M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

Ava i l ab l e on l i ne a t www.sc i enced i r ec t . com

ScienceDirectwww.e l sev i e r . com/ loca te /matcha r

Magnetic and electric properties of the lead free

ceramic composite based on the BFN andferrite powders

Dariusz Bocheneka,1, Przemysław Niemieca,1, Artur Chrobakb,Grzegorz Ziółkowskib, Artur Błachowskic

aUniversity of Silesia, Department of Materials Science, 2, Śnieżna St., Sosnowiec 41-200, PolandbUniversity of Silesia, Institute of Physics, 4, Uniwersytecka St., Katowice 40-007, PolandcPedagogical University, Institute of Physics, 2, Podchorążych St., Cracow 30-084, Poland

A R T I C L E D A T A

E-mail address: dariusz.bochenek@us.edu1 Tel.: +45 32 3689584; fax: +45 32 3689 563.

1044-5803/$ – see front matter © 2013 Elseviehttp://dx.doi.org/10.1016/j.matchar.2013.10.02

A B S T R A C T

Article history:Received 18 July 2013Received in revised form 24 July 2013Accepted 30 October 2013

Ferroelectromagnetic BaFe0.5Nb0.5O3 (BFN) ceramics and ferroelectromagnetic compositesbased on BFN powder and ferrite powder have been obtained in the presented work. Thepercentage of components in a two-phase compositewas: biferroic powder BFN in the amountof 90%, and nickel–zinc ferrite Ni1 − xZnxFe2O4 for x = 0.36 in the amount of 10%. The synthesisof the components of the BFN–ferrite compositewas performed using the calcinationmethod.Final densification of the synthesized powder was done using free sintering.For the obtained two-phase ceramic BFN–ferrite composite, the XRD, microstructure, EDS,dielectric, impedances, magnetic, Mössbauer and electrical hysteresis loop investigationswere performed. The obtained results show correlations between the magnetic subsystemand the electrical subsystem of the ferroelectromagnetic composite. Such properties of theobtained composite give a possibility to use them in memory applications of a new type.

© 2013 Elsevier Inc. All rights reserved.

Keywords:FerroelectromagneticsFerroelectromagnetic compositesMultiferroic compositesLead-free ceramics

1. Introduction

Ferroelectromagnetics are materials exhibiting magnetic prop-erties (ferromagnetic, ferrimagnetic and anti-ferromagnetic)and electric properties (ferroelectric, ferrielectric and anti-ferroelectric), and belong to the group of multiferroics of mis-cellaneous applications [1,2]. Pb(Fe0.5Nb0.5)O3, Pb(Fe2/3W1/3)O3,Pb(Fe0.5Ta0.5)O3 as well as multicomponent materials obtainedon their basis, can be included to multiferroics [3–8]. Since leadis the principal component of these materials, currently, foran increasing number of applications, lead-free materials ofoptimal parameters are being sought, capable of replacingthe lead materials. BaTiO3, SrTiO3 and BiFeO3 altogether with

.pl (D. Bochenek).

r Inc. All rights reserved.7

Bi0.5Na0.5TiO3, K0.5Na0.5NbO3, Na0.5Bi0.5TiO3, BaFe0.5Nb0.5O3,Bi5Ti3FeO15, SrBi2Nb2O9 as well as composites and multicom-ponent compounds obtained on their basis, can be included tothe group of lead-free materials [9–13].

Multiferroic composites may be divided into two-phase(with ferroelectric and magnetic properties — ceramic com-posites) and multiphase types, where aside from ferroelectricand magnetic phases, an additional, for instance, polymerphase (called ceramic–polymer composite) appears, howeverthe composite acquires new properties.

In the research, a composite of ferroelectric and magneticproperties on the basis of ferroelectromagnetic BaFe0.5Nb0.5O3

BFNpowder and ferromagnetic nickel–zinc ferrite, was obtained.

37M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

Its elementary ferroelectric and magnetic properties wereanalyzed, including a correlation between the magnetic andelectric subsystems of this material.

