuring 1.550 emu/g, revealing the suitability of the sintering temperature. The magneto-dielectric investigations demonstrate the presence of multiferroicity in all samples and show that sample T2 exhibits the highest magneto-dielectric response of 41.99 at 1.2 T and a magneto-dielectric coefficient (γ) of around 0.7609 g2/emu2. Numerous metrics, including Nyquist plots, impedance, electrical modulus, dielectric constant and conductivity, were carefully examined in order to determine the electrical properties of the proposed sample. It was found that sample T2 produced enhanced results and had the right temperature for the substance to develop.

Ni-Zn-Cu-ferrite-PVDF multiphase nanocomposite material for the application of multiferroics and improved EMI shielding effectiveness

In search of an effective multifunctional laminated nanocomposite material useful for microwave absorption and multiferroic applications, the nanoparticles of Ni-Zn-Cu-ferrite (NZCF) were successfully encapsulated inside the matrix of poly(vinylidene fluoride) (PVDF). The crystallographic phases of bare NZCF, PVDF and NZCF-PVDF nanocomposite films were confirmed by X-ray diffraction measurement. Field emission scanning electron microscopy (FESEM) of NZCF-PVDF nanocomposite films reveals the presence of PVDF matrix all around the surface of the NZCF nanoparticles. The static magnetic properties were measured for both bare NZCF and NZCF-PVDF and different magnetic information were extracted from the study of magnetic measurement. The substantial magnetic responses with comparatively large magnetizations of 2.64 and 13.52 emu/g for S1P20 and S2P20 nanocomposite films respectively have been obtained. Dielectric response study of NZCF-PVDF nanocomposite films was estimated as a function of frequency and temperature. Also, the enhancement of the dielectric constant as a function of temperature with a proper signature of ferroelectric to paraelectric transition was observed for NZCF-PVDF nanocomposite films. This high dielectric constant of NZCF-PVDF is found due to the formation of NZCF-PVDF interfaces inside the resultant nanocomposite films. Ferroelectric hysteresis loops of NZCF-PVDF nanocomposite films were observed at 100 Hz which confirms the presence of ferroelectric ordering of the resultant nanocomposite films. Magneto-dielectric (MD) coefficient of NZCF-PVDF nanocomposite films is observed at room temperature and it confirms the presence of significant interactions between the magnetic and ferroelectric order parameters at the interfaces inside the nanocomposite materials. Magneto-dielectric (MD) coefficient of NZCF-PVDF nanocomposite films is observed at room temperature with a maximum MD (%) variation of S1P20 is 30.08 at frequency 1 MHz for an external magnetic field of 1000 Oe. It also suggests the onset of multiferroic property of NZCF-PVDF nanocomposite films. Shielding effectiveness study of NZCF-PVDF nanocomposite films was conducted within the frequency range of 8–18 GHz and a very high value of total shielding effectiveness with large contribution of microwave absorption loss was found. Shielding effectiveness study of NZCF-PVDF nanocomposite films was conducted within the frequency range of 8–18 GHz and a very high value of total shielding effectiveness (SET) ∼ -79 dB at ∼ 12.64 GHz for S2P10 nanocomposite film with large contribution of microwave absorption loss (SEA) ∼ -51 dB at ∼ 12.64 GHz was found. These novel properties of unique NZCF-PVDF nanocomposite films are very much interesting for the applications in high frequency magneto-dielectric device applications.

Structural, ferroelectric, ferromagnetic and magnetodielectric properties of lead free K0.5Na0.5NbO3-Ni0.5Zn0.5Fe2O4 based composites

Utilizing the conventional solid state route, the fabrication of multiferroic composites of (1-x)K0.5Na0.5NbO3-xNi0.5Zn0.5Fe2O4; x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1.0 have been carried out in the present research work. XRD, SEM and EDS analysis shows the successful formation of composites. Whereas, P–E and M−H studies indicate their multiferroic behavior at room temperature. The dielectric properties have been carried out to know about the dielectric constant and loss in the composites. Further, the estimation of magnetoelectric coupling effect (ME) in composites has been done by measuring the magnetodielectric coefficient (MD), which is found to be highest ∼ 17 % and corresponding ME value has been calculated (88 mV/cm.Oe) for x = 0.2 composite.

Magnetoelectric effect generated through electron transfer from organic radical to metal ion.

