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A detailed study was carried out to investigate the effects of poling on structure, vibrational, dielectric, and ferroelectric properties of donor-doped (V5+ at Ti4+-site) lead-free Na0.47Bi0.47Ba0.06Ti(1-x)VxO3, (x =0, 0.01, and 0.03) ceramics fabricated via a modified sol-gel method. Rietveld refinement of synchrotron radiation source powder x-ray diffraction data showed that unpoled samples are in rhombohedral R3c phase whereas poled samples showed a mix rhombohedral R3c and tetragonal P4mm phases at ambient temperature, due to a long-range order established in lattice system after poling. V+5 doping increases the rhombohedral distortion in unpoled and poled samples while it reduces the tetragonality in poled samples. Vibrational study revealed that unpoled samples have more lattice disorder compared to poled samples. X-ray absorption near edge spectroscopy measurement confirmed that Ti and V are in 4+ and 5+ oxidation states, respectively, for all poled and unpoled samples. The average grain size was found to decrease from 5.6 ± 0.5 μm for x =0 to 1.0 ± 0.2 μm for x =0.03. Depolarization temperature was found to increase significantly in poled samples from ∼104 °C for undoped sample to 150 °C for the sample with 1% vanadium substitution. Drastic improvements in ferroelectric and dielectric properties are explained in terms of structural changes. High remnant polarization Pr ∼ 31.4 μC/cm2 and moderately low coercive field Ec ∼ 20 kV/cm have been observed at an applied electric field of ∼35 kV/cm for the sample with 1% vanadium substitution which makes it an attractive candidate for ferroelectric applications. [ABSTRACT FROM AUTHOR]

This paper presents the results of a comprehensive study of the industrially produced ferro-piezoelectric ceramic material based on the PbZrO3-PbTiO3- PbMn 1 ∕ 3 Nb 2 ∕ 3 O3- PbZn 1 ∕ 3 Nb 2 ∕ 3 O 3 + SiO 2 system. Studies have confirmed that this material refers to ferro-rigid materials with high coercive fields, stable dielectric properties in a wide temperature range, practically no Curie temperature hysteresis, as well as low controllability of the dielectric constant and deformation characteristics by constant bias electric fields. The revealed correlation between dielectric, deformation characteristics and dielectric hysteresis allows us to consider this material as promising for devices operating in power modes: piezotransformers, highly loaded ultrasonic devices, piezoelectric motors, etc. [ABSTRACT FROM AUTHOR]

(Ba 0.7 Ca 0.3 )Ti 1- x Cu x O 3- x ceramics (where x  = 0, 0.01, 0.02 and 0.03) were prepared employing a conventional solid state sintering technique. X-ray diffraction patterns and Ti K-edge X-ray Absorption Near-Edge Structure (XANES) spectra indicated a structural distortion of Cu-doped ceramics. Depending on Cu content, the features of normal ferroelectric and diffuse dielectric phase transition could be induced by the Cu addition. The temperature where maximum dielectric existed was decreased upon increase of Cu concentration. The creation of oxygen vacancies and defect dipoles caused double-like P-E loop in host material. The decrease of d 33 , g 33 and k p values was observed in correlation with decrease of P r in doped ceramics. The results here suggested that the electrical properties of this ceramic system may be largely tunable by Cu dopant and could be an attractive material for high-dielectric response devices. [ABSTRACT FROM AUTHOR]

Novel temperature stable Li 3 Mg 2 NbO 6 -0.1TiO 2 (LMNT) ceramics doped with Li 2 O-B 2 O 3 -Bi 2 O 3 -SiO 2 (LBBS) glass were synthetized by a solid-state route. The sintering temperature of the LBBS glass doped LMNT ceramics can be effectively lowered to 900 °C. The experimental results revealed that the addition of the LBBS glass can assist to improve the Q × f values while shifting the τ f values toward negative direction. Particularly, the 1 wt% of LBBS glass doped LMNT ceramic sintered at 900 °C for 4 h possessed excellent microwave dielectric properties: ε r  = 16, Q × f = 42,648 GHz, τ f  = −1ppm/°C, which is potential for LTCC applications. [ABSTRACT FROM AUTHOR]

Lead free piezoelectric ceramics (1– x ) (0.67Bi 1.05 FeO 3 –0.33BaTiO 3 )– x LiNbO 3 with x = 0.00, 0.015 and 0.030 were prepared by using conventional mixed oxide route. The incorporation of LiNbO 3 into BF–BT system caused no significant change in crystal structure. However, an obvious variation in electrical properties was observed. The x = 0.015 composition showed enhanced ferroelectric and electric field-induced strain properties with dynamic piezoelectric constant S max / E max = 440 pm/V at a relatively low field of 40 kV/cm, along with a high working temperature upto T m = 392 °C. LiNbO 3 addition improved the temperature insensitivity of relative permittivity (ε r ) at high temperatures. At x = 0.030, a near-plateau ε r ∼5000, extended across the temperature range, 200 °C–500 °C was observed which is advantageous for temperature insensitive dielectric ceramics for high temperature capacitor applications. Large strain and almost temperature invariant ε r with high working temperature range makes this system suitable for high temperature electronic devices. [ABSTRACT FROM AUTHOR]

