Ferroelectric Nature Research Articles

고온 진동 센서용 BiFeO3-BaTiO3 압전세라믹의 나노 BaTiO3 모분말 도입에 따른 화학적 불균일성 및 압전 특성 연구

1 mol% MnO₂-doped 0.7BiFeO₃-0.3BaTiO₃ (BFO-BTO) piezoceramics were synthesized through a conventional solid-state method, using nano-sized BaTiO₃ raw powders. In the application of the nano-BaTiO₃ raw powders, the phase structure, chemical heterogeneity, microstructure, ferroelectric, and piezoelectric properties significantly changed, compared to the application of conventional micron-sized BaCO₃ and TiO₂ raw powders. The sintered BFO-BTO piezoceramics showed a reduced chemical heterogeneity and strong ferroelectric nature, whereas the counterparts using the conventional micron-sized raw powders typically exhibited a core-shell structure with a high degree of chemical heterogeneity, causing a relaxor characteristic. In addition, the piezoceramics sintered using the nano-sized BaTiO₃ exhibited greater piezoelectric, ferroelectric and insulating properties, compared to those of ceramics sintered using the conventional micron-sized raw powders. The property enhancements of the BFO-BTO piezoceramics were attributed to the effects of reduced chemical heterogeneity, large grain size, low leakage current and the formation of appropriate morphotropic phase boundary. Finally, the achieved high TC of 519.1 °C and excellent thermal aging resistance of d33 up to 480 °C indicate great potential for use in high-temperature environments.

A Ferroelectric Aminophosphonium Cyanoferrate with a Large Electrostrictive Coefficient as a Piezoelectric Nanogenerator.

Hybrid materials possessing piezo- and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A3 BX6 type cyanometallate [Ph2 (i PrNH)2 P]3 [Fe(CN)6 ] (1), which shows a ferroelectric saturation polarization (Ps ) of 3.71 μC cm-2 . Compound 1 exhibits a high electrostrictive coefficient (Q33 ) of 0.73 m4 C-2 , far exceeding those of piezoceramics (0.034-0.096 m4 C-2 ). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt % 1-TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 μW cm-2 .

A Ferroelectric Aminophosphonium Cyanoferrate with a Large Electrostrictive Coefficient as a Piezoelectric Nanogenerator

AbstractHybrid materials possessing piezo‐ and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A3BX6 type cyanometallate [Ph2(iPrNH)2P]3[Fe(CN)6] (1), which shows a ferroelectric saturation polarization (Ps) of 3.71 μC cm−2. Compound 1 exhibits a high electrostrictive coefficient (Q33) of 0.73 m4 C−2, far exceeding those of piezoceramics (0.034–0.096 m4 C−2). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt % 1‐TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 μW cm−2.

Absence of presumed ferroelectricity in methylammonium lead chloride single crystals representing organic-inorganic hybrid perovskites

The performance of organic-inorganic metal halide perovskites as photovoltaics has been exceptional over the last decade, which is attributed to their unique properties like high absorption coefficient, tunable band gap, high conversion efficiency and a lot more. It is believed that the presence of ferroelectricity in the system assists charge separation leading to an increase in their efficiency. Many researchers have also claimed them to be ferroelectrics. However, there is debate among the researchers about their structures at different temperatures which questions their polar or non-polar nature and hence the presence of ferroelectricity in them. In the present study, this controversy over ferroelectric behavior of hybrid perovskites has been addressed, on MAPbCl3 single crystals. Through temperature dependent x-ray diffraction, Raman spectroscopy, dielectric permittivity, P-E (Polarization versus electric field) and PUND (Positive up negative down) measurements, it has been shown that the organic inorganic metal halide sample, MAPbCl3, is not ferroelectric and the structure is non-polar in the entire studied temperature range. These results will help in resolving the controversy present in the existing literature regarding the ferroelectric nature of organic inorganic metal halide perovskites MAPbX3 with X as Cl, Br or I.

