Standard Double Sintering Ceramic Method Research Articles

Enhanced performance of magnetoelectric voltage coefficient in giant magnetostrictive (Ni0.7Mg0.3Fe2O4)/piezoelectric (BaZr0.2Ti0.8O3) composites

The non-toxic lead-free multiferroic composite samples Ni0.7Mg0.3Fe2O4/BaZr0.2Ti0.8O3 were synthesized by using standard double sintering ceramic method. The composite samples are found to exhibit dielectric response, which might be associated with Maxwell-Wagner type interfacial polarization and Koop's phenomenological theory. The variation of DC conductivity with respect to temperature revealed the conduction of electrons i.e. due to the small polarons hopping mechanism. The synthesized ME composite samples show a representative magnetic hysteresis (M − H) loop type behaviour at room temperature. In a previous report, the response of ME voltage coefficient 4.262 mVcm-1.Oe was determined for (30%) Ni0.8Mg0.2Fe2O4 + (70%) BaZr0.2Ti0.8O3 composites at 5.0 kOe applied DC magnetic field. But in this report, we improved the ME voltage coefficient for the composition 50% (Ni0.7Mg0.3Fe2O4) + 50% (BaZr0.2Ti0.8O3) which is a lead-free ME composite with the massive ME voltage coefficient of 8.562 mV/cm.Oe was achieved. Hence, the estimated results can provide experimental guidance for the optimal design of high-performance magnetoelectric devices and render better support for the technological development in the field of magnetoelectricity.

Synthesis of type-II based (1-x)Ba0.6(Ca1/2Sr1/2)0.4Ti0.5Fe0.5O3+(x)Ni0.40 Zn0.45Cu0.15Fe1.9Eu0.1O4 composites via standard solid state reaction method and investigation of multiferroic properties

A series of multiferroic composites, (1-x)Ba0.6(Ca1/2Sr1/2)0.4Ti0.5Fe0.5O3+(x)Ni0.4Zn0.45 Cu0.15Fe1.9Eu0.1O4 ((1-x)BCSTFO+(x)NZCFEO) where x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0 have been synthesized by standard double sintering ceramic method sintered for 3 hours at 1200°C in air. The X-ray diffraction patterns reveal that the multiferroics and the parent ceramic samples crystallize in simple cubic structure with a slightly distored lattice parameter. The X-ray and bulk density increase with the increasing ferrite content. Consequently, the porosity decreases indicating better crystallization. A decreasing trend in dielectric constant is observed while the relative quality factor (RQF) increases significantly with the increasing ferromagnetic NZCFEO. At the same time, M–H hysteresis loops reveal that ferromagnetic property enhances with the addition of Ni0.40Zn0.45Cu0.15Fe1.9Eu0.1O4 (NZCFEO). The highest values of coercive field ∼ 92 O and saturation magnetization ∼1.37 emu/g are observed for x = 10% and x = 50% compositions respectively. Additionally, the permeability enhances up-to x = 30% but decreases with further doping. The room temperature resistivity rises due to the decrease in hopping mechanism. The samples exhibit a decreasing trend for resistivity with the increase of temperature. The dopant concentration has also shown an impressive impact on the activation energy. As a result, the multiferroic properties of (1-x)BCSTFO+(x)NZCFEO have been significantly improved considering the measured magnetic and ferroelectric properties.

FT-IR Studies of Nickel Substituted Polycrystalline Zinc Spinel Ferrites for Structural and Vibrational Investigations

FT-IR spectra of Ni1-sZnsFe2O4 spinel ferrite, s changed by 0.2 according to 0.0 s 1.0, have been analyzed in the frequency range (350−1000) cm-1. Six polycrystalline ferrites samples were synthesized using the conventional standard double sintering ceramic method. Two main absorption bands were observed, their positions were found to be strongly dependent on s-value. The high frequency band in the range 550-600 cm−1 and a low frequency band at around 400 cm−1 were assigned to tetrahedral Td and octahedral Oh sites, respectively, of spinel lattice. Force constant (FC) was calculated for Tdand Oh sites and was found to decrease with increasing Zn ions. Threshold frequency nth for the electronic transition was determined and found to increase with increasing Zn ions. Cations distribution for the prepared mixed ferrite was concluded based on the FT-IR spectra. The ionic radii for each site were correlated to the cations distribution of the given ferrite.

