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Piezoelectric actuators transform electrical energy into mechanical energy, and because of their compactness, quick response time and accurate displacement, they are sought after in many applications. Polycrystalline piezoelectric ceramics are technologically more appealing than single crystals due to their simpler and less expensive processing, but have yet to display electrostrain values that exceed 1%. Here we report a material design strategy wherein the efficient switching of ferroelectric–ferroelastic domains by an electric field is exploited to achieve a high electrostrain value of 1.3% in a pseudo-ternary ferroelectric alloy system, BiFeO3–PbTiO3–LaFeO3. Detailed structural investigations reveal that this electrostrain is associated with a combination of several factors: a large spontaneous lattice strain of the piezoelectric phase, domain miniaturization, a low-symmetry ferroelectric phase and a very large reverse switching of the non-180° domains. This insight for the design of a new class of polycrystalline piezoceramics with high electrostrains may be useful to develop alternatives to costly single-crystal actuators.

In this paper, we have investigated the effect of Cr3+ substitution on the crystal structure, microstructure, dielectric and magnetic behavior of the morphotropic phase boundary (MPB) composition of the multiferroic ceramic 0.675BiFe(1−x)CrxO3–0.325PbTiO3 (x = 0, 0.02 and 0.05). The average grain size of the specimens increased from ~ 150 nm for x = 0 to 470 nm for x = 0.05. Rietveld refinement analysis of the X-Ray powder diffraction patterns confirmed the coexistence of multiphase i.e. monoclinic Cc and tetragonal P4 mm polymorphs for all the compositions. The system exhibits weak ferromagnetism for x = 0.05. We estimated the magnetoelectric interaction constant (γ ~ 0.31) for x = 0.05 by Ginzburg–Landau theory. The value of magnetoelectric coupling coefficient (\\[_ME\\]) is found to be 0.054 mV/cm-Oe, 0.073 mV/cm-Oe, 0.133 mV/cm-Oe for x = 0, 00.02 and 0.05, respectively. High temperature dielectric data also reveals that Curie temperature decreases with increasing Cr3+ concentration.

Hybrid multiferroic materials exhibiting morphotropic phase boundary (MPB) with enhanced ferroelectric and ferromagnetic properties has shown great potential for future technologies. In this paper, we report structural, ferroelectric, piezoelectric, magnetic and magnetoelectric characteristics of 0.7BiFeO3-0.3Pb0.5Ba0.5TiO3 (BFPTBT-Pure) and 0.7BiFeO3-0.3Pb0.5Ba0.5TiO3 + Mn0.5% (BFPTBT-Mn5%) ceramic compositions synthesized via conventional solid state reaction route. The crystallinity of the compositions exhibits polymorphs of rhombohedral (R3c) and tetragonal (P4mm) symmetries forming morphotropic phase boundary (MPB). Highly dense SEM micrographs were observed with an average grain size 0.57 m and 0.62 m for BFPTBT-Pure and BFPTBT-Mn5%, respectively. Mn doped ceramic sample. Improved ferroelectric behavior has been observed with Mn doping in the composition as the value of remnant polarization increases from 2.46 C cm−2 to 7.63 C cm−2 recorded at an applied frequency of 50 Hz. The piezoelectric coefficients for BFPTBT-Pure and BFPTBT-Mn5% were found to be 36pC/N and 57pC/N respectively. M-H hysteresis loops depicted that remnant magnetization increases with Mn addition in the sample. The Curie transition temperature (Tc) was observed to be 447 °C and 467 °C for BFPTBT-Pure and BFPTBT-Mn5% ceramics, respectively. The magnetoelectric coupling was confirmed through the observation of magnetic field induced relative change in dielectric constant (Magnetocapacitance: MC). MC was found to be 9.49% and 11.81% for BFPTBT-Pure and BFPTBT-Mn5%, respectively.

(0.9 − x)BiFeO3–xPbTiO 3 –0.1BaTiO 3 for 0.20 ≤ x ≤ 0.24 ceramic sample was prepared by conventional solid state reaction method. X-ray diffraction analysis confirmed the existence of morphotropic phase boundary (MPB) between monoclinic (Cc) and tetragonal (P4mm) phases. Dielectric measurements revealed the diffusive and dispersive relaxor-like behavior for all the composition in the vicinity of MPB. A broad dielectric maximum was observed in temperature dependent real part of dielectric permittivity for all the compositions. The relaxor-like character was quantified by using Vogel–Fulcher relationship, which yielded activation energy of 0.190–0.225 eV, characteristic frequency of the order of 10 12  Hz and freezing temperature ranging 189.0–200.5 °C. The low remnant polarization and high coercive field suggests that the polarization in nanodomains is weakly coupled, which limits the long range ordering of dipoles and alters the system from normal ferroelectric to relaxor ferroelectric. The high value of tetragonal strain (c/a ~ 1.16) results in a weak piezoelectric response for all the ceramic compositions.

