BaTiO3 Content Research Articles

Local structure and evolution of phase transformation in Bi0.4871Na0.4871La0.0172TiO3–BaTiO3 materials

Lead-free bismuth sodium lanthanum titanate and barium titanate (Bi0.4871Na0.4871La0.0172TiO3–BaTiO3; ((1-x)BNLT-xBT) ceramic system, where x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10, were synthesized by a modified two-step mixed oxide method. The global structure was investigated by X-ray diffraction (XRD), while the local structure was elucidated by X-ray absorption near edge structure (XANES). The XRD results indicated a rhombohedral perovskite crystal structure for x < 0.04 and a tetragonal perovskite crystal structure for x ≥ 0.04. The Ti K-edge XANES spectra indicated a change in local structure around the Ti atom, which corresponds to an evolution of phase transition from rhombohedral to tetragonal structure in BNLT-BT system with increasing BaTiO3 content. A comparison between the measured and simulated spectra was obtained and discussed in details.

Enhancement of dielectric properties and energy storage performance in 3Y‐TZP ceramics with BaTiO3 additives

AbstractWith the fast charge‐discharge speed and ultrahigh power density, electrostatic energy storage materials offer great potential in the applications for pulsed power systems. As a very important member of structural ceramics, 3Y‐TZP (3 mol% Y2O3 doped tetragonal zirconia polycrystals) has shown extraordinary mechanical properties. However, the research on their energy storage performance is still lacking. Herein, a ferroelectric phase, BaTiO3 (BT), was introduced and demonstrated to improve the dielectric properties and energy storage performance of 3Y‐TZP ceramic matrix via the conventional solid‐state reaction method. With increasing the BT content from 0 to 15 mol%, the permittivity of the composite ceramics could be effectively increased from 40.2 to 64.1 measured at 1 kHz. Simultaneously, the dielectric loss could be effectively decreased by depressing the response of charged defects, which was further interpreted by the thermally stimulated depolarization current technique. Meanwhile, the breakdown strength showed a typical increase‐then‐decrease trend with increasing BT content, and reached their maximum values when doped with 7 mol% BT. Together with the enhancement of dielectric properties, the 7 mol% BT‐doped 3Y‐TZP ceramics exhibited a maximum energy storage density of 0.42 J/cm3, which was approximately 150% larger than that of the pure 3Y‐TZP ceramics.

Effect of molar ratio on the microstructure, dielectric and electromagnetic properties of BaTiO3/CoFe2O4 ceramic

BaTiO3/CoFe2O4 (BTO/CFO) composite ceramics were synthesized by conventional solid-phase method, and the effects of different BaTiO3 (BTO) and CoFe2O4 (CFO) contents on the microstructure, magnetoelectric properties were systematically studied. X-rays showed that ferroelectric and ferromagnetic phases can coexist without chemical reaction. The dielectric constant decreased with the decrease of the molar ratio of BTO, and the dielectric constant increased with the increasing of temperature. The dielectric loss decreased first and then increased and finally decreased as a function of frequency, and the dielectric loss increased with the increase of temperature. The composite with the molar ratio of BTO/CFO (3:1) demonstrated better ferroelectric properties that remnant polarization is 0.82 μC cm−2 and the coercive electric field is 10.23 kV cm−1. The best magnetic property was shown in BTO/CFO (1:3).

Fabrication of BaTiO3 ceramic filler incorporated PVC-PEMA based blend nanocomposite gel polymer electrolytes for Li ion battery applications

In spite of promising electrochemical characteristics of the Gel polymer electrolytes (GPEs) it’s applicability in Li ion cells are limited due to their low mechanical strength and poor interfacial stability. Herein, we propose composite polymer electrolyte (CPE) fabricated by dispersing hydrothermally derived BaTiO3 (BT) nanoparticle in PVC (5)-PEMA (25)-EC/DMC (67)-LiClO4 (8). We show that the proposed CPE prepared by solution casting technique exhibits enhanced mechanical strength and interfacial stability. The effects of concentration (2.5–10 wt%) of nano BT on GPEs were investigated by various spectroscopic and electro-analytic techniques. Remarkably, 2.5 wt% nano BT incorporated CPE have a higher ionic conductivity and thermal stability compared to ceramic free GPE. Besides, it also has better interfacial stability and display high Li transference number with extended electrochemical stability window. The outstanding electrochemical performance of CPE is due to presence of nano BT that facilitates charge transport behavior and modifies the crystallinity leading to high Li ion transport in CPE. GPE with 2.5 wt% nano BT showed the best electrochemical performance and may be a promising reliable CPE cum separator for Li ion battery (LiBs) applications.