Structural, magnetic and magnetoelectric properties of the magnetoelectric composite material

(x) CoFe2O4 + (1 − x) Ba0.9Sr0.1TiO3 magnetoelectric (ME) composites with x = 0.1, 0.2, 0.3, 0.4 and 0.5 were prepared by a conventional standard double sintering ceramic method. The magnetic and ME properties of composites consisting of cobalt ferrite (CoFe2O4) and barium strontium titanate (Ba0.9Sr0.1TiO3) were investigated. The X-ray diffraction analysis was carried out to confirm the phases formed during sintering and also to calculate the lattice parameters. The hysteresis measurements were done to determine saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (Hc) of the samples. The ME voltage coefficient (dE/dH)H was studied as a function of intensity of the magnetic field. The measured ME response demonstrated strong dependence on the volume fraction of CoFe2O4 and the applied magnetic field. A large ME voltage coefficient of about 1,380 µV/cm/Oe was observed for 10 % CoFe2O4 + 90 % Ba0.9Sr0.1TiO3 composite.

Electric and Dielectric behavior of Ni-Co-Cd Ferrite

Cadmium doped nickel-cobalt ferrite with chemical formula Ni0.8-xCo0.2CdxFe2O4 (x=0.1, 0.2 and 0.3) is prepared by standard double sintering ceramic method. Electric and dielectric properties of nickel cobalt cadmium ferrite are investigated. Formation of single phase is confirmed by X-ray Diffraction pattern. The average grain size of the samples is determined by scanning electron micrographs. The D.C resistivity (ρ) is determined as a function of temperature in the range 300K-1073K by two probe method. Dielectric constant (έ) is determined by measuring capacitance (Cp). Variations of Dielectric constant (έ) with frequency as well as temperature are studied. A.C. conductivity (σac) is derived from dielectric constant (έ) and loss tangent (tan δ) values

Preparation, Characterization and D.C. Resistivity of y(Ni0.7Co0.2Cd0.1Fe2O4)+ (1-y) Ba0.9Sr0.1TiO3 Magnetoelectric Composites

The magnetoelectric composites having chemical formula y(Ni0.7Co0.2Cd0.1Fe2O4)+(1-y) Ba0.9Sr0.1TiO3 were prepared by standard double sintering ceramic method . Presence of constituent phases in the ME composite is confirmed by X-Ray Diffraction pattern. Purity of composition in ME composite was studied by EDAX spectrum. The Microstructural of the samples was studied by scanning electron micrographs. The effects of ferrite content on average grain size and DC resistivity were also studied which is important regarding the improvement of properties of the product materials.

Preparation and characterization of Co2+ substituted Li–Dy ferrite ceramics

Abstract Stoichiometric compositions of ferrites with the chemical formula Li 0.5−0.5 x Co x Fe 2.4−0.5 x Dy 0.1 O 4 with x =0, 0.25, 0.5, 0.75, 1.0 were prepared by the standard double sintering ceramic method. X-ray diffraction analysis confirmed the cubic spinel structure of the prepared samples. The structural, morphological and magnetic properties were studied by X-ray diffraction, infra-red spectroscopy (IR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and ac susceptibility measurements. Lattice constant, grain size and density increase whereas porosity decreases with the increase in Co 2+ substitution. IR measurements show the characteristic ferrite bands. Spectral absorption bands were observed in IR spectroscopic analysis at ν 1 =564−601 cm −1 , ν 2 =486−519 cm −1 and ν 3 =551−578 cm −1 . The cation distribution estimated by the X-ray diffraction is supported by magnetization and susceptibility studies. The saturation magnetization decreases from 44.25 to 17.14 emu/g whereas coercivity remarkably increases from 240.69 to 812.14 emu/g with increasing Co 2+ substitution. The mechanisms involved are discussed.

Dielectric Property of 0.45NiFe2O4+0.55BaTiO3 Ceramic Composites

The standard double sintering ceramic method was used to prepare the 0.45NiFe2O4 +0.55BaTiO3 composites. Complex impedance analysis enables us to separate the contributions from grain and grain boundary in the samples. Impedance spectroscopy measurements were conducted in a frequency range from 20 Hz to 2 MHz and in a temperature range from 75 to 200°C. The impedance measurements have also shown the evidence of grain boundary conduction and lowering of barrier to the motion of charge carriers with rise in temperature. We also found that the relaxation frequency shift to high side with increase in temperature.