NiTiO3/MnFe2O4 ferrite composites: synthesis, optical, ferroelectric and magnetic properties

Abstract This work reported the successful synthesis of ilmenite-spinel (1 − x)NiTiO3-xMnFe2O4 (x = 0, 0.05 and 0.10) composites by a simple sol-gel method. Phase formation of composites was analyzed by the X-ray diffraction method. All the synthesized samples formed diphasic ilmenite-ferrite composites without any trace of impurity or intermediate phase. The optical properties of synthesized composites were characterized by diffuse reflectance UV–visible spectroscopy. MnFe2O4 phase modified the optical band gap of NiTiO3 material and shifted its optical bandgap value toward lower energy. Ferroelectric and magnetic hysteresis loops were investigated at room temperature. The hysteresis loops indicated the typical ferromagnetic and ferroelectric nature of all composites at room temperature. In P-E loops, the remanent polarization (Pr ) and saturation polarization (Ps ) showed a slight increase in the sample with 5% MnFe2O4 phase addition. However, the lossy P-E loop was observed in the sample with the addition of 10% MnFe2O4. The presence of ferrite MnFe2O4 phase in NiTiO3 material enhanced the magnetic properties of NiTiO3 at room temperature. The M-H loops of NiTiO3-MnFe2O4 composites presented a ferromagnetic behavior with a dramatic increase in saturation magnetization with an increase of ferrite phase addition.

Superconductivity enhancement in polar metal regions of Sr0.95Ba0.05TiO3 and Sr0.985Ca0.015TiO3 revealed by systematic Nb doping

Two different ferroelectric materials, Sr0.95Ba0.05TiO3 and Sr0.985Ca0.015TiO3, can be turned into polar metals with broken centrosymmetry via electron doping. Systematic substitution of Nb5+ for Ti4+ has revealed that these polar metals both commonly show a simple superconducting dome with a single convex shape. Interestingly, the superconducting transition temperature Tc is enhanced more strongly in these polar metals when compared with the nonpolar matrix Sr(Ti, Nb)O3. The maximum Tc reaches 0.75 K, which is the highest reported value among the SrTiO3-based families to date. However, the Tc enhancement is unexpectedly lower within the vicinity of the putative ferroelectric quantum critical point. The enhancement then becomes much more prominent at locations further inside the dilute carrier-density region, where the screening is less effective. These results suggest that centrosymmetry breaking, i.e., the ferroelectric nature, does not kill the superconductivity. Instead, it enhances the superconductivity directly, despite the absence of strong quantum fluctuations.

Synthesis–dependent morphological, structural and photophysical properties of semicrystalline KNbO3:SiO2 hybrid silicates

Polycrystalline ceramics of KNbO3 (KNO) were prepared via sol–gel (by acrylamide polymerization), hydrothermal, and solid–state chemistry reactions. Pure orthorhombic perovskite phases crystallized in the Cm2m (38) space group were attained in all cases. Average crystallite sizes ranging 33–44 ​nm and grain structures varying from 350 to 580 ​nm were obtained depending on the implemented synthetic route. Prepared KNO compounds were embedded in porous a–SiO2 sonogel networks at different dopant rates to conform semicrystalline KNbO3:SiO2 hybrid silicates. Results evidence a clear dependence of the structural and optoelectronic properties of the composite glasses on the employed synthesis methodology. The massive porosity of the sonogel matrix and related defective bonding environment promoted strong intermolecular host–guest interactions influencing the electronic states, structural phase transitions, and Raman and luminescent features of the hybrid glasses via surface–assisted mechanisms and chemical charge–transfers. NLO/SHG activity was observed in all hybrid sonogels (HSG) due to the ferroelectric nature of KNO and the average macroscopic crystallite alignment attained along the polycondensation stage of the solid–solutions; where bulk NLO susceptibilities up to 9.10×10−11 ​esu and molecular hyperpolarizabilities in the 10−23 ​esu range, were estimated. Depending on the synthetic method and hybridized in–gap levels, bandgap energy narrowing was observed for the KNO/HSG systems, showing Eg values ranging 2.45–3.30 eV. A synergistic study comprising morphological, structural, spectroscopic, and quadratic NLO/SHG characterizations was performed to explore these novel composites’ structural and photophysical properties for Pb–free ferroelectric/optoelectronic composite applications.