Characterizations of P(VDF-HFP)-BaTiO3 nanocomposite films fabricated by a spin-coating process

Abstract In this work, free-standing and flexible polymer-ceramic nanocomposite films were fabricated by a spin-coating process using poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] as matrix and BaTiO3 (BTO) nanoparticles as filler. The relationships between the properties and compositions were systematically investigated. It is experimentally found that the crystallinity and the size of crystals of the P(VDF-HFP) matrix decreases with increasing BTO content. The dielectric responses of the polymer used as matrix were determined by four dielectric processes. Both the temperature and frequency dependences of the dielectric responses obtained in the composite films are mainly determined by the polymer matrix, and the influences of the ceramic filler on the four dielectric processes of the polymer matrix were discussed.

Significantly Enhanced Performance of Triboelectric Nanogenerator by Incorporating BaTiO3 Nanoparticles in Poly(vinylidene fluoride) Film

Triboelectric nanogenerators (TENGs) have received significant attention in recent years due to their renewable and sustainable properties. They convert mechanical energy into electric energy through contact and separation of two dissimilar materials. Many methods have been developed to improve the performance of TENGs, but little attention has been paid to use nanoparticles such as BaTiO3 (BTO) with high dielectric constant for enhancing the performance. This paper reports the achievement of significant performance enhancement of poly(vinylidene fluoride) (PVDF)/polyamide‐6 (PA6) TENGs by incorporating BTO nanoparticles into the PVDF film. The PVDF‐BTO/PA6 TENG with 10 wt% BTO nanoparticles shows the best results with a peak voltage and charge density up to 900 V and 34.4 μC m−2 at contact frequency of 5 Hz when the contact force and the spacer distance are 180 N and 100 mm, which are much higher than 384 V and 26.4 μC m−2 of the PVDF/PA6 TENG without incorporating BTO nanoparticles. Further increase in the BTO concentration deteriorates the output performance of the TENGs. Detailed investigations on the piezo‐response and permittivity of the PVDF‐BTO films show that the increased piezoelectric constant and permittivity are responsible for the significantly enhanced performance of the TENGs. A mathematical model has been developed to describe the output voltages of the TENG as a function of thickness of the PVDF‐BTO film.

Magnetic properties of sintered CoFe2O4–BaTiO3 particulate magnetoelectric composites

Abstract The magnetic properties of sintered particulate magnetoelectric CoFe2O4−BaTiO3 composites have been studied. The particulate composites are sintered in the temperature range 1000–1300 °C, for a short duration of 10 min. The magnetic transition temperature (Tc) of CoFe2O4 is found to decrease with increasing the sintering temperature and sintering time, as well as on increasing the BaTiO3 content in the composites. Similarly, a reduced saturation magnetization at room temperature, compared to that expected for the CoFe2O4 content, is also observed. Powder X-ray diffraction studies showed the presence of the impurity phase related to the hexagonal ferrite BaFe12O19 in all the composites. Ba2Fe2Ti4O13 is observed as a second impurity phase in the BaTiO3−rich composites. The present studies suggest that the composition of the piezomagnetic (CoFe2O4) phase in the CoFe2O4−BaTiO3 magnetoelectric composite is affected during the sintering process.

Crystal Structure and Multiferroic Behaviors of Solid Solution (1-y)BiFe&lt;sub&gt;(1-x)&lt;/sub&gt;Mn&lt;sub&gt;x&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-yBaTiO&lt;sub&gt;3&lt;/sub&gt;

It is expected that BiFeO3-based materials will have both ferroelectricity and ferromagnetism. (1-y)BiFe(1-x)MnxO3-yBaTiO3 system was prepared using solid state reaction method. The goal of this study is to uncover the impacts of Mn doping and BaTiO3 content on the crystal structure, magnetism and ferroelectric properties. By forming a solid solution with BaTiO3, stable perovskite BiFeO3 was achieved. The rhombohedrally distorted (1-y)BiFe(1-x)MnxO3-yBaTiO3 showed weak ferromagnetism due to the composition of BaTiO3 and the doping of Mn ion. 0.8BiFe0.9Mn0.1O3-0.2BaTiO3 and 0.7BiFe0.9Mn0.1O3-0.3BaTiO3 ceramics exhibited typical P-E hysteresis loops.