Developing Na 0.5 Bi 0.5 TiO 3 -based magnetoelectric (ME) coupling composites with higher depolarization temperature is highly valuable for the environment-friendly smart electronic devices. We have developed a new kind of 0-3 type 0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 : x CoFe 2 O 4 (NBTBT: x CFO, x = 0, 0.1, 0.2, 0.3) composite ceramics with a deferred depolarization temperature, together with an additional strong ME coupling of 9.2 mV/cm·Oe for the NBTBT:0.2CFO. The basic structure, ferroelectric/ferromagnetic properties, and the depolarization temperature of the NBTBT: x CFO composite ceramics were investigated. It was found that an enhancement of depolarization temperature (>25 °C) was obtained in these 0-3 type composites relative to the pure NBTBT ones (115 °C vs 90 °C). The mechanism of the enhanced depolarization temperature of the composites is discussed. The present results demonstrate that NBTBT: x CFO composites have great potential for ME devices. [ABSTRACT FROM AUTHOR]

Multifunctional ceramics with good dielectric, ferroelectric, piezoelectric and photoluminescence properties have been fabricated at a low sintering temperature of 960 °C. Via the addition of Li 2 CO 3 , oxygen vacancies are produced in the Pr-doped 0.93(Bi 0.5 Na 0.5 )TiO 3 -0.07BaTiO 3 ceramics, which can enhance the ionic lattice-diffusion coefficient, promote the densification and thus lower the sintering temperature effectively from 1200 to 960 °C. The Li-addition also induces lattice distortion and expansion, which strengthen the internal field among the polar nano-regions of the ceramic. As a result, the depolarization temperature is increased and the room-temperature piezoelectric properties are enhanced. Moreover, the structural symmetry is reduced, and thus leading to an increase in the uneven components of the crystal fields around Pr 3+ and then an enhancement in photoluminescence emissions. Together with the good dielectric properties assured by the dense structure, the ceramics are ready for use in multifunctional optoelectronic applications. [ABSTRACT FROM AUTHOR]

Li 2 CO 3 has been used as a sintering aid for fabricating lead-free ferroelectric ceramic 0.93(Bi 0.5 Na 0.5 TiO 3 )-0.07BaTiO 3 . A small amount (0.5 wt%) of it can effectively lower the sintering temperature of the ceramic from 1200 °C to 980 °C. Unlike other low temperature-sintered ferroelectric ceramics, the ceramic retains its good dielectric and piezoelectric properties, giving a high dielectric constant (1570), low dielectric loss (4.8%) and large piezoelectric coefficient (180 pC/N). The “depolarization” temperature is also increased to 100 °C and the thermal stability of piezoelectricity is improved. Our results reveal that oxygen vacancies generated from the diffusion of the sintering aid into the lattices are crucial for realizing the low temperature sintering. Owing to the low sintering temperature and good dielectric and piezoelectric properties, the ceramics, especially of multilayered structure, should have great potential for practical applications. [ABSTRACT FROM AUTHOR]

In this study, in order to develop relaxor ferroelectric ceramics with large electrocaloric effect, (Pb0.88La0.8)(Zr0.65Ti0.35)O3 ceramics were manufactured using conventional solid-state reaction method with the amount of ZnO addition. The XRD pattern of all specimens indicated general perovskite structure with secondary phase. With increasing the amount of ZnO addition, the coexistence of rhombohedral and tetragonal phases was observed. The temperature change ΔT of specimen exhibited the tendency to increase with the amount of ZnO addition. Furthermore, at the 0.6 wt% added ZnO ceramics, the optimal value of ΔT = 0.345°C in ambient temperature of 215°C was appeared. It is considered that (Pb0.88La0.08)(Zr0.65Ti0.35)O3 ceramics show the possibility of refrigeration device application. [ABSTRACT FROM AUTHOR]

Compositions in the solid solution series (1-x)(Bi 0.5 Na 0.5 ) 0.935 Ba 0.065 Ti–x(LiSbO 3 ), (BNBT-LS) (x = 0, 0.01, 0.02, 0.03, 0.04) have been fabricated via solid state reaction route. Room temperature x-ray diffraction traces of all samples were found to reveal coexistence of the two structures; rhombohedral and tetragonal. The micrographs recorded from the Field Emission Scanning Electron Microscope, provided an overall dense and single phase microstructure for the systems. The dielectric anomalies corresponding to the maximum relative dielectric constant, ε r , persistently broadened and shifted to low temperatures as a function of increase in LiSbO 3 (LS) content. The ferroelectric P − E loops became steadily narrow with similar LS modification showing a continual decline in remnant polarization ( P r ) and coercive field ( E c ) . These phenomena clearly indicated the onset of a growing relaxor-like behavior. The maximum normalized unipolar strain S max / E max = d 33 * = 400 pm / V under the field 50 kV/cm was recorded for the system with x = 0.02. [ABSTRACT FROM AUTHOR]

The influence of the electronegativity of phases, which is controlled by composite crystallization under the conditions of the effect of the electric discharge and covalence of piezophase cations, on the formation mechanism of the stable electret effect is determined. The specific features of the formation of the electret effect in composites based on polyolefins (HDPE, PP), fluorine-containing polymers (F42), and ferroelectric piezoelectric ceramics of the family of lead zirconate-titanate (Pb(Zr,Ti)O) crystallized under conditions of the effect of electric discharge plasma, are revealed. A physical model of electret composites taking into account the role of homocharges and heterocharges formed in a composite by its dispersion with piezoceramic particles of various structures-rhombohedral, tetragonal, and heterogeneous-is proposed. [ABSTRACT FROM AUTHOR]