The barium iron niobate: BaFe0.5Nb0.5O3 (BFN) is a ferroelec-tric material with a diffuse phase transition and high value ofelectric permittivity, and is also an anti-ferromagnetic insulatorat TN = −248 °C (25 K) with weak ferromagnetic behavior at−268 °C (5 K) [14–16]. This material is useful for high voltagecapacitors and other applications [17]. The nickel–zinc ferrite(Ni0.64Zn0.36Fe2O4) belongs to the so-called soft ferrites of highmagnetic permeability and resistance values. The soft ferritesare applied in, inter alia, electric machines for transformation ofelectric energy (transformers), generation of electric energy(generators and alternators), transformation of electric energyinto mechanical energy (electric motors), magnetic shielding,telecommunications filters, distance sensors, delay lines, EMIfilters, etc.

2. Material and Methods

In order to obtain lead-free two-phase ceramic composite,ceramic powder of BaFe0.5Nb0.5O3 (BFN) chemical compositionand of ferroelectromagnetic properties, as well as nickel–zincNi0.64Zn0.36Fe2O4 ferrite powder of ferromagnetic properties, wasused. Fig. 1 shows images of the ferrite powder and microstruc-ture of the fracture of a ceramic ferrite sample was carried out inthe following conditions: Ts = 1150 °C and Ts = 2 h. In case ofsintering of compacts of the ferrite powder, a characteristicgrowth of the grains (of the shape similar to hexahedron) can beobserved.

The BaFe0.5Nb0.5O3 (BFN) powder was obtained bymeans of asynthesis of oxides (Fe2O3, Nb2O5) and bariumcarbonate (BaCO3),according to the following reaction: BaO + 0.25Fe2O3 + 0.25Nb2-O5 → BaFe0.5Nb0.5O3. Themixture of constituent powders of BFNwas synthesized by calcination of the powders in 1250 °C for 4 h.The other component of the composite of strong ferromagneticproperties (Ni0.64Zn0.36Fe2O4 ferrite powder) was synthesized bycalcination in 1100 °C for 4 h.

The composition of the composite was: 90% of BFN powderand 10% of ferrite powder. The constituent powders used forobtaining the composite were mixed in a FRITSCH Pulverisette 6planetary ball mill for 15 h (wet mixing) in ethyl alcohol.

Fig. 1 – SEM images powder Ni0.64Zn0.36Fe2O4 and

The synthesis of the constituent powder's mixture of thecomposite carried out in the following conditions: Tsynth =1250 °C and Tsynth = 4 h. For the purpose of the comparison,densification (sintering) of ceramics and the composite powderwas carried out by free sintering (FS) method in the sameconditions (Ts = 1350 °C and Ts = 2 h). In case of the compositesample additional sintering was carried out in reduced temper-ature (Ts = 1300 °C and Ts = 2 h). Electrodes were applied on thecomposite specimen surfaces by silver paste burningmethod forelectrical tests.

X-ray tests of the crystallographic structure were per-formed on a Philips X'Pert diffractometer. Microstructure testswere carried out using a HITACHI S-4700 scanningmicroscopewith EDS Noran Vantage system. Dielectric measurementswere performed on a capacity bridge of a QuadTech 1920Precision LCR Meter for a cycle of heating (at frequencies ofthe measurement field from υ = 0.02 kHz to 20 kHz), andmagnetic properties measurements using a SQUID magne-tometer (MPMS XL-7 Quantum Design) in the range oftemperatures from −271 °C to 27 °C and magnetic field to 7 Tand a magnetic Faraday scale in the range of temperaturesfrom 27 °C to 827 °C.

Transmission Mössbauer spectra were obtained by meansof a RENON MsAa-3 spectrometer with the velocity scalecalibrated by the Michelson–Morley interferometer. Spectrawere collected for the 14.41 keV resonant transition in 57 Feapplying commercial 57 Co(Rh) source kept together with theabsorbers at room temperature. Mössbauer absorbers wereprepared in the powder form. Data were processed withintransmission integral approximation as implemented in theMOSGRAF suite. All shifts of the spectra are reported versusroom temperature α-Fe.

3. Results and Discussion

The X-ray investigations are shown in Fig. 2. The pattern showsthat at room temperature, the BFN ceramics is single phasemonoclinic of perovskite structure (with the best fit to themodel00-057-0771 [18]) without the evidence of any additional phase.TheX-ray diffractionpatterns for the ferrite powderNiZnFe showa typical single phase cubic spinel. The X-ray analysis of the BFN–ferrite samples and the BFN ceramics exhibited the presence of

crack of the ceramic Ni0.64Zn0.36Fe2O4 sample.