Magnetoelectric (ME) materials induced by electron transfer are extremely rare. Electron transfer in these materials invariably occurs between the metal ions. In contrast, ME properties induced by electron transfer from an organic radical to a metal ion have never been observed. Here, we report the ME coupling effect in a mononuclear molecule-based compound [(CH3)3NCH2CH2Br][Fe(Cl2An)2(H2O)2] (1) [Cl2An=chloranilate, (CH3)3NCH2CH2Br+ = (2-bromoethyl)trimethylammonium]. Investigation of the mechanism revealed that the ME coupling effect is realized through electron transfer from the Cl2An to the Fe ion. Measurement of the magnetodielectric (MD) coefficient of 1 indicated a positive MD of up to ∼12% at 103.0Hz and 370K, which is very different from that of ME materials with conventional electron transfer for which the MD is generally negative. Thus, the current work not only presents a novel ME coupling mechanism, but also opens a new route to the synthesis of ME coupling materials.

Magneto-transport and magneto-dielectric anomalies in Co doped iron oxide thin films – Microwave assisted sol-gel route

Use of microwave (MW) energy as an alternate to high temperature treatment during material synthesis is gaining much attention as it offers the advantages of being faster and economical than other heating methods. A comprehensive study of structure, magnetization, and polarization behaviour of Cobalt (Co) doped Fe3O4 thin films, prepared by means of microwave assisted sol–gel method is performed. Co doped (0-10 wt%) sols are prepared after irradiating them at MW power of 1000 W. Phase analysis is confirmed using XRD where Fe3O4 phase persisted with Co concentrations of 0-6 wt%. Higher concentration results in the appearance of cobalt oxide phase. Magnetic and transport properties are strongly affected by the presence of Co ions. Co doped Fe3O4 films show anisotropic behaviour with high saturation magnetization obtained for 6 wt% Co doped Fe3O4 thin films, i.e. ∼ 125 emu/g. Verwey transition is observed for thin films with low dopant concentration while no sharp transition in magnetization behaviour is observed for higher dopant concentration. High frequency anomaly in dielectric analysis is observed at high frequencies for Co doped Fe3O4 thin films. Negative values of magneto-dielectric coefficient show coupling of magnetic and dielectric behaviour at room temperature.

Immense Magnetodielectric Effect in Eu2O3-Mesoporous Silica Nanocomposites

Nanodimentional Eu 2 O 3 was developed inside the channels of silica with mesoporus structure, which have5 nm pore diameter. At room temperature, such nanocomposite showed a large magnetodielectric coefficient of around 70% upon application of magnetic field of 1 Tesla at a frequency 1 kHz. The dielectric loss was quite low in spite of the fact that Eu 2 O 3 is conducting in nature. This was achieved because of a scarcelydispensed Eu 2 O 3 species inside silica, which is highly resistive in nature. This method of nanocomposite formation gives rise to the fabrication of devices with high magnetodielectric coefficients.

Study of dielectric and magnetodielectric behavior of flexible PVA-NiNdxFe2-X O4 film for EMI shielding application

We have reported dielectric and magnetocaloric effects in flexible Neodymium (Nd) doped nickel ferrite (NiNdxFe2-xO4) - polyvinyl-alcohol nanocomposite films. The samples are characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and broadband dielectric spectroscopy. The dielectric permittivity is enhanced in the composite for a particular filler concentration. The magnetic entropy change decreases by higher doping in the polymer chain. The magnetodielectric coefficient is enhanced in higher frequency and with the rise in doping concentration. The observed skin depth value of the polymer nanocomposite is lower than the film's thickness which is suitable for electromagnetic shielding.

Microstructure, magnetodielectric and multiferroic properties in PVDF-based sandwich-structured composites