A comprehensive study of structural, electrical and ferroelectric properties of NdFeO3-SnO2 nanocomposite

The NdFeO3-SnO2 nanocomposite was successfully prepared using a solid-state reaction route. The dual-phase (orthorhombic and tetragonal) in the NdFeO3-SnO2 composite was confirmed by XRD and then analyzed by Rietveld refinement. In the Raman spectrum, the A1g and B2g modes of SnO2 were observed at 650 cm−1, and 770 cm−1, and 7Ag and 1B1g modes of NdFeO3 were observed at 95 cm−1 and 650 cm−1. The Raman fingerprint modes provide good support for the formation of NdFeO3-SnO2 composite. The optical band gap evaluated by using defused reflectance spectroscopy of the as-prepared composite is found to be 3.60 eV. DC resistivity of the nanocomposite decreased with temperature and the sample exhibited the typical semiconducting behavior. The dielectric constant and dielectric loss decreased with frequency while increased with temperature. AC conductivity of the sample increases with the increase in frequency as well as temperature. P-E plots at different temperatures and electric fields reflected the well-known hysteresis loops and hence established the ferroelectric nature of the sample. The low leakage current of the sample observed in the I-E plot hints towards the possible use of this material in dielectric devices.

Investigations on the structural, electrical, magnetic and 57Fe Mössbauer studies of YFeO3

Yttrium iron oxide (YFeO3) sample is prepared by sol-gel method. X-ray diffraction (XRD) graph shows highly defined peaks showing that the compound possess crystalline nature. The Rietveld refined XRD data revealed that the sample has orthorhombic structure with Pbnm space group. The experimental data of structural parameters is in accordance with DFT calculated theoretical structural parameters.Fourier Transform Infrared Spectroscopy (FTIR) shows that a pure phase of YFeO3 isbeen formed. Scanning electron micrograph of YFeO3 reveals that the sample has non uniform grain structure with slight porosity in it. The grains have an average grain size of about 200 nm. Raman spectroscopic studyconfirms the structure and phase purity of the sample. The M-H curve of YFeO3shows a hysteresis loop, with a coercive field of 61 Oe and a residual magnetization of 0.516 emu/gm. Weak ferromagnetic nature of YFeO3 is attributed to the remnant magnetization value, which suggests that Fe+3 spins are slightly canted but not perfectly anti parallel. Room temperature P-E measurement of YFeO3 shows lossy ferroelectric nature of the sample.Positive Up Negative Down (PUND) measurementsdone on YFeO3 sample gives the trueswitchable polarization to be0.002 C/cm2.From the ln J versus ln E plot, the slope of the line is found to be 1.25, indicating Ohmic conduction in the sample. At 300 K, 57Fe Mössbauerspectra of YFeO3 exhibit a single magnetic sextet, confirming the presence of a single Fe site and the absence of any magnetic impurities. The value of Isomer shift is0.37 mm/s, quadrupole splitting is found to be 0.01 mm/s, Line width (Г) = 0.47 mm/s and hyper fine magnetic field (Bhf) of 49.8 T are being calculated from 57Fe Mössbauer measurements.

Fortified relaxor ferroelectricity of rare earth substituted 4-layered BaBi3.9RE0.1Ti4O15 (RE = La, Pr, Nd, and Sm) Aurivillius compounds

In this report, the effect of rare-earth (RE3+) ion substitution on structural, microstructural, and electrical properties in barium bismuth titanate (BaBi4Ti4O15) (BBTO) Aurivillius ceramics has been investigated. The Rietveld refinements on X-ray diffraction (XRD) patterns confirm that all the samples have an orthorhombic crystal system with A21am space group. Meanwhile, temperature dependent synchrotron XRD patterns reveal that the existence of dual phase in higher temperature region. The randomly oriented plate-like grains are experimentally strived to confirm the distinctive feature of bismuth layered Aurivillius ceramics. The broad band dielectric spectroscopic investigation signifies a shifting of ferroelectric phase transition (Tm) towards low temperature region with a decrease of the RE3+-ionic radii in BBTO ceramics. The origin of diffuse ferroelectric phase transitions followed by stabilization of the relaxor ferroelectric nature at high frequency region is explained using suitable standard models. The temperature dependent ac and dc conductivity results indicate the presence of double ionized oxygen vacancies in BBTO ceramics, whereas the dominance of single ionized oxygen vacancies is observed in RE-substituted BBTO ceramics. The room temperature polarization vs. electric field (P–E) hysteresis loops are shown to be well-shaped symmetric for BBTO ceramics, whereas slim asymmetric ferroelectric characteristics developed at RE-substituted BBTO ceramics.

