BiFeO3 (BFO), a room temperature multiferroic, undergoes a series of structural transformations under varying strain conditions by utilizing appropriate substrates for a specific strain condition. In this study, epitaxial thin films of BFO were grown on La0.7Sr0.3MnO3±δ (LSMO), a strain tuning layer on LaAlO3[LAO (001)] substrates, using pulsed laser ablation. LSMO layers of varying thicknesses from 2 nm to 20 nm were grown followed by a BFO layer of a fixed thickness (20 nm). A strained layer of ∼2 nm thick LSMO stabilizes the tetragonal like phase of BFO. Increasing the thickness of the LSMO layer to 10 nm results in a mixed phase with rhombohedral (R) and tetragonal (T) domains, and a further increment of the LSMO layer thickness to 20 nm stabilizes the rhombohedral phase of BFO. The tetragonal phase with weak monoclinic distortion possessed 180° domains with dominant out-of-plane polarization components. However, the mixed phase (R + T) possessed various plausible polarization components in both out-of-plane and in-plane directions. Further, a thermodynamically consistent model based on the phase field approach was implemented to investigate the role of strain on the formation of domain patterns with various polarization components and piezoelectric coefficients. The simulated domain structure exhibited a similar transformation on the dominant polarization components as observed in experiments across different phases of BFO. Our simulations show that the elastic constraint along the z-direction enhances the tetragonality of BFO. The piezoelectric (d33) coefficient was found to be ∼46 pm/V for the 20 nm mixed phase BFO, which was nearly a 200% increment compared to the single phase BFO thin films on LAO.

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Environment-friendly lead-free pyroelectrics are indispensable for pyroelectric generators to extract energy from low-gradient waste heat to power portable electronic devices. The pyroelectric response near room temperature is essential for high performance energy harvesters, which is unfortunately limited to lead-free ferroelectrics. Herein, BaTiO3-based ferroelectric–ZnO semiconductor composites were reported to exhibit superior pyroelectric energy harvesting characteristics near room temperature. The role of ZnO on the improved ferroelectric characteristics is elucidated through impedance and Rayleigh analysis. Notably, more than 100% enhancement in pyroelectric coefficient (7250 μC/(m2 K)) is displayed by the composite at 45 °C, making it a suitable candidate for pyroelectric energy harvesting applications. The composite showed the figure of merit of pyroelectric energy harvesting F E = 3.032 kJ/(m3 K2), which is the highest value near room temperature among the reported results.

The intrinsic distortions present in rare-earth orthochromites (RCrO 3) observed from lanthanum to lutetium (in R-site) can influence the magnetic properties like Neel transition and weak ferromagnetic coupling. A nonmagnetic cation with similar ionic radius would be a suitable candidate to engineer the inherent distortions of particular orthochromite. In this study, bismuth (Bi 3+) with a 6s 2 lone pair was chosen to substitute in neodymium (Nd 3+) site of NdCrO 3 (NCO) to tailor the intrinsic structural distortions. The variation of optical absorption edge evidently suggests that Bi (6s 2) substituted in the magnetic rare-earth Nd 3+ influences the Cr-O overlap integral. The interaction of Bi cation with oxygen bonds influences the structural distortions through Cr-O polyhedral, which are evident from Raman scattering studies. The observed structural and magnetic properties of similar ionic radius of Bi 3+ in Nd 3+ reveal that intrinsic structural distortions are interrelated to enhanced weak ferromagnetic component and change in Neel and spin reorientation temperatures in our compounds. In addition, a reduction in the optical bandgap of NCO from 3.1 to 2.6 eV was observed.