The multiferroic thin films are promising candidates for applications in magnetic sensors, spintronics, information memory, and other multifunctional devices. In this work, BaTiO3-PVDF/CoFe2O4-PVDF/BaTiO3-PVDF sandwich-structured composites were designed and fabricated by a tape-casting method. The microstructure, dielectric, ferroelectric, magnetic and magnetodielectric properties were systematically investigated. An enhanced ferroelectricity is observed for the maximum polarization (Pmax~1.656 μC/cm2) and the high dielectric constant (εr) of 22 as well as a low dielectric loss for all BaTiO3 filler loading, much better than that of the pure PVDF matrix (εr∼8.26). A recoverable energy density of 0.648 J/cm3 is achieved at an electric field 950 kV/cm, along with a high efficiency (η∼71.0 %). The observed typical magnetic hysteresis loop reveals the presence of long-range ferromagnetic ordering in composites, accompanied by the significant magnetic properties with saturation magnetization (MS~0.507 emu/g), and coercivity (HC~2.3 kOe). Additionally, the response of the dielectric performance under the applied magnetic fields is obvious at RT, i.e., a large negative magnetodielectric coefficient of 2.85 % is obtained at a low magnetic field of 2 kOe, and is up to 6.53 % at 6 kOe for 5 vol% BaTiO3. Ultimately, it is anticipated that this work may provide an efficient method to develop flexible multiferroic composite for multifunctional devices.

Crystal structure and magnetoelectric properties of CrFeO3-doped BaZr0.1Ti0.9O3 multiferroic ceramics

Chromium ferrite-doped barium zirconate titanate multiferroic materials in (1-x)BaZr0.1Ti0.9O3 – (x)CrFeO3; BZT-CF) system, when x = 0, 2, 4, 6, 8 and 10 mol%, were prepared by the solid-state reaction technique. Phase formation, lattice parameter, and electronic state of materials were characterized by x-ray diffraction (XRD) and x-ray absorption near-edge spectroscopy (XANES) techniques. It was found that the undoped BZT ceramic showed a single tetragonal phase without the secondary phase. However, CF-doped BZT ceramic at 2–10 mol% reveals that the tetragonal phase was changed to the orthorhombic phase. Lattice parameter and dislocation density have increased with increasing CrFeO3 content, representing the crystal structure's imperfection in interesting material. The magnetic and magnetoelectric of materials were characterized by the vibrating sample magnetometer (VSM) technique. It was found that all-ceramic exhibits a paramagnetic behavior. However, all doped ceramics showed a magnetic field response value better than undoped, with a maximum magnetodielectric coefficient (ME) of 18.3 × 10−3 at 2 mol% of CF-doped.

Lead-Free Aurivillius Phase Bi2LaNb1.5Mn0.5O9: Structure, Ferroelectric, Magnetic, and Magnetodielectric Effects.

Aurivillius phase Bi2LaNb1.5Mn0.5O9, derived from ferroelectric PbBi2Nb2O9 by simultaneous substitution of the A-site and B-site cations, was synthesized using a molten-salt method. Here, we discuss the structure-property relationships in detail. X-ray and neutron diffraction show that Bi2LaNb1.5Mn0.5O9 adopts an A21am orthorhombic crystal structure. Rietveld refinement analysis, supported by Raman spectroscopy, indicates that the Bi3+ ions occupy the bismuth oxide blocks, La3+ ions occupy the perovskite A-site, and Nb5+/Mn3+ ions occupy the perovskite B-site. Ferroelectric ordering takes place at 535 K, which coexists with local ferromagnetic order below 65 K. The cation disorder on the B-site results in relaxor-ferroelectric behavior, and the short-range ferromagnetic order can be attributed to Mn3+/Mn4+ double-exchange. Magnetodielectric coupling measured at 5 K and 100 kHz in a field of 5 T suggests the existence of intrinsic spin-lattice coupling with a magnetodielectric coefficient of 0.20%. These findings will provide significant impetus for further research into potential devices based on the magnetodielectric effect in Aurivillius materials.

Self-biased characteristics of NZCF/BCZT layered magnetoelectric composites: A novel coupling paradigm in magnetoelectricity