Study of the role of dysprosium substitution in tuning structural, optical, electrical, dielectric, ferroelectric, and magnetic properties of bismuth ferrite multiferroic

Magnetoelectric multiferroics, which combine ferroelectric and magnetic characteristics, have potential use in a variety of electronic devices. In this work, Dy 3+ substituted bismuth ferrites with the chemical formula Bi 1−x Dy x FeO 3 ( x = 0.0, 0.15, 0.30, 0.45, and 0.60) were synthesized using the sol-gel auto combustion process. The effect of Dysprosium substitution in BiFeO 3 (BFO), on its structural, surface morphology, optical, electrical, dielectric, ferroelectric, and magnetic properties were studied. The rhombohedral perovskite structure of the space group ( R3c ) was confirmed via X-ray diffraction (XRD) analysis. Moreover, the crystallite size had a maximum value of 59.57 nm for x = 0.30. XRD and FTIR confirmed the substitution of Dy 3+ into BFO ferrite. Further, the structural change and absorption bands confirmed the substitution of Dy 3+ ions into the lattice. For x = 0.30, the energy bandgap of 2.81 eV was found. The resistivity and activation energy were minimum and drift mobility was maximum at x = 0.30 as compared to Dy 3+ doped BFO samples. At low frequency, the dielectric loss was reduced, while at high frequency, the dielectric loss increased with increasing frequency. The saturated polarization ( P S ), electric polarization ( E C ), and remnant polarization ( P r ) have values of 6.95 µC/cm 2 , 3.49 µC/cm 2 , and 1.53 kV/cm for x = 0.30, respectively. The maximum saturation magnetization and microwave frequencies were 10.89 emu/g and 2.41 GHz, respectively at Dy 3+ concentration x = 0.30. These materials are suitable for electronic and microwave devices. • Bi 1- x Dy x FeO 3 ( x = 0.0, 0.15, 0.30, 0.45, and 0.60) multiferoaic were successfully prepared via simple sol-gel auto-combustion. • The optical bandgap energy has values between 2.71.71 eV and 2.93 eV. • The ferroelectric nature of the samples was confirmed using the P - E loop. • Maximum magnetization saturated is observed ~ 13 emu/g. • The maximum microwave frequency has values between 1.39.39 GHz and 2.88 GHz.

Finite-size effects on ferroelectricity in rhombohedral HfO2

In this work we analyze the finite-size effects on the structural properties and on the polarization of the rhombohedral phase of HfO$_2$ subjected to a biaxial compressive strain. We show how the presence of surface charges affects the polarization, leading to a strong reduction with respect to its bulk value. This reduction can be ascribed to two mechanisms: the coupling between compressive strain and the phase-transition order parameter; the changes in the ferroelectric distortion. We give two alternative explanations of this phenomenon: from an atomistic point of view, analyzing the evolution of the bond lengths, and from a symmetry-analysis point of view, considering the changes in the amplitude of the symmetry-allowed distortions, when a slab configuration is considered. These results are independent on the slab-thickness in the considered range, suggesting the absence of a critical thickness for ferroelectricity in HfO$_2$, in agreement with the proposed improper nature of hafnia ferroelectricity.

Enhanced electrocaloric effect of P(VDF-TrFE)-based nanocomposites with Ca and Sn co-doped BaTiO3 particles

We report on the enhancemenent of electrocaloric effect in solution cast polymer nanocomposites based on Poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE) 55-45] with Ca and Sn co-substituted BaTiO3 ceramic fillers (Ba0.94Ca0.06Ti0.925Sn0.075O3, BCST). Saturated hysteresis loops and normal ferroelectric behaviour of the copolymer-based nanocomposites -as opposed to the relaxor ferroelectric nature of the terpolymer-based ones-allow the utilization of the indirect method to estimate the electrocaloric properties. Both the dielectric constant and electrocaloric temperature change (ΔT) increases as the particle content increases. Maximum adiabatic temperature change was obtained as 6.96 K under 900 kV/cm for the 10 vol % BCST containing polymer composite around the Curie temperature of the copolymer (70 °C). This relatively large electrocaloric strength is slightly lower than those obtained for terpolymer-based nanocomposites.