Fig. 2 – Powders X-ray spectra: BFN, ferrite and BFN–ferrite composite.

38 M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

strong maxima originating from the BaFe0.5Nb0.5O3 (BFN) mate-rial, as well as weak reflections from the Ni0.64Zn0.36Fe2O4 ferritecomponent (Fig. 2), without the evidence of any additional phase.

The chemical compositions of the BFN–ferrite samples andthe BFN ceramics were analyzed by means of X-ray spectros-copy with EDS energy dispersion. The EDS examinationallowed to conduct qualitative and quantitative analyses ofdistribution of elements, consisting in an automatic scanningof the selected surface micro-areas (local analysis), as well as

Fig. 3 – EDS elements distribution for BFN cer

identifying the selected elements in an X-ray characteristicspectrum (the qualitative EDS analysis). The EDS analysisBFN–ferrite composite sample (Fig. 3) confirmed the assumedpercentage of the individual components, and the presence ofconstituent elements originating from the two components(the ferrite powder and ferroelectric BFN-type powder).

Fig. 4 presents microstructural SEM images of the BFNceramics samples and the BFN–ferrite composite fracturessintered at 1350 °C. The BFN ceramic microstructure is

amics, ferrite and BFN–ferrite composite.

Fig. 4 – SEM microstructure: a) BFN ceramic and b) composite BFN–ferrite, sintered at a temperature of 1350 °C.

39M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

characterized by a compact structure with densely packedgrains (Fig. 4a) with sparse (intergranular) closed pores. Amixed character of the fractures, i.e. on the edges and acrossthe grains, is present in this material, whereas in the BFN–ferrite composite, larger BFN powder grains (of a biggernumber of walls) surround smaller grains of magnetic ferrite(of tetrahedron sections) — Fig. 4b.

Reduction of sintering temperature by 50 °C in the BFN–ferrite composite reduces the excessive growth of the grains(Fig. 5), and the fracture (with prevalence) occurs after theedges of grains. The microstructure of this two-phasecomposite is characterized by smaller grains, in comparisonwith a composite obtained in a higher temperature (1350 °C).Bigger and properly crystallized BFN grains (of inhomogenoussize), as well as tiny ferrite grains (of tetrahedron sections), inthe microstructural image, are visible.

The temperature diagrams of electric permittivity (Fig. 6)illustrate a diffuse character of the phase ferroelectric–paraelectric transition in the BFN and BFN–ferrite composite[14]. The high values of electric permittivity in a very widetemperature interval are due to a disorder in the distributionof B-side ions in the perovskite unit cell. This may lead to theappearance of composition fluctuations and, as a conse-quence, to different local Curie temperatures in different

Fig. 5 – SEM microstructure BFN–ferrite composite, sinteredat low temperature (1300 °C).

regions of the ceramics. It creates a diffuse of phase transitionin BFN.

High values of electric permittivity in BFN might be alsorelated to a formation of layers (metal–semiconductor junc-tion) at a near-electrode surface, which equal to the sum ofcapacity of the sample's material and capacity of the creatednear-electrode surfaces [19]. The near-electrode surfaces canform in a majority of materials with a perovskite-typestructure, increasing at the same time values of electricpermittivity.

The analysis of dielectric properties of the two-phase BFN–ferrite composite revealed a significant increase of the maximalvalue of electric permittivity. Besides, the BFN–ferrite compositeexhibits an increase of diffuse of phase transition and frequencydispersion (a shift of phase transition temperature with anincrease of the frequency of measurement field — towardshigher temperatures). These changes of temperature progres-sions ε(T) of the BFN–ferrite composite might evidence theinfluence ofmagnetic subsystems on dielectric properties. Otherfactor influencing the character of transitions is also the increaseof electrical conductance in higher temperatures. The reductionof temperature of the BFN–ferrite composite sintering (1300 °C),decreases the values of electric permittivity (Fig. 6c).

The BFN ceramics and the BFN–ferrite composite dielectriclosses are substantial, and their temperature graphs tanδ(T) aresimilar (Fig. 7). In lower temperatures (up to about 150 °C), withan increase of the frequency of measurement field, an increaseof dielectric loss values occurs. The quantity of dielectric loss forBFN is close to the results presented by the authors [20]. Yet, incase of the BFN–ferrite composite, dielectric loss is lower (Fig. 7b).The reduction of temperature of the BFN–ferrite compositesintering (1300 °C) insignificantly reduces the values of dielectricloss (Fig. 7c).