Multiferroic composites (1 − x ) BaTi 0.9 Zr 0.1 O 3 + ( x ) Li 0.5 Fe 2.5 O 4 ( x = 0.0, 0.05, 0.10 and 0.15) were synthesized using conventional solid state reaction method. The structural, morphological, functional groups, dielectric and magnetic properties of undoped and doped composites were studied by XRD, FESEM, FTIR, Impedance analyzer and VSM respectively. The magneto-electric voltage coefficient was measured using dynamic lock in technique. The XRD analysis confirmed the formation of tetragonal structure. The percentage of phases in the composites and ratio of c/a values are tabulated. The SEM images confirm the dispersion of Li 0.5 Fe 2.5 O 4 (LF) in BaTi 0.9 Zr 0.1 O 3 (BTZr). The formation of strong absorption bands in FTIR confirms the perovskite structure in unsubstituted BTZr. The dielectric constant increases with increase of Li 0.5 Fe 2.5 O 4 content. We have determined the transition temperature from the Magnetization – Temperature curves which vary between 331 K and 506 K. Electromagnetic coupling gives an interface between ferroelectric and magnetic phases due to strain observed by using magneto-electric properties. [ABSTRACT FROM AUTHOR]

Particulate magnetoelectric (ME) ceramics constituted by (1- x )(80Bi 0.5 Na 0.5 TiO 3 -20Bi 0.5 K 0.5 TiO 3 )- x CoFe 2 O 4 [(1- x )BNKT- x CFO] ( x = 0, 0.1, 0.2, 0.3, 0.4 and 1.0) were synthesized by an powder-in-sol precursor hybrid processing method and their structure, magnetic, ferroelectric, magnetodielectric (MD) and ME properties have been investigated. Results showed that the ceramics consisted of only two chemically separated phases and had homogeneous microstructure. The introduction of CFO into BNKT matrix led to the weakening of ferroelectric and dielectric properties whereas the strengthening magnetic and MD properties. The observation of the MD effect revealed the evidence of the strain-induced ME coupling and the MD value is well scaled with M 2 . A maximum value of ME output of 25.07 mV/cm·Oe was achieved for the 0.7BNKT-0.3CFO composite. The improved ME response together with the linear MD effect makes the ceramics promise for use in magnetic field controllable devices or magneto-electric transducers. [ABSTRACT FROM AUTHOR]

New relaxor ferroelectric ceramic perovskites C a 0.67 L a 0.22 T i ( 1 − x ) C r x O 3 (x = 0.15 and x = 0.2) ( C L T ( 1 − x ) C r x ) were prepared by solid state reaction route. X-Ray diffraction study suggested that these compounds crystallize with orthorhombic symmetry with Pnma space group. The microstructure study of sintered pellets revealed that the grains size decrease with the increase in doping concentration. The dielectric study showed two temperature anomalies that induced an improvement in piezoelectric applications. This study exhibits a relaxor behavior for all compositions with excellent properties. A high permittivity was around 25000 and Δ T r e l a x = 79 K for x = 0.15. The best way to characterize the degree of the dielectric relaxation for relaxor ferroelectrics was established using the Lorentz fit model. Dielectric modulus measurement showed three thermally-activated dielectric relaxations. The low-temperature relaxations R1 are related to the polaron relaxations which are due to the hopping holes. The high-temperature relaxations R2 and R3 are associated with the conductivity originating from the hopping motions of double ionized oxygen vacancies. [ABSTRACT FROM AUTHOR]

In this study, we prepared the bismuth layer-structured ferroelectric (BLSF)-type Bi 4 Ti 3 O 12 (BiT), Bi 3.25 La 0.75 Ti 3 O 12 (BLaT), and Bi 3.1 Nd 0.9 Ti 3 O 12 (BNdT) ceramics using the solid-state reaction method. The prepared ceramics were irradiated at room temperature by using a 60 Co gamma-ray source in a dose range of 0–3000 kGy with a dose rate of 10 kGy/h to compare the structure and electrical properties of the irradiated ceramics. The X-ray diffraction analysis shows that the BLSF structure was well formed in all ceramics without a secondary phase. There was no structural change such as grain size change and secondary phase formation despite the cumulative gamma-ray dose of 3000 kGy. A comparison of the electrical properties with gamma-ray irradiation shows that the BiT ceramics exhibits a larger reduction ratio compared to the BLaT and BNdT ceramics. The rate of change of the remnant polarization (2 P r ) value with the gamma-ray irradiation doses was − 14.2%, − 8%, and − 3.4% in BiT, BLaT, and BNdT ceramics, respectively, at a cumulative gamma-ray dose of up to 3000 kGy. Furthermore, the dielectric relaxation phenomenon in BiT ceramics at low frequency was observed when gamma rays of 1000 kGy or more were irradiated. Based on these results, in this study, we investigated the structure and electrical properties of BLSF ceramics with gamma-ray irradiation. [ABSTRACT FROM AUTHOR]

New ultra low-loss Li 6 Mg 7 Ti 3 O 16 (LMT) ceramics were prepared via the conventional solid-state reaction method. The crystal structure, sintering characteristics, infrared spectrum and microwave dielectric properties were studied. Rietveld refinement was performed to research the crystal structure and the lattice parameters were obtained. The microwave dielectric properties of the sintered samples exhibited the close relationship with the sintering characteristics. The bond energy of the LMT ceramics was calculated to analyze the intrinsic factors. The major polarization contribution was mainly dependent on the absorption of phonon oscillation. The ceramics sintered at 1550 °C exhibited the excellent properties of ε r = 15.27, Q·ƒ = 209,400 GHz and τ f = − 11.32 ppm/°C. [ABSTRACT FROM AUTHOR]