The increasing demand for wearable electronics, point-of-care diagnostics, and integrated microsystems necessitates thin-film and microbatteries that combine high energy density, fast kinetics, and intrinsic safety. In this work, we develop Zn-based thin-film batteries (Zn-TFBs) and microbatteries (Zn-MBs) using K -pre-intercalated V O ·nH O cathodes and reveal a fundamentally distinct charge-storage mechanism. Contrary to the conventional paradigm where metal-ion pre-intercalation merely enlarges interlayer spacing, K incorporation induces interlayer contraction accompanied by substantial oxygen-vacancy generation and mixed-valence (V /V ) formation. These coupled lattice and electronic modulations activate proton-dominated transport pathways, enabling cooperative H /Zn co-storage and markedly accelerated reaction kinetics. Density functional theory calculations further confirm that the enhanced electrochemical behavior cannot be explained by interlayer expansion alone, but originates from defect-mediated proton conduction and vacancy-stabilized redox centers. Benefiting from this defect-engineered proton-Zn synergistic storage, the K -modified V O ·nH O cathode delivers an areal capacity of 200.9 µAh cm and an areal energy of 150 µWh cm at 50 µA cm in Zn-TFBs, together with a high areal capacity of 49 µAh cm in Zn-MBs. This study establishes K -triggered defect and valence-state engineering as a powerful strategy to regulate proton-coupled charge storage in hydrated vanadium oxides, opening a viable pathway toward high-energy Zn-based energy-storage systems.

Hybrid multiferroic materials exhibiting morphotropic phase boundary (MPB) with enhanced ferroelectric and ferromagnetic properties has shown great potential for future technologies. In this paper, we report structural, ferroelectric, piezoelectric, magnetic and magnetoelectric characteristics of 0.7BiFeO 3 –0.3Pb 0.5 Ba 0.5 TiO 3 (BFPTBT-Pure) and 0.7BiFeO 3 –0.3Pb 0.5 Ba 0.5 TiO 3  + Mn0.5% (BFPTBT-Mn5%) ceramic compositions synthesized via conventional solid state reaction route. The crystallinity of the compositions exhibits polymorphs of rhombohedral ( R3c ) and tetragonal ( P4mm ) symmetries forming morphotropic phase boundary (MPB). Highly dense SEM micrographs were observed with an average grain size 0.57 μ m and 0.62 μ m for BFPTBT-Pure and BFPTBT-Mn5%, respectively. Mn doped ceramic sample. Improved ferroelectric behavior has been observed with Mn doping in the composition as the value of remnant polarization increases from 2.46 μ C cm −2 to 7.63 μ C cm −2 recorded at an applied frequency of 50 Hz. The piezoelectric coefficients for BFPTBT-Pure and BFPTBT-Mn5% were found to be 36pC/N and 57pC/N respectively. M-H hysteresis loops depicted that remnant magnetization increases with Mn addition in the sample. The Curie transition temperature ( T c ) was observed to be 447 °C and 467 °C for BFPTBT-Pure and BFPTBT-Mn5% ceramics, respectively. The magnetoelectric coupling was confirmed through the observation of magnetic field induced relative change in dielectric constant (Magnetocapacitance: MC ). MC was found to be 9.49% and 11.81% for BFPTBT-Pure and BFPTBT-Mn5%, respectively.