Fig. 8 shows dependences of impedance of BFN ceramicsample and BFN–ferrite composite sample sintered at tem-perature 1300 °C and 1350 °C, for measurement frequencies:100 kHz and 1 MHz. The characteristic behavior of curves Z(T)for ferroelectric materials was observed. With increasedtemperature, value impedance systematically increases, andsubsequently after broad of maximum, it decreases violently.The BFN ceramics show the maximum of value of impedanceat higher temperature, in comparison with composite BFN–

Fig. 6 – Temperature dependencies of electric permittivity εfor a) BFN ceramics, b) composite BFN–ferrite sintered at atemperature of 1350 °C, and c) BFN–ferrite compositesintered at a temperature of 1300 °C (heating).

Fig. 7 – Temperature dependencies of the tangent ofdielectric losses tanδ for a) BFN ceramics, b) BFN–ferritecomposite sintered at a temperature of 1350 °C, andc) BFN–ferrite composite sintered at a temperature of 1300 °C(heating).

40 M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

ferrite samples. The higher temperature of sintering, the BFN–ferrite composite (1350 °C) shifts the maximum value ofimpedance towards lower temperature. With the increased

frequency of measuring field reduction of value impedance isobserved. It is associated with the occurrence of the frequencydispersion effect characteristic for ferroelectric materials.

Fig. 8 – Temperature dependences of impedance of BFNceramics and BFN–ferrite composite sintered at 1350 °C and1300 °C for frequencies: a) 100 kHz and b) 1 MHz.

Fig. 9 – Temperature and frequency dependent real Z′impedance spectra of BFN ceramic (a) and of BFN–ferritecomposite sintered at a temperature of 1350 °C (b). Inset: thepart of graph of Z′(f) at high frequency range.

41M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

The variation of the real Z′ part of impedance as a functionof frequency at different temperatures is shown in Fig. 9,varying from 150 to 350 °C for the BFN ceramic (Fig. 9a) and forthe BFN–ferrite composite (Fig. 9b). Inset: these figures showspart of graph of Z′(T) at high frequency range. The real Z′ partsof impedance decrease with an increase in frequency andtemperature.

Fig. 10 shows the variation of the imaginary Z″ parts ofimpedance as a function of frequency at temperatures from150 to 350 °C for the BFN ceramics (Fig. 9a) and for the BFN–ferrite composite (Fig. 10b). Inset: this figure shows magnifi-cation of Z″ at high frequency range. For both compositions,values of Z″ decrease with increasing frequency and temper-ature. For the BFN ceramics (inset of Fig. 10a) at 235 °C, adistinct peak appeared in Z″, at frequency slightly before103 Hz, while in case of the BFN–ferrite composite (inset ofFig. 10b) peaks appear before 103 Hz, however of weakerintensity and at a lower temperature (200 °C). Decreasingvalues of imaginary Z″ with increasing temperature indicatethe increasing loss in the samples (increase of conductivity). Itis shown that this Z″ peak became weaker in intensity, andshifts towards the high frequency side with increasing

temperature. This behavior indicates that the relaxation inthese materials is a thermally activated process. Connectionof all the curves at high frequency indicates the depletion ofspace charges at those frequencies [21].

The occurrence of relaxation peaks in the imaginary part ofthe complex impedance in this frequency range (inset ofFig. 9a) might be due to the existence of the space-charge layerin the BFN–ferrite composite sample. Space-charge polariza-tion mechanism prevails in heterogeneous structures, wherea material is assumed to be composed of different areas (grainand grain boundaries). These areas (phases) have differentelectrical conductivities and thus the accumulation of chargeswill be occurred at the phase boundary [22]. These pointcharges result in an additional space charge polarization (i.e.Maxwell–Wagner relaxation type), and it can by assumed thatthe maximum is originating from the Maxwell–Wagnerpolarization between the BFN phase with higher resistivityand the ferrite phase with much lower resistivity [22].

The relaxation time τ of the composite BFN–ferrite sampledecreases with an increasing temperature according to theequation ϖτ = 2πfmaxτ = 1 (Fig. 11). At higher temperatures,more electrons are thermally excited, and therefore the

Fig. 10 – Temperature and frequency dependent imaginaryZ″ spectra of BFN ceramic (a) and BFN–ferrite compositesintered at a temperature of 1350 °C (b). Inset: the part ofgraph of Z″(f) at high frequency range.