Ba 0,95 Sr 0,05 (Ti 0,95 Zr 0,05 ) 1-x Sn x O 3 (x = 0 and x = 0.025) ceramics were prepared by solid state method. We have systematically studied the effects of a low quantity of Sn substitution on the crystal structure, dielectric and electrocaloric properties. X-ray diffraction shows that the symmetry of the two compositions x = 0 (BSTZ) and x = 0.025 (BSTZS) is both tetragonal with a space group P 4 mm and orthorhombic with Pmmm space group. Dielectric measurements show that Sn doping significantly reduces the Curie temperature from 392 K for BSTZ to 364 K for BSTZS. A typical hysteresis loops were observed for the investigated compositions and they were confirmed the ferroelectric-to-paraelectric transition phase. Finally electrocaloric effect in lead-free BSTZ and BSTZS ceramics is studied using an indirect method from the thermal variation of P-E hysteresis loops using the Maxwell relation. In the composition x = 0, the electrocaloric temperature ΔT was about 0.048 K. The addition of a low quantity of tin (Sn) ions in the matrix of Ba 0,95 Sr 0,05 (Ti 0,95 Zr 0,05 ) has been able to increase the electrocaloric temperature until ΔT reached 0.095 K to a field E = 1 kV/mm. [ABSTRACT FROM AUTHOR]

The effect of sintering temperature on structural, dielectric and ferroelectric properties of 0.80BaTiO3–0.20PbZrO3was investigated. The material was synthesized by solid-state reaction method and sintered at different temperatures like 1200, 1225, 1250, 1275 and 1300°C for 4 hours. All the samples were subjected to X-ray diffraction (XRD) analysis and found to have single phase orthorhombic perovskite structure. Dielectric behavior was studied as a function of frequency and temperature. The ferroelectric properties were also investigated by recording the PE hysteresis loops of all the samples at room temperature. [ABSTRACT FROM AUTHOR]

(PbBaLa)(ZrSnTi)O (PBLZST) antiferroelectric ceramic/conducting filler (carbon nanopowder, graphene nanosheets or carbon nanotubes)/polystyrene (PS) composites were prepared by solution-mixing method and molded by hot-pressing process. All composites exhibited high room-temperature tunability under low electric field (200 V/mm) due to the introduction of conducting filler, which increased the effective electric field applied on the ceramics particles. For different carbon conducting fillers, their shapes are different and thus they have different specific surface areas, resulting in different mass ratios for obtaining highest dielectric tunability. The maximum room-temperature dielectric tunability of three-phase composites with different conducting fillers were respectively 17.5% (1.0 wt% carbon nanopowder), 17% (0.4 wt% carbon nanotubes) and 20% (0.6 wt% graphene nanosheets) at 200 V/mm, which were two or three times of the tunability of PBLZST/PS composites without any conducting fillers. Besides, all composites showed low dielectric loss and permittivity that met the practical application requirements. All these make three-phase composites obtained in this work promising candidates for tunable devices application. [ABSTRACT FROM AUTHOR]

(Bi0.5Na0.4K0.1)Ti0.98Al0.02O3-δ(BNKT-A) and (Bi0.5Na0.4K0.1)Ti0.98Fe0.02O3-δ(BNKT-F) ceramics were prepared via a conventional solid-state reaction method. Microstructure and piezoelectric properties of the two ceramics were comparatively studied. Both the samples exhibit single-phase structures. There is no obvious change in microstructure between the two samples. The depolarization temperatures were estimated from dielectric spectra, change of piezoelectric constant with annealing temperature, and thermally stimulated depolarization current. Compared with BNKT-A, BNKT-F exhibits higher piezoelectric constant and higher depolarization temperature. The Rayleigh analysis exhibits that BNKT-F has higher extrinsic contribution from irreversible domain wall translation process compared with BNKT-A. [ABSTRACT FROM AUTHOR]

The ferroelectric phase transition of copolymers of vinylidene fluoride (VDF) with trifluoroethylene (TrFE) is well known and related to conformational changes in the polymer chain. Contrary to the expected paraelectric behaviour in the high temperature phase a pyroelectric investigation of the phase transition in the range from 0°C to 130°C combined with X-ray diffraction indicate the copolymer as ferroelectric when prepared and polarised in the high-temperature phase. Based on this finding the orthorhombic space-groupFmm2 is proposed for the polar high-temperature phase. Above the Curie temperature the material exhibits pyroelectricity with inverted sign, whose origin is interpreted as flexoelectricity. [ABSTRACT FROM AUTHOR]

(Pb0.87Ba0.10La0.02)(Zr0.60Sn0.40-xTix)O3(PLBZST) (x = 0–0.20) bulk ceramics were prepared by the conventional solid state method, and the dependence of phase transformation, ferroelectric properties and energy storage properties on x values has been investigated. When x = 0.12, the unit cell volume significant change indicted the phase transformation of the ceramics. As x = 0.04–0.10, the PLBZST ceramics possess anti-ferroelectric phase with high recoverable energy storage density 0.8–1.3 j/cm3and when x = 0.12–0.20, the ceramics with ferroelectric phase have lower density values about 0.2–0.3 j/cm3. The phase switching electric field, saturation polarization and test temperature have an important influence on energy storage density and efficiency. As a result, the PLBZST bulk ceramics exhibit the largest recoverable energy density of 1.3 j/cm3with efficiency of 77.4% at 20°C. [ABSTRACT FROM AUTHOR]

LiNbO3has been synthesized by solid state sintering technique. The glass 30Li2O: 50B2O3: 10 Nb2O5: 10SiO2has been synthesized by conventional quenching technique. Different weight percentage of glass was added into LiNbO3ceramics and sintered at different temperatures. The samples were characterized by using X-Ray Diffraction, Density and Scanning Electron Microscope. The dielectric and ferroelectric measurements of these ceramics suggests that the addition of glass has helped in improving its properties. The LiNbO3ceramic with 5 wt% glass addition has shown optimum properties among the ceramics prepared. [ABSTRACT FROM AUTHOR]