The increasing demand for wearable electronics, point-of-care diagnostics, and integrated microsystems necessitates thin-film and microbatteries that combine high energy density, fast kinetics, and intrinsic safety. In this work, we develop Zn-based thin-film batteries (Zn-TFBs) and microbatteries (Zn-MBs) using K+-pre-intercalated V2O5·nH2O cathodes and reveal a fundamentally distinct charge-storage mechanism. Contrary to the conventional paradigm where metal-ion pre-intercalation merely enlarges interlayer spacing, K+ incorporation induces interlayer contraction accompanied by substantial oxygen-vacancy generation and mixed-valence (V4 +/V5 +) formation. These coupled lattice and electronic modulations activate proton-dominated transport pathways, enabling cooperative H+/Zn2 + co-storage and markedly accelerated reaction kinetics. Density functional theory calculations further confirm that the enhanced electrochemical behavior cannot be explained by interlayer expansion alone, but originates from defect-mediated proton conduction and vacancy-stabilized redox centers. Benefiting from this defect-engineered proton-Zn2 + synergistic storage, the K+-modified V2O5·nH2O cathode delivers an areal capacity of 200.9 µAh cm- 2 and an areal energy of 150 µWh cm- 2 at 50 µA cm- 2 in Zn-TFBs, together with a high areal capacity of 49 µAh cm- 2 in Zn-MBs. This study establishes K+-triggered defect and valence-state engineering as a powerful strategy to regulate proton-coupled charge storage in hydrated vanadium oxides, opening a viable pathway toward high-energy Zn-based energy-storage systems.The increasing demand for wearable electronics, point-of-care diagnostics, and integrated microsystems necessitates thin-film and microbatteries that combine high energy density, fast kinetics, and intrinsic safety. In this work, we develop Zn-based thin-film batteries (Zn-TFBs) and microbatteries (Zn-MBs) using K+-pre-intercalated V2O5·nH2O cathodes and reveal a fundamentally distinct charge-storage mechanism. Contrary to the conventional paradigm where metal-ion pre-intercalation merely enlarges interlayer spacing, K+ incorporation induces interlayer contraction accompanied by substantial oxygen-vacancy generation and mixed-valence (V4 +/V5 +) formation. These coupled lattice and electronic modulations activate proton-dominated transport pathways, enabling cooperative H+/Zn2 + co-storage and markedly accelerated reaction kinetics. Density functional theory calculations further confirm that the enhanced electrochemical behavior cannot be explained by interlayer expansion alone, but originates from defect-mediated proton conduction and vacancy-stabilized redox centers. Benefiting from this defect-engineered proton-Zn2 + synergistic storage, the K+-modified V2O5·nH2O cathode delivers an areal capacity of 200.9 µAh cm- 2 and an areal energy of 150 µWh cm- 2 at 50 µA cm- 2 in Zn-TFBs, together with a high areal capacity of 49 µAh cm- 2 in Zn-MBs. This study establishes K+-triggered defect and valence-state engineering as a powerful strategy to regulate proton-coupled charge storage in hydrated vanadium oxides, opening a viable pathway toward high-energy Zn-based energy-storage systems.

In this paper, we have reported the effect of rare earth Nd 3+ ion substitution on crystal structure, ferroelectric, electrical and magnetic behavior of morphotropic phase boundary (MPB) composition of polycrystalline ceramics 0.7Bi (1−x) Nd x FeO 3 –0.3PbTiO 3 (BNFPT), where x = 0, 0.05, 0.10. Rietveld refinement of XRD profiles confirms coexistence of rhombohedral R3c and tetragonal P4mm polymorphs forming MPB for all the compositions. We observed that the remnant polarization P r increases with increasing Nd 3+ concentration. Piezoelectric studies show gradual increase in piezoelectric coefficient (d 33 ) from 11 to 34 pC/N with increase in Nd 3+ concentration for BNFPT samples. All compositions exhibit weak ferromagnetic character. For the same composition range, the study of dielectric behavior revealed gradual decrease in Curie temperature (T c ) as we increased doping content of Nd 3+ .

Over the years attempts have been made to compensate for the inherent weaknesses in the bulk state of the multiferroic BiFeO3, such as high leakage current and the absence of ferromagnetic correlation, and exploit its magnetoelectric potential by forming solid solutions with other perovskites. Studies in the recent few years have shown that alloying of BiFeO3 with BaTiO3, both with and without additives, can induce both ferroelectric and ferromagnetic switching. While the coexistence of both the ferroic orders is encouraging from the view point of technological applications, the origin of ferromagnetism in this system remains elusive. Here, we synthesized such compositions and carried out a detailed structural analysis employing magnetic separation of the powder particles. We found that the origin of ferromagnetism lies in the spontaneous precipitation of a minor ( ~ 1 wt %) barium hexaferrite (BaFe9O19) phase, often undetected in routine x-ray diffraction studies of powders sampled from the entire specimen. We also demonstrate that inspite of the insignificant fraction the ferrimagnetic phase, this self-grown composite exhibit noticeably enhanced ferroelectric switching in the presence of external magnetic field. We obtained a dc magnetoelectric coupling of ~ 9 x 10-8 s/m, a value which is comparable to what has been reported for layered ferroelectric/ferromagnetic laminates and bilayer thin film ferroelectric-ferromagnetic hetrostructures. Our study suggests that reasonably large magnetoelectric coupling is realizable in simple 0-3 ferroelectric-ferromagnetic bulk composites provided synthesis strategies are developed which induces spontaneous precipitation of the ferromagnetic phase in small volume fraction to ensure good insulating behaviour of the composite thus developed.