42 M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

relaxation time of the carrier becomes shorter and/or thedissipated thermal energy assists formed dipoles to followthe motion of the alternating field [23]. This analysis confirmsthe presence of temperature dependent electrical relaxation

Fig. 11 – Temperature dependence of the relaxation time (τ)for BFN–ferrite composite (Ts = 1350 °C). Inset: lnτ v. 1000/T.

phenomena in the BFN–ferrite composite. This variation of τcan be described by the known Arrhenius equation [1].

τ ¼ τ0 expΔEτkBT

� �ð1Þ

where:

τ0 characteristic relaxation time at infinite temperature,ΔEτ activation energy of the relaxation process,kB Boltzmann constant.

The plot of lnτ v.1000/T for the composite BFN–ferrite isshown in the inset of Fig. 11. The values of ΔEτ and τ0 werecalculated from the slope of the linear fit and are summarizedin Table 1.

The temperature relationship of magnetization M(T), in theexternal 0.1 T magnetic field, of the BFN–ferrite composite ispresented in Fig. 12a. TheM(T) curves comprise two components.The first one is ferro/ferrimagnetic with Curie temperature ofnearly 450 °C, while the second one is para/superparamagnetic,clearly visible at a temperature under −173 °C. Above thetemperature 460 °C, the BFN–ferrite composite is a paramagnetic.

The magnetic hysteresis loops M(H) of the ceramic BFN–ferrite composite obtained in the temperatures of −271 °C,173 °C and 27 °C are characteristic for soft ferromagneticmaterials (Fig. 12b). Thesematerials ought tohavehighmagneticpermeability (which allows achieving high values of magneticinduction with the use of weakmagnetizing current), the lowestpossible losses— the field embraced by a hysteresis loop (whichallows a high–performance energy conversion), high saturationinduction (allowing to achieve the highest mechanical power —proportional to the induction squared) and high resistivity (inorder to reduce power loss caused by eddy currents). Theceramic BFN–ferrite composite has properties and parametercharacteristics for a soft ferromagnetic material.

In the range of weakmagnetic fields and these, for which themagnetization curve changing its shape (curves), an increase ofthe sample's magnetization is caused by a growth of domains ofa privileged direction of magnetization, at the cost of adjacentdomains. It is related to the mechanism of domain's boundaryshifting (boundaries between the areas of spontaneousmagnetization), which is a reversible process up to the pointwhere the magnetic energy of the wall is comparable with theenergy of magnetic interaction. In stronger magnetic fields,

Table 1 – Parameters for BFN ceramics and BFN–ferritecomposite (Ts = 1350 °C).

BFN ceramics BFN–ferrite composite

ρ [g/cm3] 6.34 6.60ρDC × 10−6 at Tr [Ωm] 8.23 1.53Tm [°C] (1 kHz) 247 235εr (1 kHz) 270 2740εm (1 kHz) 39,100 71,280tanδ at Tr (1 kHz) 2.07 1.37tanδ at Tm (1 kHz) 2.58 2.07MS [emu/g] at Tr – 7.15ΔEτ [eV] 0.204 0.191τ0 × 109 [s] 4.89 5.68

Fig. 12 – Magnetization temperature dependencies ofBFN–ferrite composite sintered at a temperature of 1350 °C(a), magnetic hysteresis loops at temperatures: −271 °C,−173 °C and 27 °C (b).

43M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

the phenomena related to momentum rotations of particularareas of spontaneousmagnetizationwhich approach to positionthemselves in parallel to the direction of magnetic field(the sample's magnetization changes are irreversible), show

Fig. 13 – The Mössbauer spectru

predominance. Saturation is achieved in a proper HS field. Theforegoing phenomena overlap in ferromagnetic materials, andtheir character is strongly related to the structural properties ofthe ferromagnetic material. For the ceramic BFN–ferrite com-posite, with the increase of temperature themagnetic saturationof hysteresis loop and the value of spontaneous magnetizationMS decreases (Fig. 12b). The steepest parts of the M(H) diagramcurves correspond to the process of rotation in the spontaneousmagnetization areas. The BFN–ferrite composite values of HC

coercive field are very low and with the increase of temperaturethey decrease insignificantly (μ0HC = 0.016 T for −271 °C, μ0HC =0.012 T for −171 °C and μ0HC = 0.007 T for 27 °C). With theincrease of temperature, spontaneous polarization also de-creases (MS = 9.88 emu/g for −271 °C, MS = 9.16 emu/g for−171 °C and MS = 7.22 emu/g for 27 °C). For the BFN ceramics,the magnetic hysteresis loop is of a different shape [14].