Ceramic samples Ca0.1Sr0.9R0.1Bi1.9Ta2O9(R=Nd, Pr & La) were prepared by solid state double sintering route. XRD data confirms single phase formation with orthorhombic structure at room temperature. SEM studies revealed polycrystalline nature with randomly oriented needle and plate like morphology for Nd and La doped CSBT ceramics. Dielectric studies were carried out as a function of temperature at different frequencies. Modified Lorentz equation which gives information about the thermally activated orientation of dipoles was used to describe the temperature dependence of dielectric data. The activation energy for thermally activated orientation of dipoles for the present ceramic samples was found to be in the range 60–130 μeV depending up on the type of rare earth ion substitution in CSBT. [ABSTRACT FROM AUTHOR]

BaPbO3(BPO) thin films of different thickness were deposited by pulsed laser deposition on p type Si/SiO2substrates. The influence of film thickness on the structural and electrical properties is studied. It is found that the BPO thin films of 300 nm has good crystallinity and grain size of 21nm. The carrier mobility increases with film thickness for films above 150 nm due to the ordered structure resulting in large grain size and small number of boundaries which enhances charge transport. The effect of BPO film thickness on the ferroelectric properties of Pb(Zr0.52Ti0.48)O3(PZT) thin films grown over BPO electrode were also investigated. Stress analysis on the thin films was carried out to investigate the dependence of BPO thickness on the ferroelectric properties of PZT. The mean grain size of PZT obtained by the Williamson – Hall Plots are 33, 45, 57 and 39 nm with increasing BPO film thickness. It was found that the Prvalues of PZT film deposited over BPO of thickness 225 nm is relatively large with low Ec. It is observed that stress and grain size effects have a competing effect. Larger grain size possess a decreased grain boundary density, which reduces the probability of space charge trapping at grain boundaries and facilitate effective domain mobility which result in the improvement of ferroelectric properties. [ABSTRACT FROM AUTHOR]

To get excellent electrical properties of lead-free piezoelectric ceramic (Ba0.85Ca0.15)(Zr0.08Ti0.9Sn0.02)O3[BCZTS], Bi2O3was doped to modify BCZTS. The microstructure, phases and electrical properties were investigated by XRD, SEM and ferroelectric test instrument, respectively. The experimental results indicate that the ceramics have pure perovskite structure with 0–0.08 wt.% Bi2O3, indicating that the Bi2O3diffused into the lattice of BCZTS. And when the content of Bi2O3reaches to 0.06 wt.%, homogenous microstructure and no pores can be found in ceramic. The ceramic has optimized properties ofd33= 430 pC/N,kp= 49.1%, ϵr= 3998, tan δ = 1.3%. Furthermore, the Curie temperature (Tc) increases firstly and then decreases as increasing the doping amount of Bi2O3. TheP-Eloops for the ceramics are observed and the value ofPrandEcis 8.08uC/cm2and 3.45 kV/cm under 35 kV/cm, respectively. [ABSTRACT FROM AUTHOR]

Barium-cobalt-bismuth-niobate, BaCoBiNbO (BCoBN) nanocrystalline ferroelectric ceramic was prepared through chemical route. XRD analysis showed single phase layered perovskite structure of BCoBN when calcined at 650 °C, 2 h. The average crystallite size was found to be 18 nm. The microstructure was studied through scanning electron microscopy. The dielectric and ferroelectric properties were investigated in the temperature range 50-500 °C. The dielectric constant and dielectric loss plot with respect to temperature both indicated strong relaxor behavior. Frequency versus complex impedance plot also supported the relaxor properties of the material. The impedance spectroscopy study showed only grain conductivity. Variation of ac conductivity study exhibited Arrhenius type of electrical conductivity where the hopping frequency shifted towards higher frequency region with increasing temperature. The ac conductivity values were used to evaluate the density of state at the Fermi level. The minimum hopping distance was found to be decreased with increasing temperature. [ABSTRACT FROM AUTHOR]

In this work, an electric field-induced giant strain response and electric displacement, as well as temperature-dependence dielectric, impedance and energy storage densities were studied in lead-free BNT-based ferroelectric system. The XRD analysis reveals that all the investigated ceramics have a pure perovskite structure. A maximum energy storage density up to 0.907 J/cm at 80 kV/cm is exhibited for (1− x) NaBiTiO- xBa(MgNb)O ceramics at an x of 0.07. Follow-up experiments confirm that an electric-field-induced phase transition, which results in giant strain up to 0.12% at 10 Hz, is also the origin of initially weak piezoelectricity. After doping a certain amount of Ba(MgNb)O, it is obvious that the dielectric peaks shift to low temperature and present dispersion characteristic. The increase in composition ( x) can suppress grain conductivity heavily in high temperatures, thus gives a way how to adjust the nominal BNT composition for the reduction of leakage conductivity. [ABSTRACT FROM AUTHOR]

The complex permittivity of bulk ceramic ferroelectric of nominal composition PbZr0.4Ti0.6O3was measured in the range 0.2–2 THz using transmission time-domain spectroscopy. The results indicate strong absorption and dispersion in this frequency range as often seen in highly disordered and polar materials. The results are compared to equivalent thin film data in the literature, and significant differences in the real and imaginary permittivity suggest that substrate clamping and degree of polarisation of the ferroelectric thin film materials affect dielectric properties even at these high frequencies. [ABSTRACT FROM AUTHOR]