Here, we investigate room temperature magnetoelectric (ME) behavior of ferroelectric Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) and ferrimagnetic Ni0.75Zn0.20Co0.05Fe2O4 (NZCF) layered composites. The ferroelectric ceramics (thickness, t, ∼0.6, 0.8, and 1.0 mm) are stacked at magnetic specimen of fixed t ∼ 1 mm, coupled with conducting silver epoxy. The phase formation, surface morphology, dielectric, magnetic, magnetoelectric and magnetodielectric characteristics of bilayer composites have been studied in the present work. The maximum value of magnetoelectric (ME) coupling coefficient (αME) is found to be 70, 90, and 110 mVcm−1Oe−1 for composite having ferroelectric layer thickness t ∼ 1, 0.8, and 0.6 mm, respectively. More importantly, αME(H→0) remains finite for composite (t ∼ 0.8, and 0.6 mm) in zero magnetic field, which is a clear evidence of self-biasing phenomenon in NZCF/BCZT layered composite. For closer insight about underlying mechanism, we estimate magnetodielectric (MD) coefficient for the layered composite. The MD coefficient is found to be significantly high ∼6.32% for the thickness 0.6 mm. MD% vs magnetic field, H, curves exhibit steeper field dependence in low field region and for H≥2kOe MD possess saturation characteristics. The high saturation characteristics suggest that the magnetoelectricity in layered composite is driven by magnetostriction mechanism and causes robust ME coupling. Further, we obtain electrical signal ∼143 mV with the Hdc ∼250 Oe, as a consequence of interplaying nature of magneto(striction)- piezo(electricity). Such a sizeable response will improve the underlying intimacy between technology and practical application. The study reveals that the pellet based layered composites may be a proven strategy for the realization of self-biased ME devices.

Effect of Ni Substitution on Structural, Dielectric, and Ferroelectric Properties and Variation in Magnetocapacitance of Single-Phase Ba0.7Pb0.3TiO3 Ceramic

The present study demonstrates the influence of Ni substitution on the structural, dielectric, and ferroelectric properties of single-phase Pb-doped BaTiO3, that is, Ba0.7Pb0.3TiO3 (BPT) ceramic, and variations in the magnetocapacitance. The hydroxide co-precipitation method was employed to fabricate single-phase Pb-doped BaTiO3 and Ni-substituted Ba0.7Pb0.3TiO3, as Ba0.7Pb0.3TiO3-(x)Ni for x = 0.05, 0.1, and 0.15. Rietveld refinement reflects the single-phase tetragonal crystal structure of pure Ba0.7Pb0.3TiO3 and at higher Ni concentrations, the detection of rhombohedral crystal symmetry of the NiO phase confirms the biphasic structure of the composite. The ferroelectric-paraelectric transition temperature decreased from 274 °C for pure Ba0.7Pb0.3TiO3 to 162 °C for the composite with a higher Ni concentration of x = 0.15. A drastic change in the typical ferroelectric (P-E) loop of Ba0.7Pb0.3TiO3 was observed with the substitution of Ni. The composite with a higher concentration had the highest value of the magnetodielectric coupling coefficient, MD (%) = −2.86. This study reflects an easy and useful approach to achieve two-order parameter coupling with doping of acceptor ions in the ferroelectric phase. This kind of material substantially plays a vital role in the advanced electromagnetic devices for futuristic applications.

Магнитодиэлектрические свойства композиционных феррит-пьезоэлектрических материалов.

Ceramic composite materials based on compounds of lead zirconate-titanate and cobalt ferrite with different content of the initial components mass fraction have been synthesized. Using a complex of physicochemical methods, the microstructure and magnetodielectric properties of the synthesized ceramics have been studied. The resulting frequency dependences of the magneto-dielectric coefficient for the composite system (1-x)PZT + xCF(0.0 ≤ x ≤ 0.5) in an external magnetic field have a resonance form in the entire concentration range investigated. The largest changes in the value of the complex permittivity are observed for the sample with the composition of 0.6PZT + 0.4CF.

The effects of indium doping on the electrical, magnetic, and magnetodielectric properties of M-type strontium hexaferrites

A series of indium-doped hexaferrite ceremics with composition of SrInxFe12-xO19 (x = 0, 1.8, 2.4 and 3.0) were synthesized by a solid-state reaction method. The samples have a single-phase magneto-plumbite structure, and their lattice parameters a and c gradually decrease with the doping indium amount. The indium doping can reduce the ceramic pores. The dielectric constant, dielectric loss, saturation magentization and coercivity also decrease with the indium concentration. The dielectric change with temperature under different frequencies and magnetic fields reveals that the magnetic field has a certain manipulation on the dielectric parameter. Indium doping induces the non-collinear magnetic structure, causing a magnetodielectric effect. The influence of the magnetic field on the magnetodielectric coefficient shows that the magnetodielectric coefficient changes from positive to negative for SrInxFe12-xO19 with x = 0.0, 2.4 and 3.0, while keeps negative in the whole temperature range for SrIn1.8Fe10.2O19. At the same time, the positive and negative magnetodielectric transition temperature is different for the samples with different doping amounts. The transition temperature of SrFe12O19 is between 50 K and 75 K, while that of SrInxFe12-xO19 (x = 2.4–3.0) is between 25 and 50 K. In addition, SrIn2.4Fe9.6O19 enjoys the magnetodielectric effect with remarkable twisted-butterfly loop at room temperature, which is an intrinsic effect confirmed by the fact that the magnetodielectric coefficient is invariable with frequency. Our results provide a helpful research basis for the magnetodielectric materials.