Multiferroic property, dielectric response and optical behavior of filled tungsten bronze Ba4Nd2Fe2-xMnxNb8O30 (0 ≤ x ≤ 1) ceramics

In this paper, the structural, magnetic, dielectric, ferroelectric and optical properties of Mn doped tungsten bronze Ba4Nd2Fe2-xMnxNb8O30 (0 ≤ x ≤ 1) ceramics were investigated in detail. All the samples are of single phase with the tetragonal structure and the group space of P4bm. Compared with antiferromagnetism in pure sample, Mn-doped samples show a weak room-temperature ferromagnetic state. The observed ferromagnetism in Mn-doped ceramics can be understood in terms of the AFM coupling of Fe-based and Mn-based sublattices via Dzyaloshinskii-Moriya interaction. The relaxor ferroelectric nature can be demonstrated in the doped samples. The sample x = 0.5 exhibits a high storage energy density U of 1.06 J/cm3 and efficiency η of 94.3%. The low-temperature dielectric relaxation obeys well with Vogel-Fulcher relation and can be ascribed to the local polarization fluctuation, while the dielectric relaxation around 300 K follows with Arrhenius law and can be attributed to the localized hopping process of electrons. In addition, the optical band gap decreases from 2.64 eV to 2.49 eV with increasing the Mn concentration.

Enantiomeric Hydrogen-bonded Chains Driving Ferroelectric and Nonlinear Optical Behavior

Organic multiferroic materials have been widely investigated due to their novel physical properties and broad applications. However, the discovery of organic small-molecular multiferroic compounds is still rare. Herein, based on the chemical design strategy of introducing homochirality, we present a pair of enantiomeric organic small-molecular compounds [HDABCO (1,4-diazabicyclo[2.2.2]octonium)][l- and d-MA (malic acid)], which displays high Curie temperatures (Tc) of 409/412 K, superior optoelectronic performance, and unique ferroelectric and ferroelastic nature. In comparison with the reported ferroelectrics with the [HDABCO]+ cation chain structure, the enantiomers show a neutral one-dimensional chain, where hydrogen bonds connect [HDABCO]+ cations and [MA]− anions. Strikingly, [HDABCO][l- and d-MA] exhibit a large second harmonic generation (SHG) intensity of about 2.46 and 2.53 times that of KH2PO4 (KDP), exceeding those of all the organic ferroelectrics (about 0.2–1 × KDP). With excellent SHG signal and ferroic properties, as well as the merit of low acoustic impedance z0 matching that of the body and easy processing, [HDABCO][l- and d-MA] are potential candidates for future biocompatible electronic devices with multi-functionality.

Behavioral remodeling of perovskite BiFeO3 by Ag-doping strategies for enhanced and ppb level acetone sensing performance: An advanced enlightenment for selectivity and sensing mechanism

Improvement of the catalytic reactions on the sensing surface or modulation of charge carriers of the sensing material are the most favorable ways to enhance sensing performance for a chemi-resistive sensor. Incorporation of noble metals can enhance the sensing features of chemi-resistive type sensors by synergistic effect of chemical (catalytic effect) or electronic (tuning of charge carrier concentration) sensitization. In this view, the present study performs a behavioral remodeling of sol-gel synthesized BiFeO3 (BFO) chemi-resistive sensor by low-cost Ag-doping strategies to enhance its acetone sensing performance with removal of irreversibility. The Ag-doped BFO (Bi0.9Ag0.1FeO3) sensor can selectively detect acetone vapor (Rcross = RAcetone/RXylene: 17; RAcetone/RHexane: 08; RAcetone/RToluene: 05; RAcetone/RMethanol: 2.5; RAcetone/REthanol: 2.2) operating at 350°C. Ag-BFO sample shows an enhancement (1.8-fold) in response (R∼22) value with 5-fold faster response time (τres∼8s) for 50 ppm acetone exposure compared to pristine BFO (R∼12, τres∼45s). Excellent repeatability over 09 loop character with high degree of long-term stability for 300 days and ppb level detection (500 ppb) favorable to biomarker recognition for critical diseases confirms the commercial viability of Ag-doped BFO sample. The ion-dipole (highest interaction energy, Ei-d = -1.02 × 10−19 J for acetone)/dipole-dipole coupling, the ferroelectric nature of BiFeO3 and sensitization effect (by metallic Ag-phase) has paved the path for revealing the selectivity and sensing mechanism for the prepared prototype in an innovative way.