Infrared and structural studies of Mg 1– xZn xFe 2O 4 ferrites

Compositions of polycrystalline Mg–Zn mixed ferrites with the general formula Mg 1− x Zn x Fe 2O 4 (0≤ x≤1) were prepared by the standard double sintering ceramic method. The structural properties of these ferrites have been investigated using X-ray diffraction and infrared absorption spectroscopy. The lattice parameter, particle size, bonds length, force constants, density, porosity, shrinkage and cation distribution of these samples have been estimated and compared with those predicted theoretically. Most of these values were found to increase with increasing Zn content. The energy dispersive (EDS) analysis confirmed the proposed sample composition. The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs showed aggregates of stacked crystallites of about 200–800 nm in diameter. Far infrared absorption spectra showed two significant absorption bands. The wave number of the first band, ν 1, decreases with increasing Zn content, while the band, ν 2 shifts linearly towards higher wave numbers with Zn contents, over the whole composition range. The room temperature electrical resistivity was found to decrease as Zn-content increases. Values of the vacancy model parameters showed that the packing factors P a and P b decrease, the fulfillment coefficient, α, remains almost constant and the vacancy parameter, β, strongly increases with increasing Zn content in the sample. The small values of P a , P b , α and the strong increase of the vacancy parameter, β, indicate the presence of cation or anion vacancies and the partial participation of the Zn 2+ vacancies in the improvement of the electrical conductivity in the Mg–Zn ferrites.

Microstructure and magnetic studies of Mg–Ni–Zn–Cu ferrites

Soft Mg–Ni–Zn–Cu spinel ferrites having general chemical formula Ni x Mg 0.5− x Cu 0.1Zn 0.4Fe 2O 4 (where x = 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared by standard double sintering ceramic method. The samples were characterized by X-ray diffraction at room temperature. The X-ray diffraction (XRD) study revealed that lattice parameter decreases with increase in Ni content, resulting in a reduction in lattice strain. The electrical and magnetic properties of the synthesized ferrites have been investigated as a function of temperature. The variation of initial permeability and AC susceptibility with temperature exhibits normal ferrimagnetic behavior. The variation of initial permeability with frequency is studied. The Curie temperature ( T C) in the present work was determined from initial permeability and AC susceptibility. The Curie temperature increases with Ni content.

Synthesis, Structural and Physical Properties of Cu<sub>1–x</sub>Zn<sub>x</sub>Fe<sub>2</sub>O<sub>4</sub> Ferrites

Zn substituted Cu-Zn ferrites with a composition Cu1-xZnxFe2O4 have been synthesized by standard double sintering ceramic method and characterized by X-ray diffraction. The single-phase cubic spinel structure of all the samples has been confirmed from X-ray diffraction analyses. The lattice constant is found to increase linearly with the manganese content obeying Vegard’s law. This increase in lattice parameter is explained in terms of the sizes of component ions. It is well known that density plays a key role in controlling the properties of polycrystalline ferrites. The X-ray and bulk densities of the Cu-Zn ferrite is significantly decreased whereas porosity increased with increasing Zn concentration, thereby giving an impression that zinc might be helping in the densification of the materials. SEM micrographs exhibit a decrease in grain size with increasing Zn content. The real part of initial permeability, μ′ increase with increasing Zn contents upto x = 0.5 after that it decreases with higher Zn content.

Far-infrared spectra for copper–zinc mixed ferrites

Infrared spectra of Zn 2+ ions substituted Cu ferrites with the general formula Cu 1−xZn xFe 2O 4 (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1) have been analyzed in the frequency range 200–1000 cm −1. These mixed ferrites were prepared by the standard double sintering ceramic method. Two prominent bands were observed, high-frequency band ν 1 around 550 cm −1 and low-frequency band ν 2 around 395 cm −1 and assigned to tetrahedral and octahedral sites for spinel lattice, respectively. On introducing zinc ions IR spectra indicate new shoulders or splitting on tetrahedral absorption bands around 600 and 700 cm −1. A small absorption band ν 3 was observed around 310 cm −1. This indicates the migration of some Zn 2+ ions to octahedral site. Another small weak absorption band was also observed around 265 cm −1; its intensity increased with Zn content. Force constant was calculated for both tetrahedral and octahedral sites. Threshold frequency ν th for the electronic transition was determined and found to increase with an increase in Zn ions. The half bandwidth for each site was calculated and the ratio seemed to increase with an increase in zinc content. The cation distribution for these ferrites was estimated in the light of IR spectra.