Ferroelectric and magnetic domain mapping of magneto-dielectric Ce doped BiFeO3 thin films

Co-existent ferroelectric and magnetic ordering at room temperature in multiferroics has generated significant interest for potential applications in low-power sensors, transducers, and memory devices. Despite tremendous efforts centered on site-substitution in BiFeO3 to attain enhanced functionality, local probing of multiferroic domain dynamics with dopant concentration remains overlooked. Here we report a detailed investigation on ferroelectric and magnetic domain mapping of Bi1−XCeXFeO3; 0 ≤ X ≤ 0.2 (BCFOX) thin films and discussed concentration-dependent behavior of piezo-response switching, piezo-actuation butterfly-loop and phase-hysteresis, and magneto-dielectric coupling. Large piezo-response amplitude change of 30 mV and near to complete phase reversal of ~150° together with homogeneous magnetic domain distribution and an enhanced magneto-dielectric coupling coefficient of 2.15% at 0.3 T unveils improved ferroelectric ordering in polycrystalline BCFO0.12 thin film. We believe, our findings will develop a comprehensive understanding of sensitive force microscopy technique for the custom-made advancement of BiFeO3 based multiferroic family.

Ferroelectric and magnetic properties of 0.5BiFeO3-0.5PbFe0.5Nb0.5O3 ceramics

The microstructure, dielectric and magnetic characteristics, and magnetodielectric effect in multiferroic 0.5BiFeO3-0.5PbFe0.5Nb0.5O3 ceramics are studied. It is determined that 0.5BiFeO3-5PbFe0.5Nb0.5O3 belongs to the relaxor ferroelectrics group by the nature of changes in the real and imaginary parts of the complex permittivity at T = 30–300 °C. It is discovered that the material is in magnetic phase at room temperature. The magnetodielectric effect (positive and negative) is detected at T < 200°С. The maximum value of magnetodielectric coefficient is 1.64%. The reasons for the identified regularities are discussed.

0.5BiFeO3–0.5PbFe0.5Nb0.5O3 Multiferroic Ceramic: Structure, Dielectric and Magnetodielectric Properties

The structure, dielectric characteristics, and magnetoelectric effect of a 0.5BiFeO3–0.5PbFe0.5Nb0.5O3 multiferroic ceramics are studied. We found that the ceramics is pure and has a structure similar to that of cubic one with a = 3.999(5) A at room temperature, which is retained within 20–600°C. We showed that the 0.5BiFeO3–0.5PbFe0.5Nb0.5O3 solid solution possesses both ferroelectric and antiferromagnetic properties at T < 200°C. The magneto-dielectric coefficient and the magneto-dielectric one of dielectric losses in the material are –0.4 and –0.5%, respectively, at room temperature under constant magnetic field of 0.86 T.

Effect of Mn doping on magnetodielectric properties of polycrystalline BiFeO3 ceramics

This report reveals the room temperature magnetodielectric effect of polycrystalline BiFe0.8Mn0.2O3 ceramics. Structural analysis shows that the additional phases of BiFe0.8Mn0.2O3 are suppressed and compared with bare BiFeO3. The difference in dissociation energies between Mn–O and Bi–O bonds traps the motion of oxygen ions and reduces the grain size of BiFe0.8Mn0.2O3. Mn-doped BiFeO3 samples exhibit a weak ferromagnetic response because of the effect of Mn in the Fe site which uncurls the spiral spin ordering by altering the canting angle. Additionally, Bi vacancies give rise to charge compensating oxidation of Mn3+/ Mn4+ which causes the ferromagnetic weaker. BiFe0.8Mn0.2O3 shows an improved dielectric permittivity compared to BiFe0.9Mn0.1O3 and BiFeO3 respectively. The magnetodielectric coupling coefficient of BiFe0.8Mn0.2O3 ceramic at 6 kOe and 1 MHz is determined to be 4.64%.