Microstructures and piezoelectric performance of eco-friendly composite films based on nanocellulose and barium titanate nanoparticle

Eco-friendly nanocellulose-based composite films including different barium titanate (BaTiO3) nanoparticle contents were fabricated by an efficient aqueous suspension casting and following electric poling. The microstructures, dielectric/electrical property, and piezoelectric performance of the nanocellulose composite films were investigated as a function of the BaTiO3 content. The electron microscopic images demonstrated that the BaTiO3 nanoparticles were uniformly dispersed in the nanocellulose-based composite films. The X-ray diffraction results confirmed the presence of piezoelectric tetragonal BaTiO3 nanoparticles in the nanocellulose matrix with cellulose II phase. The dielectric constant and loss tangent of the composite films were found to increase and decrease with increasing the BaTiO3 content, respectively, which is favorable to achieve high piezoelectric outputs. On the other hand, the piezoelectric performance of the composite films increased with the BaTiO3 content up to 40 wt% and it decreased for the composites with 50–60 wt% BaTiO3, which results from the trade-off effect between the piezoelectric performance and the mechanical stiffness of BaTiO3 nanoparticle. Accordingly, the nanocellulose composite film with 40 wt% BaTiO3 was found to attain maximum piezoelectric outputs of voltage of ∼2.86 V, current of ∼262.4 nA, and electric power of ∼378.2 nW under a relatively low compressional stress of 5 kPa, which was high enough to charge microcapacitors after rectification.

Preparation and characterization of BaCo0.5Nb0.5O3-based new high temperature NTC sensitive ceramics

A new type of high temperature NTC thermal sensitive ceramics BaCoxNbxTi(1−2x)O3 (BCNT) was synthesized via a solid-state reaction process. The as-prepared ceramics were obtained by sintering at 1300 °C for 1 h in air. According to the XRD and SEM analysis, BCNT form a solid solution with cubic phase, and the content of BaTiO3 (BT) has insignificant influence on the mean grain size of the ceramics. The BaCo0.5Nb0.5O3 (BCN) based materials show typical NTC effect in the whole temperature measuring range (25–500 °C). The room temperature resistivity (ρ25), thermal constant (B25/85) and activation energy (Ea) increase monotonously with the increase of BT content. The TG-DSC results show that there is no phase transition in the temperature range from 25 to 1000 °C, which indicate that the structure of the BCN-based ceramics is stable at high temperature.

Synthesis and Characterization of BaTiO₃/Polypyrrole Composites with Exceptional Dielectric Behaviour.

Higher concentrations of ceramic fillers induce brittleness in the ceramic/polymer hybrids which restrict their applications to limited fields especially when such hybrids are prepared for their use as dielectrics. We have synthesized and characterized different BaTiO3-polypyrrole (PPy) composites by changing the concentration of BaTiO3 from 1% by weight of PPy taken to 5 wt % to explore its effect on the dielectric parameters of the final product and found that the BaTiO3-polypyrrole composite with weight ratio of 0.05:1 exhibited highest dielectric constant, lowest dielectric loss and thermally most stable. All the composites were prepared using in-situ polymerization of pyrrole in an aqueous dispersion of low content of BaTiO3 in the presence of small amount of Hydrochloric acid. These composites were characterized for their microstructure and crystallinity by X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) while thermal stability by thermo gravimetric (TGA) analysis. An impedance analyser (LCR meter) was utilized to investigate the dielectric parameters. FT-IR data confirmed the presence of the two phases and their interaction, inferred from the shifting of normal PPy peaks. The data obtained from XRD confirmed the presence of crystallites of 2.8 to 5 nm with dominant crystallinity of the filler, TGA analysis (25 to 600 °C) confirmed the higher thermal stability induced on successive addition of the filler into the prepared composites as compared to that of pure PPy in a wide temperature range which is unusual for such a low % age addition of the filler. The SEM analysis together with XRD results reveal that the successive introduction of BaTiO3 particles produced crystallites of 2 to 5 nm size which bonded together and changed the hemispherical shaped larger grains of the matrix to regular shaped smaller grains. The dielectric constant of the composites was enhanced with filler contents from 178 to 522 at 1 MHz for 1 wt % and 5 wt % BaTiO3 respectively. It was concluded that the introduction of BaTiO3 into the polymer matrix with this new procedure has greatly affected the polymerization process, thermal stability, morphology and dielectric properties of the host matrix and has resulted in a novel series of the composites which may have broad applications.