Mössbauer investigations of the composite BFN–ferriteperformed at room temperature in the transmission geometry(Fig. 13 and Table 2) indicate the presence of three absorptioncross-sections originating from the ferrite, BFN phase andsome additional components due to the minor impurityphase. Magnetically split spectral component is generated bythe Fe3+ high spin ion. This ion is located in the ferrite and ithas high crystallographic local symmetry, as the electricquadrupole interaction is negligible.

A dominance spectral doublet originates from the paramag-netic BFN phase with lower symmetry around iron generatingquadrupole splitting. The ionic state of iron is Fe3+ with high spinon this site. Prior to annealing, the mixture of BFN phase andferrite (90 wt.% of BaFe0.5Nb0.5O3 and 10 wt.% of Ni0.63Zn0.37Fe2O4)contained 67 at.% of iron in BFN and 33 at.% of iron in ferrite.Mössbauer result indicates that after annealing the iron distribu-tion is as follows: 65 at.% in BFN (Fe3+), 33 at.% in ferrite and2 at.% in impurity phase. Hence, the iron isn't transferred fromferrite to BFN phase during annealing.

4. Conclusion

The ferroelectromagnetic BaFe0.5Nb0.5O3 ceramics are analternative material for PbFe0.5Nb0.5O3 ceramics, which ex-hibits ferroelectric and magnetic properties. BFN also exhibits

m of composite BFN–ferrite.

Table 2 – The values of hyperfine parameters (IS, QS, Bhf)and A for BFN–ferrite composite, where: A — contributionof the respective sub-profile (phase/iron site) to the totalabsorption profile; IS — isomeric shift; QS — quadrupolesplitting; Bhf — hyperfine magnetic field. Errors for allvalues are of the order of unity for the last digit shown.

A [%] IS [mm/s] QS [mm/s] Bhf [T]

Ferrite 33 0.29 – 46.8BFN 65 0.43 0.55 –Impurity phase 2 0.30 2.35 –

44 M A T E R I A L S C H A R A C T E R I Z A T I O N 8 7 ( 2 0 1 4 ) 3 6 – 4 4

ferroelectric properties connected with the occurrence ofcharacteristic frequency dispersion with high values ofelectric permittivity.

The multiferroic ceramic BFN–ferrite composite possessesgoodmagnetic parameters: high values ofmagnetization, narrowmagnetic hysteresis loop of low losses and of high saturationinduction. The aforementioned properties are characteristic ofthe soft ferromagneticmaterial. TheX-ray analysis confirmed thepresence of phases from the ferroelectromagnetic (BFN) andmagnetic (ferrite) components (no foreign phases present).Detailed Mössbauer analysis showed, however, trace amountsof another phase (containing iron) in an amount of 2.0%.

The microstructural research revealed the presence of smallferrite grains surrounded by much larger ferroelectromagneticcomponent grains in the fracture.

In comparison with BaFe0.5Nb0.5O3, dielectric loss in thetwo-phase ceramic BFN–ferrite composite decreases yet is stilltoo high. In order to reduce them, doping of ions of elementsof small ionic radius (e.g. lithium or chromium) to the basiccomponent of the composite (BFN) appears to be necessary.The optimization of the two-phase BFN–ferrite compositionand research in this direction will be continued (also in orderto increase the competitiveness of the ceramic BFN–ferritecomposite in magnetoelectric transducers).

R E F E R E N C E S

[1] Bochenek D, Surowiak Z. Influence of admixtures on theproperties of biferroic Pb(Fe0.5Nb0.5)O3 ceramics. Phys StatusSolidi A 2009;206(12):2857.

[2] Surowiak Z, Bochenek D. Multiferroic materials for sensors,transducers andmemory devices. Arch Acoust 2008;33(2):243.

[3] Raymond O, Font R, Portelles J, Siqueiros JM. Magnetoelectriccoupling study inmultiferroic Pb(Fe0.5Nb0.5)O3 ceramics throughsmall and large electric signal standardmeasurements. J ApplPhys 2011;109:094106.