Structure and magnetic properties of the ZnxMg1-xFe2O4 ferrites

Spinel magnesium-zinc ferrites ZnxMg1-xFe2O4 (0≤x≤1) prepared by the standard double sintering ceramic method have been investigated using X-ray (XRD) diffraction technique and Mössbauer spectroscopy measurements at 295K and 78K. The crystal structure is found to be single cubic spinel whose lattice parameter 'a' increases with increasing Zn content. The Mössbauer spectra of the samples taken at 78 K are found to be magnetically ordered for x≤0.5, paramagnetic for x≥0.8 and show very broad patterns for intermediate concentration of Zn2+. The variation of the magnetic properties with the Zn concentration has been explained on the basis of the cation distribution driven from the Mössbauer measurements.

Effect of copper substitution on electrical and magnetic properties of NiFe 2O 4 ferrite

The effect of copper ion substitution for nickel on electrical and magnetic properties of NiFe 2O 4 ferrite is reported. The spinel ferrite system Ni 1− x Cu x Fe 2O 4 with x = 0, 0.1 and 0.2 was synthesised by standard double sintering ceramic method. X-ray diffraction study confirms the formation of single-phase nickel copper ferrites with space group of Fd3 m. The investigation on dielectric constant, dielectric loss tangent and ac conductivity was carried out in the frequency range 100 Hz–1 MHz at room temperature. Dielectric constant and loss tangent were found to decrease as the frequency increases. This is attributed to the Maxwell–Wagner polarization. Temperature-dependent dc resistivity was carried out in the temperature range from 300 to 800 K. Conduction mechanism in these ferrites is discussed on the basis of electron exchange between Fe 2+ and Fe 3+ ions on the octahedral B-sites. The hysteresis measurements were done to determine saturation magnetization ( M s) and coercivity ( H c) of the samples. The Cu content has a significant influence on the electromagnetic properties, such as saturation magnetization, coercivity, dielectric constant, loss tangent, dc resistivity and ac conductivity. The possible reasons that are responsible for the composition dependence of the properties were discussed.

Studies on structural and electrical properties of Co 1− xNi xFe 1.9Mn 0.1O 4 ferrite

Nickel-doped iron-deficient cobalt ferrite with small amount of manganese having the chemical composition Co 1− x Ni x Fe 1.9Mn 0.1O 4, with x = 0.2, 0.4, 0.6 and 0.8, were prepared by standard double sintering ceramic method. The spinel phase formation was confirmed by X-ray diffraction (XRD). The DC resistivity measurements with temperature indicate a semiconducting behavior showing a linear decrease with increasing temperature and the doping of Ni enhances the resistivity. Maximum resistivity of the order of 10 9 Ω cm was found for composition x = 0.8. Room temperature dielectric constant measurements with frequency (100 Hz to 1 MHz), show usual dielectric dispersion. Also, the variation of room temperature AC conductivity as a function of frequency were studied and explained by using Maxwell–Wagner two-layer model. The studies on dielectric constant ( ɛ′), loss tangent (tan δ) and AC conductivity ( σ AC), at four different frequencies (viz., 1, 10, 100 kHz and 1 MHz), with temperature were made.

Magnetic properties and magneto electric effect in ferroelectric rich Ni 0.5Zn 0.5Fe 2O 4+BPZT ME composites

Magneto electric composites with composition ( x) Ni 0.5Zn 0.5Fe 2O 4+(1– x) Ba 0.8Pb 0.2Zr 0.8Ti 0.2O 3 (BPZT—barium lead zirconate titanate) in which x varies as 0.0, 0.15, 0.30, 0.45 and 1.0 mol% were prepared by standard double sintering ceramic method. The presence of constituent phases such as ferrite and ferroelectric was confirmed by X-ray diffraction. The structural analyses were carried out by using X-ray diffraction pattern. Scanning electron micrographs (SEM) were taken to understand the microstructure of the samples. The calculated values of the porosity of the samples lie between 4.5% and 16.2%. The hysteresis measurements were made to determine saturation magnetization ( M s), magnetic moment ( μ B) and coercivity ( H c). From the AC susceptibility measurements the contribution of both the single domain (SD) particles of the ferrite phase and mixed domain (SD+MD) particles of the composites in ME output were explained. The static magneto electric voltage coefficients (d E/d H) H were measured as a function of intensity of magnetic field and the maximum ME coefficient were observed for the composites with 30% of ferrite+70% of ferroelectric phase.