(Bi 0.5 Na 0.5 ) 0.925 Ba 0.075 (Ti 1− x Mn x )O 3 ( x =0, 0.2, 1.0, and 2.0 mol%) ceramics were prepared by solid-state-reaction method to study dielectric, ferroelectric, and depolarization properties. The manganese (Mn) doping can suppress dielectric permittivity and increase relaxor behavior. Coercive field ( E c ) increases, while remanent polarization ( P r ) decreases as the Mn content increases. P r exhibits discontinuous anomalies as a function of temperature in all compositions, implying a polarization reorganization of local domains. The depolarization temperature ( T d ) reaches the highest value (~152 °C) in 0.2%Mn, and decreases as MnO 2 content increases. The increased T d in 0.2%Mn is due to two-phase coexistence and structural thermal stability induced by Mn ions. This work suggests that the moderate Mn doping can enhance T d in lead-free piezoceramics for applications at elevated temperatures. [ABSTRACT FROM AUTHOR]

The epitaxial growth of FeSi film on (001) 0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (PMN-0.32PT) was fabricated by sputtering and confirmed by high-resolution transmission electron microscopy. A fourfold symmetric angular remanent magnetization curve of as-deposited FeSi thin film is well fitted theoretically by considering the cubic magnetocrystalline anisotropy. We found that the fourfold anisotropy decreases slightly when an electric field (E) is applied on the Pt/PMN-0.32PT/FeSi/Ta heterostructures with Pt layer as the positive electrode. However, a magnetic anisotropy transition from fourfold anisotropy to twofold anisotropy occurs under negative E. The strain-electric field curve suggests that the observed different variation trend of magnetic anisotropy results from the asymmetric strain response on the polarity of E. Moreover, once the transition happens, it was irreversible unless the heterostructures are heated above the phase transition temperature of PMN-0.32PT. [ABSTRACT FROM AUTHOR]

Ferroelectric PZT-PVDF composites (0–3 connectivity) of specific dimensions were made utilizing a hot press technique. Linear variation in the experimental density of the pellets made from 0.1 to 0.8 PZT volume fraction was observed. The surface morphology of the composite has been micro-graphed using SEM. The variation of the dielectric properties of the composites on PZT volume fractions is reported and analyzed. It is observed that there was an increment in dielectric constant (ϵr) with an increase in temperature and volume fractions. The piezoelectric strain coefficient (d33) increases with an increase in the volume fraction and voltage coefficient (g33) were calculated. Comparisons were made with the Furukawa model to ϵrand d33. The remnant polarization and coercive field were analyzed from the hysteresis plots. [ABSTRACT FROM AUTHOR]

Dielectric response of Ba2NdFeNb4-xTaxO15(x = 0.3, 0.6 and 2) solid solutions with Tetragonal Tungsten Bronze structure has been investigated by means of broadband dielectric spectroscopy in the frequency range from 20 Hz to 37 GHz. Pure Ba2NdFeNb4O15compound displays ferroelectric behavior. Substitution of Nb5+by Ta5+considerably alters dielectric response of this system. Ferroelectric state was observed only for x = 0.3 compound with slightly lowered ferroelectric phase transition temperature. Further increase of x causes formation of relaxor state in these solid solutions and considerably lowers corresponding dielectric permittivity dispersion temperature region. [ABSTRACT FROM AUTHOR]

A study of photocurrent kinetics and dielectric response to infra-low frequencies in the range of the broad phase transition in the Ba0.25Sr0.75Nb2O6(BSN-75) relaxor ceramics under visible and ultraviolet radiation is reported. Anomalies are revealed in the dependence on field intensity of dielectric permittivity and dielectric loss determined from measurements of polarisation loops before and after illumination. The effects of pyro-electric space charge, polarisation and photovoltaic contributions on behaviour of the measured photocurrent are discussed. Results of the kinetics of photocurrent and dielectric response to infra-low frequency studied at different temperatures are discussed as the effects of non-equilibrium carriers on relaxation of polarisation. Kinetics of the photocurrent in ceramics and single crystals is found to be similar. [ABSTRACT FROM AUTHOR]

The (Ba1-xNax)(Ti1-xNbx)O3(BNTNx) ferroelectric ceramics have been prepared by a solid state reaction with the use of a conventional method. A mechanochemical treatment based on the high-energy planetary ball milling has been used as an alternative method of synthesizing of the ceramics. The morphology of the investigated samples was characterized by a scanning electron microscopy (SEM). The characterization of electrical properties of the BNTNx samples within the temperature range from 130 K to 600 K were performed by means of a dielectric spectroscopy method at the frequency ranging from 0.1 Hz to 10 MHz. The temperature and frequency dependences of real part of dielectric permittivity showed the changes of the character of the paraelectric–ferroelectric (PE–FE) phase transition for the ceramic samples obtained by both methods. These functional materials turned out to be either classical or relaxor ferroelectrics. [ABSTRACT FROM AUTHOR]

The relaxor behavior of barium zirconium titanate ceramics BaZr0.35Ti0.65O3prepared by a conventional sintering process was investigated. The synthesized material was determined by an X-ray diffraction and scanning electron microscopy. Based on performed studies, the BaZr0.35Ti0.65O3ceramic material has been identified as canonical relaxor, related to the Ti-rich polar regions. The freezing temperature Tfand activation energy Eaare calculated from the Vogel-Fulcher relationship. [ABSTRACT FROM AUTHOR]