[4] Bochenek D, Guzdek P. Ferroelectric and magnetic propertiesof ferroelectromagnetic PbFe1/2Nb1/2O3 type ceramics. J MagnMagn Mater 2011;323:369.

[5] Liou Yi-Cheng, Shih Yi-Che, Chuang Cheng-Jung. PZN–PFWand PFN–PFW relaxor ferroelectric ceramics by areaction-sintering process. J Electroceram 2004;13:457.

[6] Raevskiï IP, Eremkin VV, Smotrakov VG, Malitskaya MA,Bogatina SA, Shilkina LA. Growth and study of PbFe1/2Ta1/2O3

single crystals. Crystallogr Rep 2002;47(6):1007.[7] Bochenek D, Dudek J. Influence of the processing conditions

on the properties of the biferroic Pb(Fe1/2Nb1/2)O3 ceramics.Eur Phys J Spec Top 2008;154:19.

[8] Bochenek D, Kruk P, Skulski R, Wawrzała P. Multiferroicceramics Pb(Fe1/2Nb1/2)O3 doped by Li. J Electroceram2011;26:8.

[9] Scott JF. Applications of magnetoelectrics. J Mater Chem2012;22:4567.

[10] Kruea–In C, Eitssayeam S, Pengpat K, Rujijanagul G. Highdielectric constant observed in(1 − x)Ba(Zr0.07Ti0.93)O3-xBa(Fe0.5Nb0.5)O3 binarysolid-solution. Mater Res Bull 2012;47:2859.

[11] Nogas–Ćwikiel E. Ceramics with tetragonal tungsten bronzetype structure for textured ceramics–polymer composites.Ferroelectrics 2011;418(1):28.

[12] Bartkowska JA. Dynamical magnetoelectric coupling inmultiferroic BiFeO3. Int J Thermophys 2011;32(4):739.

[13] Dercz J, Starczewska A, Dercz G. Dielectric and structuralproperties of Bi5Ti3FeO15 ceramics obtained by solid-statereaction process from mechanically activated precursors. IntJ Thermophys 2011;32(4):746.

[14] Bochenek D, Surowiak Z, Poltierova–Vejpravova J. Producingthe lead-free BaFe0.5Nb0.5O3 ceramics with multiferroicproperties. J Alloys Compd 2009;487:572.

[15] Ganguly M, Parida S, Sinha E, Rout SK, Simanshu AK, HussainA, et al. Structural, dielectric and electrical properties ofBaFe0.5Nb0.5O3 ceramic prepared by solid-state reactiontechnique. Mater Chem Phys 2011;131(1–2):535.

[16] Singh NK, Kumar P, Rai R. Study of structural, dielectric andelectrical behavior of (1 − x)Ba(Fe0.5Nb0.5)O3-xSrTiO3

ceramics. J Alloys Compd 2011;509:2957.[17] Rama N, Philipp JB, Opel M, Chandrasekaran K,

Sankaranarayanan V, Gross R, et al. Study of magneticproperties of A2B NbO6 (A = Ba, Sr, (BaSr) and B = Fe and Mn)double perovskites. J Appl Phys 2004;95(11):7528.

[18] Saha S, Sinha TP. Structural and dielectric studies of BaFe0.5Nb0.5O3. J Phys Condens Matter 2002;14:249.

[19] Wójcik K, Zieleniec K, Mulata M. Electrical properties of leadiron niobate PFN. Ferroelectrics 2003;289:107.

[20] Eitssayeam S, Intatha U, Pengpat K, Tunkasiri T. Preparationand characterization of barium iron niobate (BaFe0.5Nb0.5O3)ceramics. Curr Appl Phys 2006;6:316.

[21] Prabakar K, Mallikarjun Rao SP. Complex impedancespectroscopy studies on fatigued soft and hard PZTceramics. J Alloys Compd 2007;437:302.

[22] Zhang H, Chee–Leung M. Impedance spectroscopiccharacterization of fine-grained magnetoelectricPb(Zr0.53Ti0.47)O3–(Ni0.5Zn0.5)Fe2O4 ceramic composites. JAlloys Compd 2012;513:165.

[23] Ahn JH, Lee J-U, Kim TW. Impedance characteristics ofITO/Alq3/Al organic light-emitting diodes depending ontemperature. Curr Appl Phys 2007;7:509.