Studies on magnetic and magnetoelectric properties of the NiFe2O4–Ba0.7Sr0.3TiO3 composites

The magnetic and magnetoelectric properties of magnetoelectric (ME) composites consisting of with nickel ferrite (NiFe2O4) and barium strontium titanate (Ba0.7Sr0.3TiO3) were investigated. The composites were prepared by standard double sintering ceramic method. The X-ray diffraction analysis was carried out to confirm the phases formed during sintering and also to calculate the lattice parameters. The hysteresis measurements were done to determine saturation magnetization (Ms), remenance magnetization (Mr) and coercivity (Hc) of the samples. The magnetoelectric voltage coefficient (dE/dH)H was studied as a function of intensity of the magnetic field. The measured magnetoelectric (ME) response demonstrated strong dependence on the volume fraction of NiFe2O4 and the applied magnetic field. A large ME voltage coefficient of about 560 μVcm−1Oe−1 was observed for 15% NiFe2O4 + 85% Ba0.7Sr0.3TiO3 composite.

Effect of resistivity on magnetoelectric effect in (x)NiFe2O4–(1−x)Ba0.9Sr0.1TiO3 ME composites

Abstract The standard double sintering ceramic method was used to prepare the magnetoelectric composites having ferrite and ferroelectric phase. The coexistence of ferrite (NiFe2O4) and ferroelectric (Ba0.9Sr0.1TiO3) was confirmed by the XRD patterns and the lattice constant for each composition is calculated. SEM micrographs were taken to understand the microstructure of the samples. The dielectric constant was studied as a function of frequency in the range 100 Hz to 1 MHz. The AC conductivity as a function of frequency and DC resistivity as a function of temperature were studied for different compositions. The static value of the magnetoelectric conversion factor, i.e. (dE/dH)H was studied as a function of applied magnetic field. Lastly the dependence of Magnetoelectric effect (ME) effect on DC resistivity is shown in this paper.

Dielectric and magnetic properties of xNiFe 2O 4+(1− x)Ba 0.9Sr 0.1TiO 3 composites

Magnetoelectric composites, namely, xNiFe 2O 4+(1− x)Ba 0.9Sr 0.1TiO 3 were prepared by standard double sintering ceramic method. The X-ray diffraction analysis was carried out to check the phases formed during sintering and to calculate the lattice parameters. Scanning electron microscope (SEM) micrographs were taken to understand the microstructure of the samples. The dielectric constant ( ε′) and loss tangent (tan δ) were measured as a function of frequency in the frequency range 100 Hz–1 MHz. Variation of dielectric constant and loss tangent with temperature and composition has been reported. The hysteresis measurements were done to determine saturation magnetization ( M S) and coersivity ( H c). The variation of saturation magnetization and magnetic moment is interpreted in terms of composition.

Structural, electrical and magnetic properties of xNiFe 2O 4 + (1 − x)Ba 0.8Sr 0.2TiO 3 ME composites

Magnetoelectric composites, namely xNiFe 2O 4 + (1 − x)Ba 0.8Sr 0.2TiO 3 were prepared by standard double sintering ceramic method. The X-ray diffraction measurements were carried out to check the phase purity and to calculate the lattice constants. scanning electron microscopy (SEM) micrographs were taken to understand the microstructure of the samples. Dielectric property such as dielectric constant ( ε ′ ) was also studied as a function of frequency in the range 100 Hz–1 MHz. The ac conductivity as a function of frequency and dc resistivity as a function of temperature were studied for different compositions. The hysteresis measurements were done to determine saturation magnetization ( M s) and coersivity ( H c) and magnetic moment was calculated. Effect of resistivity on ME voltage coefficient is studied.