Ferroelectric properties and phase transitions dynamics of Ag1−xLixNbO3 (x ≤ 0.08) ceramics

The dielectric properties of Ag 1−x Li x NbO 3 (ALNx) ceramics (x ≤ 0.08) were investigated in a broad frequency range (20 Hz – 90 THz). Nature of the room temperature phase of ALNx (x ≤ 0.04) ceramics is ferrielectric while for x ≥ 0.05 ferroelectric. The frequency dependence of dielectric permittivity is mainly caused by the relaxational mode close to the ferrielectric/ferroelectric phase transition temperature and domains dynamics at lower temperatures. At room temperature and 10 GHz frequency the dielectric permittivity is quite high (270 for ALN0), while dielectric losses tanδ low (0.037 for ALN0) for all ALN compositions, therefore these ceramics are attractive for various microwave applications. Moreover, their piezoelectric properties were also investigated and the highest piezoelectric coefficient value was observed for ALN6 (200 pC/N at room temperature and 750 pC/N at 465 K). For ALNx ceramics when x ≥ 0.06 15 polar modes were distinguished in the IR spectra and 20 polar modes for ALNx ceramics with x < 0.06, however the number or modes is temperature independent in investigated temperatures range (103–500 K). • The dielectric properties of Ag 1−x Li x NbO 3 (ALNx) ceramics (x ≤ 0.08) were investigated in a broad frequency range (20 Hz – 90 THz). • The ferroelectric nature of ALN was confirmed by the polarization versus electric field measurements. • The microwave dielectric permittivity is high, while microwave losses low for ALN ceramics, therefore ceramics are attractive for applications. • The highest piezoelectric coefficient value was observed for ALN6 ceramics (200 pC/N at room temperature and 750 pC/N at 465 K).

Effect of Crystal Structure and Phase on the Dielectric, Ferroelectric, and Piezoelectric Properties of Ca2+- and Zr4+-Substituted Barium Titanate

Barium titanate (BaTiO3) and its associate ternary metal oxide systems constitute versatile materials with immense potential for various technological applications in electronics and optoelectronics. Herein, we report on the synthesis and property optimization of lead-free ceramic samples, namely BaTiO3 (BT), BaZr0.2Ti0.8O3 (BZT), Ba0.7Ca0.3TiO3 (BCT), and BaZr0.2Ti0.8O3–0.5 Ba0.7Ca0.3TiO3 (BZT–BCT) composites. All of these materials were synthesized by the standard solid-state chemical reaction method, where tuning the composition and the crystal structure yields materials suitable for multifaceted applications related to capacitors, memory storage, and high-energy switching and transducers. Structural studies carried out using X-ray diffraction and Raman spectroscopy confirm the tetragonal phase for BT, BZT, and BZT–BCT samples, whereas BCT is a biphasic crystal system, which contains a small amount of the CaTiO3 phase. Scanning electron microscopy characterization of the surface morphology indicates the granular-dense microstructures of all of the samples. Energy dispersive spectroscopy confirms the high degree of purity and chemical homogeneity of the synthesized samples in addition to a well-maintained composition. Density measurements using Archimedes principles show that all of the samples have densities above 4.96 g/cm3. All of these materials exhibit typical polarization–electric field (P–E) hysteresis and field-induced strain butterfly (S–E) loops, which confirm their ferroelectric and piezoelectric nature. The frequency response of the dielectric constant shows a maximum dielectric constant of 2441 for pure BT and it decreases for higher frequencies, above 0.1 MHz. The dielectric properties of BT imply significant prospects for its future capacitor applications. Ferroelectric measurements, which are established by measuring the P–E hysteresis loop at 300 K, show that the BCT samples exhibit a 0.50 squareness ratio. The detailed analyses indicate that BCT is a candidate material for permanent memory storage device (FeRAM) applications, whereas BZT is good for switching applications. Furthermore, a moderately higher remnant polarization (Pr = 10.81 μC/cm2) is obtained for BT and a lower coercive field (Ec = 0.78 kV/cm) is obtained for the BZT sample. Also, piezoelectric coefficient and strain measurements show that BT has a piezoelectric coefficient of 183 ± 1 pC/N and a converse piezoelectric coefficient of 365.7 ± 2 pm/V, which are the highest values. The Q-factor for the BZT–BCT composite was observed to be 4.16 × 10–4 (cm2/μC)2, which is maximum, implying that BZT–BCT is suitable for energy conversion transducer applications. In this work, we comprehensively elucidate and discuss the properties and potential applications of BT and its associated ternary metal oxide systems.