Non suitability of silver ion conducting polymer electrolytes based on chitosan mediated by barium titanate (BaTiO3) for electrochemical device applications

In this study, we report the non-suitability of silver ion conducting polymer electrolytes mediated by barium titanate (BaTiO3) for electrochemical device applications. Various amounts of BaTiO3 fillers have been added to chitosan: silver triflate (CS:AgTf) solution to prepare polymer composites. Electrical impedance spectroscopy (EIS) has been used to characterize electrical properties of the samples. Charge transfer resistance has been correctly estimated for the samples using electrical equivalent circuit (EEC) model. At 3 and 5 wt % of BaTiO3 filler, the charge transfer resistance was found to increase and diameter of the impedance plots are shown to be widened due to the increase of grain boundaries. The dielectric constant is also observed to decrease with the increase of BaTiO3 concentration. DC conductivities for the composite samples are estimated from AC conductivity spectra. The DC conductivity was found to decrease from 4.7 × 10−7 S/cm to 5.4 × 10−9 S/cm for CS:AgTf system incorporated with BaTiO3 filler. Such decrease has revealed that the electrolytes are not suitable for electrochemical device applications. Shifting of relaxation peaks of imaginary part of electric modulus towards low frequency side has indicated the increase of relaxation time and hence the decrease in DC conductivity. The relaxation processes are also studied using Argand plots. The existence of metallic silver nanoparticles has been examined via ultraviolet–visible (UV–Vis) spectroscopy. The UV–Vis spectra showed that surface plasmon resonance (SPR) peaks are broadened and increased in their intensity as the BaTiO3 concentration increased from 1 to 3 wt %. This implied that the reduction rate of silver ions to silver nanoparticles is increased. Moreover, disappearance of SPR peak was found for the BaTiO3 concentration of 5 wt %, revealing the bulk formation of silver metals. Transmission electron microscopy (TEM) images were obtained for the samples, in which the formation of bulk metallic sizes of silvers was found to be obvious. This growth of bulk silver metals at high BaTiO3 concentration was further supported by optical and scanning electron microscopy (SEM) techniques. The distribution of white specs due to silver nanoparticles on the surface of chitosan-silver triflate solid film was investigated. Large white sheets were appeared on the surface of CS:AgTf incorporated with 5 wt% BaTiO3 and related to the huge amount of aggregated metallic silver particles. Sharp intense peaks due to metallic silver particles and weak peaks due to BaTiO3 fillers have been observed in the analyses of energy dispersive X-ray (EDX) spectra.

Study on properties of barium titanate/polyethersulfone dielectric composites prepared by physical dispersion method

Composite materials applied to capacitors with high dielectric constant, low dielectric loss and outstanding thermal stability are concerned widely in the field of dielectrics. So committed to the development of dielectric materials with excellent performance is the key factor. In this work, the barium titanate/polyether sulfone (BaTiO3/PES) composite films were prepared by a physical dispersion technology, which utilized a ball milling machine by high-speed circulation, scattered the PES solution contained BaTiO3 in deionized water with the aid of a surfactant. Then, the BaTiO3/PES composite films were obtained through a series of operations, containing reclaimed organic solvent, washed with deionized water, filtered, dried and hot pressed. The morphology of the BaTiO3/PES emulsion was investigated by TEM and SEM. The results showed that the BaTiO3 particles were covered in the PES resin matrix homogeneously. For 50 wt% BaTiO3 reinforced PES composite film. The dielectric constant increased by ~ 227% compared with pure PES resin (4.1 at 1 kHz) and the dielectric loss maintained around 10−2 magnitude, which performed better dielectric properties. The tensile strength of 10 wt% BaTiO3/PES composite films (72 MPa) reached the highest value in comparison with those of pure PES (58 MPa) due to the strengthened interaction between particles and matrix. Further increase of BaTiO3 content, the tensile strength and elongation at break decreased slightly but remained an excellent flexibility from the PES matrix. The temperature at weight loss 5% (T5%) of composite film with 40 wt% of BaTiO3 content reached up to 503 °C in N2 atmosphere. All the BaTiO3/PES composite films performed the concentrated glass transition temperature (Tg) around 229 °C. In sum, excellent thermal stability and dielectric properties would make the BaTiO3/PES composite films become the fine potential candidates for dielectric composites in the capacitors.