SrMnO3ceramic was prepared by conventional high-temperature sintering method. Dielectric studies were performed within the temperature range 125–300 K at the frequency 10–400 kHz. The electronic properties of stoichiometric and oxygen defected SrMnO3crystal in hexagonal 6H- P63/mmc symmetry at 0 K were calculated inab initioprocedure based on density functional theory using the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) code. The lattice parameters and density of states were obtained. The ideal 6H-SrMnO3crystal has the band gap energy about 0.2–0.3 eV at 0 K. Contribution of an exchange-correlation energy into the total energy is about 32%, a magnetic moment about 3 µB. [ABSTRACT FROM AUTHOR]

[(Na0.5Bi0.5TiO3)0.7Sr0.3]1-xPrxTiO3(NBTS30P) (0 ≤ x ≤ 0.025) ceramics were prepared by solid-state synthesis process. Their crystal structure, microstructure dielectric and ferroelectric properties were studied. XRD data show that all of the ceramics possess a single perovskite phase. SEM results confirm that the ceramics are well sintered and exhibit relative densities higher than 97%. The results also reveal that the microstructure of the different compositions do not show a significant variation. The praseodymium (Pr) substitution to NBTS30 results in a change of crystal structure from cubic to tetragonal at x = 0.025. At the same time, electric permittivity decreases, the maximum is broadened and slightly shifted to lower temperature, polarization and coercive field decreases. It is also found that the frequency dependence of Tm(the temperature where electric permittivity is maximum) increases with increasing Pr. A possible origin for these observed effects is discussed. The results show that the investigated ceramics are promising lead-free materials for electronic applications. [ABSTRACT FROM AUTHOR]

The effect of partial replacement of Cu ions by small Be cations with no d-electrons in CaCu3Ti4O12ceramics was studied over the temperature range from 90 K to 800 K. Dielectric constant of CaCu3(1−x)Be3xTi4O12decreases exponentially with increasing x as ε′ =4000 + exp(-x/0.023); by 5% of Be-doping, the relaxation time and activation energy decrease to values of 50% and 92% compared with those in pure CCTO, respectively. The weakened hybridization in Cu-O bonds by Be-doping suppresses dielectric properties. This evidence indicates that the role ofA′-site ions is important for anomalous dielectric response in CaCu3Ti4O12at high temperatures. [ABSTRACT FROM AUTHOR]

The external stress (0–1500 bar) dependence of dielectric properties and an aging effect of BiFeO3ceramic has been investigated. The electric permittivity and dielectric losses first increased (up to about 700 bar) and next decreased with uniaxial pressure applied parallel to the ac field direction, while increased with the stress perpendicularly applied. It was suggested that combination of the de-aging, clamping of the domain walls, and the polarization reorientation mechanisms can be responsible for these changes. The aging effect is followed logarithmic law and is related to the relaxation of the domain structure towards an equilibrium configuration. [ABSTRACT FROM AUTHOR]

By the method of dielectric spectroscopy the complex oxides of bismuth titanate with a structure of layered perovskite doped by Cr in accordance with the stoichiometric formulas Bi4Ti2.98Cr0.02O11.99, Bi4Ti2.5Cr0.5O11.75, Bi4Ti1.8Cr1.2O11.4were studied. Shown the existence a critical concentration x (0.5

The influence of the low-melting KCl/LiF additive with molar ratio 80:20 on the structure, dielectric and ferroelectric properties of solid solutions with compositions close to morphotropic phase boundary in the (1−x)BiScO3- xPbTiO3system withx=0.635 (BSPT1) andx=0.645 (BSPT2) doped by 5, 10 and 15 w. % of KCl/LiF has been studied. Dense single phase ceramic samples have been prepared at 1313 – 1323 K (2 h) using as initial the BSPT1 and BSPT2 powders prepared from nitrate solutions. Addition of KCl/LiF led to displacement of BSPT1 and BSPT2 compositions from the initial mixture of rhombohedral and tetragonal phases to the region of the tetragonal one. This effect was accompanied by a small increase in the Curie temperatureTCvalue from 668 to 705 К in case of BSPT1 and from 672 to 714 К in case of BSPT2. Effects of additives on unit cell parameters of perovskite solid solutions, decrease in sintering temperatures, and improvement of the ceramic samples density were also found. [ABSTRACT FROM AUTHOR]

This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Leadfree 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 (BNT-BT-ST) bulk ferroelectric ceramic was selected for the course of investigation. 3BaO-3TiO2-B2O3 (BTBO) glass was then incorporated systematically to create sintered samples containing 0%, 2%, 4% and 6% glass (by weight). Upon glass induction features like remnant polarization, saturation polarization, hysteresis losses and coercive field could be varied as a function of glass content. Such effects were observed to benefit derived applications like enhanced energy storage density ~174 kJ/m³ to ~203 kJ/m³ and pyroelectric coefficient 5.7x10-4 Cm-2K-1 to 6.8x10-4 Cm-2K-1 by incorporation of 4% glass. Additionally, BNT-BT-ST depolarization temperature decreased from 457K to 431K by addition of 4% glass content. Glass incorporation could systematically increases diffuse phase transition and relaxor behavior temperature range from 70 K to 81K and 20K to 34 K, respectively when 6% and 4% glass content is added which indicates addition of glass provides better temperature stability. The most promising feature was observed to be that of dielectric response tuning. It can be also used to control (to an extent) the dielectric behavior of the host ceramic. Dielectric permittivity and losses decreased from 1278 to 705 and 0.109 to 0.107 for 6% glass, at room temperature. However this reduction in dielectric constant and loss increases pyroelectric figures of merit (FOMs) for high voltage responsivity (Fv) high detectivity (Fd) and energy harvesting (Fe) from 0.018 to 0.037 m²C-1, 5.89 to 8.85 μPa-1/2 and 28.71 to 61.55 Jm-3K-2, respectively for 4% added ceramic-glass at room temperature. Such findings can have huge implications in the field of tailoring ferroelectric response for application specific requirements. [ABSTRACT FROM AUTHOR]