Boosting of Magnetic, Ferroelectric, Energy Storage Efficiency, and Piezoelectric Properties of Zn Intercalated SrBi4Ti4O15-Based Ceramics.

An appropriate amount of Zn-ions are incorporated into the high Curie temperature bismuth layer-structure ferroelectric material to fabricate Sr0.2Na0.4Pr0.4Bi4Ti4O15:xwt%ZnO; (SNPBT:xZn), with x = 0, 0.10, 0.15, and 0.20 ceramic series to investigate the magnetic, ferroelectric, and energy storage efficiency and piezoelectric properties. Pure SNPBT and SNPBT:xZn ceramics have maintained their structure even after the intercalation of Zn-ions at the lattice sites of SNPBT. The addition of ZnO in SNPBT has improved the multifunctional properties of the material at x = 0.15. At room temperature, SNPBT:0.15Zn has shown a high relative density of 96%, exhibited weak ferromagnetic behavior along with a low saturation magnetization (Ms) of 0.028 emu/g with a low coercive field of 306 Oe, a high remnant polarization (Pr) of 9.04 µC/cm2, a recoverable energy density () of ~0.5 J/cm3, an energy conversion efficiency (η) of ~41%, a high piezoelectric co-efficient (d33) of 21 pC/N, and an impedance of 1.98 × 107 Ω, which are much improved as compared to pure SBT or pure SNPBT ceramics. Dielectric Constant (ɛr) versus temperature plots present the sharp peak for SNPBT:0.15Zn ceramic at a Curie temperature (TC) ~ 605 °C, confirming the strong ferroelectric nature of the ceramic. Moreover, SNPBT:0.15Zn ceramic has shown strong, piezoelectric, thermally stable behavior, which remains at 76% (16 pC/N) of its initial value even after annealing at 500 °C. The achieved results clearly indicate that SNPBT:0.15Zn ceramic is a promising candidate for future wide-temperature pulse power applications and high-temperature piezoelectric devices.

Relaxor ferroelectric nature and magnetoelectric coupling of the one dimensional frustrated Ca3CoMnO6

The typical ↑↑↓↓ spin order of the one-dimensional frustrated Ca 3 CoMnO 6 breaks the inversion symmetry and results in the ferroelectricity. But the previous calculations predict a much larger ferroelectric polarization than the experimental observation. To comprehend the divergence, Ca 3 CoMnO 6 ceramics were prepared and the magnetic, dielectric properties were studied. In accordance with the formation of short range magnetic correlation, around the antiferromagnetic transition temperature T N the Ca 3 CoMnO 6 ceramics present weak relaxor ferroelectric nature. It implies the existence of polar nanoregions. Thus, the destruction of long range ferroelectric order and the formed polar nanoregions should be responsible for the suppressed macroscopic ferroelectric polarization. The activation energy and static freezing temperature of Ca 3 CoMnO 6 are also calculated. The obtained values are E a = 6.31 × 10 −3 eV and T f = 1.5 K, respectively. Both of them are lower about two orders of magnitude than the conventional relaxor ferroelectrics. Magnetic field dependent dielectric permittivity manifests the large magnetodielectric coupling of Ca 3 CoMnO 6 . Under the application of field of 7 T, the dielectric permittivity reduces by about 10%. • Around the antiferromagnetic transition temperature T N the Ca 3 CoMnO 6 ceramics present weak relaxor ferroelectric nature. • The Ca 3 CoMnO 6 ceramicspresent weak relaxor ferroelectric nature. • Magnetic field dependent dielectric permittivity manifests the largemagnetodielectric coupling.