Study on magnetic and dielectric properties of BaTiO3/MnCr0.2Fe1.8O4 composite material

BaTiO3 (BT)/MnCr0.2Fe1.8O4 (MCF) composites were prepared by solid state reaction via sol-gel process and sintered at 900 °C for 1 h. The weight percentages of BT/MCF composites were 0/100, 20/80, 40/60, 60/40, 80/20, 100/0. Phase composition and microstructure of the sintered BT/MCF composites were characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, respectively. Magnetic and dielectric properties of the sintered composites were also studied. The XRD results showed that all sintered composites exhibit the main phase of tetragonal perovskite structure of BT and cubic spinel structure of MCF, that the peak intensity of BT phase increases with increasing BT content. However, BaFe12O19 and α-Fe2O3 extra phases were also observed for all composites. The microstructure of the composites reveals polyhedral grains for MCF phase and BT phase with the grain size of about 0.61–1.93 μm and 0.51–1.12 μm, respectively. All sintered composites present hard ferromagnetic behavior whereas the pure BT and pure MCF are non-ferro/ferrimagnetic and soft magnetic, respectively. Saturation magnetization (Ms) of the sintered composites tends to decrease with increasing BT content, giving the Ms of 6–19 emu/g and Hc of 1.6–2.1 kOe. Dielectric properties of the composites showed that the εr and tanδ of all composites derive from ferroelectric BT behavior and hopping conductivity behavior in ferrite phase which is related to Maxwell-Wagner interface polarization model, leading to dielectric dispersion. The complex impedance spectroscopy indicates the heterogeneous structure consisting of semiconducting grain and insulating grain boundary.

Structural, optical, thermal, and dielectric properties of polyethylene oxide/carboxymethyl cellulose blend filled with barium titanate

Nanocomposite films of polyethylene oxide/carboxymethyl cellulose (PEO/CMC)/barium titanate (BaTiO3) were prepared using the solution casting technique. The results of X-ray diffraction (XRD) analysis depicted the semicrystalline nature of PEO/CMC, which was largely reduced due to BaTiO3 loading. Fourier transform infrared (FT-IR) spectroscopy showed the interaction between the components of blend, PEO and CMC, through the formation of hydrogen bond and confirmed the interaction between BaTiO3 and the functional groups of PEO/CMC, in particular C-O-C for PEO and COO− for CMC. From the Ultraviolet/visible (UV/vis.) absorption spectra, the sharp absorption edge in the UV range for the filled samples was red shifted and the optical energy gap was also calculated. The effect of BaTiO3 on the glass transition, melting point, and decomposition temperatures of the prepared samples was investigated using differential scanning calorimetry (DSC) technique. From the AC conductivity results, the electrical properties were improved depending on temperatures, frequencies, and the BaTiO3 content within the polymeric matrix. This indicated the presence of charge carriers that transported within defect sites by hopping. Furthermore, the mechanism for AC conduction and its dielectric parameters had been studied. Transmission electron micrographs revealed the cubic shape for BaTiO3 with an average size range of 15–50 nm. These observations indicate that these nanocomposite samples are potential candidates in various industrial applications, such as pyroelectric sensors and electromechanical transducers, and in ceramic capacitors as a dielectric material inserted between the two electrodes.

Dominant Role of Young's Modulus for Electric Power Generation in PVDF⁻BaTiO₃ Composite-Based Piezoelectric Nanogenerator.

The electric power output of a piezoelectric nanogenerator (PENG) depends on the various physical parameters of the constituent materials, including the piezoelectric coefficient, Young’s modulus, and dielectric constant. Herein, we report the mechanical and electrical properties of a poly(vinylidene fluoride)–BaTiO3 (PVDF–BTO) composite-based PENG. Variation of the BTO nanoparticle (NP) content enabled the systematic tuning of the physical parameters that are related to power generation in the composite. The Young’s modulus of the PVDF–BTO composite initially increased, and then eventually decreased, with the increasing BTO content, which was probably due to the clustering effect of the high modulus BTO NPs. The dielectric constant of the composite continuously increased as the BaTiO3 content increased. The piezoelectric outputs were greatly enhanced at 10 wt% of BTO, where the Young’s modulus was the highest. These results indicate that the Young’s modulus plays an important role in the piezoelectric power generation of the composite-based PENGs.