CaCuTiO (CCTO) powders derived from sol-gel precursors were calcined and sintered via microwave radiation. The obtained CCTO powders were compared with that obtained via a conventional heating method. For microwave heating, 89.1 wt.% CCTO was achieved from the sol-gel precursor, after only 17 min at 950°C. In contrast, the conventional calcination method required 3 h to generate 87.6 wt.% CCTO content at 1100°C. In addition, the CCTO powders prepared through 17 min of microwave calcination exhibited a small particle size distribution of D = 3.826 μm. It was found that a lengthy hold time of 1 h by microwave sintering is required to obtain a high dielectric constant (3.14 × 10 at 10 Hz) and a reasonably low dielectric loss (0.161) in the sintered CCTO ceramic. Based upon the distinct microstructures, the dielectric responses of the CCTO samples sintered by different methods are attributed to space charge polarization and internal barrier layer capacitor mechanism. [ABSTRACT FROM AUTHOR]

An electro-mechanically coupled phase field model for ferroelectric domain evolution is introduced. Based on Gurtin's concept of a microforce balance, a generalized Ginzburg-Landau evolution equation is derived from the second law of thermodynamics. The thermodynamic potential is formulated for transversely isotropic material behavior by adopting a coordinateinvariant formulation. The model is reduced to 2D and implemented into a finite element framework. The numerical simulations concern the microstructure evolution in mechanically clamped BaTiO3 single-crystals. In the second part of this contribution Keip et al. [1], the poling behavior of ferroelectric composites and polycrystals is investigated with regard to size effects and the influence of a discontinuous order parameter field across grain boundaries. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We present a study on the ferroelectric phase transition, pyroelectric properties, and conduction mechanism of highly crystallized strontium orthovanadate (SrVO) ceramic, prepared by a solid-state reaction technique. X-ray diffraction studies show the formation of a single-phase compound in trigonal crystal system. Detailed studies of dielectric parameters ( ε and tan δ) of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and frequency. An anomaly in ε suggests the possible existence of a ferroelectric-paraelectric phase transition of diffuse type in the material, which is confirmed by electric polarization and pyroelectric studies. The low dielectric loss and moderate relative permittivity make this material (with suitable modifications) a potential candidate for use in microwave applications. The low leakage current and negative temperature coefficient of resistance (NTCR) behavior of the sample have been verified from J- E plots. The nature of the variation of the direct-current (DC) conductivity with temperature confirms the Arrhenius and NTCR behavior of the material. [ABSTRACT FROM AUTHOR]

A study of dielectric response to weak and strong measuring fields at temperatures of the diffuse phase transition in lead-magnesium niobate—lead-nickel niobate (PMN-PNN) containing an admixture of lithium is reported. A relaxor behaviour of the ceramic compound manifesting itself by a substantial shift of the temperature of dielectric permittivity maximum with field intensity and frequency is detected. Specific features of the dielectric nonlinearity observed at temperatures considerably higher than the temperature of the low-frequency dielectric permittivity maximum are related to extension of the range of phase transition to higher temperatures. This extension is related to formation of nano-size polar clusters within the region of the diffuse phase transition, the cluster formation being substantially affected by the applied field. [ABSTRACT FROM PUBLISHER]

The lead magnesium niobate-lead titanate ceramics are extensively use due to their excellent dielectric properties. The relaxor ferroelectric ceramic 0.9Pb(Mg2/3Nb1/3)O3-0. 1PbTiO3(0.9PMN-0.1PT) was fabricated through two steps method. The dielectric properties, dielectric constant and loss dependent on temperature, pyroelectric, were experimentally investigated. The results show that the dielectric constant-temperature curve obey the modified C-W law by Uchino and Nomural. The 0.9PMN-0. 1PT ceramic reveal strong dielectric relaxor behavior, wide dielectric peak, strong frequency dispersion, and the peak temperature Tm shift to higher with the frequency increasing, the relaxor factor is 1.89. The pyroelectric curve change slowly and continuously release charges during whole heating process. The pyroelectric coefficient is 100pC·m-2K-1 inroom temperature. [ABSTRACT FROM AUTHOR]

BaSrTiO (BST) for x = 0.20, 0.25 and 0.30 and LaSrMnO (LSMO) are synthesized using hydroxide co-precipitation route to lead to nanocrystalline particles of BST and LSMO respectively. Further the magnetoelectric (ME) and magnetodielectric (MD) composites of BST0.20, BST0.25 and BST0.30 are formed by addition of the LSMO at y = 0.1 and y = 0.2. The parent BST compositions are studied for its dielectric properties as a function of temperature and frequency up to 1 MHz. The AC conductivity of LSMO-BST (LBST) is studied and it confirms the conduction to be due to small polarons. The paper also presents ME and MD properties of LBST composites. The observation on MD properties show that the dielectric constant possesses contribution due to magnetic field dependant interfacial polarization and variation due to the stress induced because of the applied magnetic field. Further from the ME study, the maximum value of magnetoelectric coefficient is 15.51 mV/Oe/cm is observed for LBST composites. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lead free Ba0.8Ca0.2Ti0.8Ge0.2O3 ceramics. [•] Dielectric and ferroelectric properties. [•] Low coercive field for polarization switching. [•] Change of the nature of BaTiO3 phase transition by co-doping. [Copyright &y& Elsevier]