Role of sodium deficiency on the relaxor properties of Bi1/2Na1/2TiO3-BaTiO3

The influence of A-site deficiency on the relaxor properties in the lead-free (1-x)(Bi1/2Na1/2)TiO3-xBaTiO3 solid solution system was studied by intentionally reducing Na content in reference to the stoichiometric compositions. We observed that for all compositions, the higher the level of Na deficiency was, the lower the transition temperature from a ferroelectric to relaxor state became. The compositions with intermediate BaTiO3 contents (x = 0.06, 0.09, 0.13, and 0.40) showed sprout-shaped strains and pinched polarization curves at room temperature, indicating a crossover from a non-ergodic relaxor to ergodic relaxor state above a certain level of Na deficiency. We demonstrate that the presence of recently proposed oxygen octahedral tilt disorder as a prerequisite for the relaxor features in this system is not necessarily true, but the presence of stress-field-induced defect dipoles matters. A transmission electron microscopy confirmed that micro domains break down into nano domains with increasing Na deficiency level.

An Alternative Way To Enhance Piezoelectricity and Temperature Stability in Lead-Free Sodium Niobate Piezoceramics.

To further balance the relationship between piezoelectricity and temperature stability, the (0.975 - y)NaNbO3- yBaTiO3-0.025BaZrO3 ( y = 0-0.20) ceramics are developed by constructing a wide tetragonal phase region. Effects of BaTiO3 on the relationships among phase structure, electrical properties, and temperature dependence are investigated. With increasing BaTiO3 contents, the ceramics endure the structural evolutions from orthorhombic phase to tetragonal phase, and then to relaxor cubic phase. A wide tetragonal phase zone of 24-180 °C can be realized in the ceramics with y = 0.08, together with an enhanced piezoelectric coefficient d33 = 215 pC/N. Intriguingly, excellent temperature stability of unipolar strain ( Suni) and piezoelectric coefficient ( d33) are observed in the ceramics with y = 0.08 within 20-180 °C. This work provides an alternative way to enhance piezoelectricity and temperature stability in lead-free piezoceramics.

Influence of BaTiO3 on Magnetic and Transport Properties of La0.7Sr0.3MnO3-BaTiO3 Nanocomposite

La0.7Sr0.3MnO3 (LSMO)-BaTiO3 (BTO) nanocomposites have been synthesized by adding different amounts of BTO using the sol-gel method. The structural analysis confirms that both phases coexist in the composite samples with the rhombohedral and tetragonal structure for LSMO and BTO, respectively. The magnetization measurement shows a decrease in magnetization with the increase in BTO concentration and a signature of the spin glass-like characteristics of the nanocomposite. The dielectric behavior indicates the existence of the magneto-electric coupling between LSMO and BTO phase. The measurement of transport properties shows that resistivity increases with BTO concentration and metal-insulator (M-I) transition temperature shifts towards lower temperature. The low-temperature (T < 50 K) resistivity behavior of the samples is analyzed by using the Kondo-like transport model. The results show the spin-disordered scattering increases with the increase in the amount of BTO in LSMO phase. The low-field magnetoresistance (LFMR) of the nanocomposite is improved as compared to the pure LSMO. The highest value of LFMR achieved for LSMO-BTO composite at 10 K is 35.5% with a 1 T magnetic field.

Low-firing behavior, microstructure, and electromagnetic properties of a ferroelectric-ferromagnetic composite material with multiple doping

A series of BaTiO3-Ni0.62Cu0.25Zn0.16Fe1.98O4 ferroelectric-ferromagnetic composites with Li2CO3-V2O5-Bi2O3 multiple doping were prepared by the solid-state reaction at 900 °C–1000 °C, and the low fired (<961 °C) samples can adapt to the low temperature cofired ceramic (LTCC) technology. The relative density of all sintered composites was higher than 96%, and particularly for the low fired composites, it was in the range of 97.1%–99.5%. The variation of magnetic properties with BaTiO3 content was investigated combining with microstructure and two types of magnetization (demagnetization) processes. A novel method for calculating the microstructure parameter δ∗/D of the multiple doping composite systems has been deduced so that the magnetic circuit model can be used to predict the magnetic properties of the composites, and the experimental results matched well with the fitting curve. The dielectric behavior of the composites has been investigated in non-dispersive region (106∼108 Hz) and dielectric dispersion region (108∼1010Hz). Through combing grain size effect and phase transition, the influence of sintering temperature and BaTiO3 content on permittivity ε′ and dielectric dispersion of the composites have been discussed. In the non-dispersive region, the maximum ε′ of composites (256.07) was obtained in the sample with 90 wt% BaTiO3 (sintered at 950 °C). In the dispersion region, among all composites, both the maximum relaxation frequency 1.24 GHz and maximum resonance frequency 1.16 GHz were obtained in low fired samples.