Enhanced pyroelectric properties of Bi4Ti3O12 ceramics synthesized via solid-state route for sensing applications
摘要
In the present work, a member of the Aurivillius family, Bi4Ti3O12 (BTO), was synthesized and comprehensively characterized for its structural, morphological, dielectric, ferroelectric, and pyroelectric properties. XRD analysis confirmed the formation of a single-phase Aurivillius-type bismuth layered- perovskite structure with an orthorhombic crystal system (space group B2cb) with refined lattice parameters a ≈ 5.45 Å, b ≈ 5.41 Å, and c ≈ 32.83 Å. Rietveld refinement showed high structural integrity, while the analysis of TiO6 octahedra evidenced the local distortion responsible for spontaneous polarization. Scanning electron microscopy (SEM) images showed uniformly distributed grains (~ 2.6 µm); energy dispersive X-ray (EDX) with elemental mapping further confirmed compositional homogeneity. XPS spectra confirmed the oxidation states of Bi3+ and Ti4+, further validating phase purity and intense chemical ordering. Dielectric measurements in a broad temperature range from 200 °C to 700 °C displayed a sharp anomaly at ~ 650 °C corresponding to the Curie temperature, representing a transition from the ferroelectric to the paraelectric phase. Ferroelectric P–E hysteresis loops showed a remnant polarization of up to 52 µC/cm2 and a clear domain switching at fields up to 230 kV/cm. Importantly, the pyroelectric coefficient showed an enhancement in the range from 1.42 × 10–4 to 16.28 × 10–4 C m⁻2 K⁻1 accompanying the leakage current reduction. The calculated figures of merit (Fi = 15.54 × 10–10 mV−1, Fv = 11.53 × 10–2 m2•C−1, Fd = 39.83 µPa−1/2) evidence the promising potential of the material in lead-free pyroelectric devices. The sensor based on Bi4Ti3O12, under identical measuring conditions, provided a respectable output of ≈1.8 V, thus ranking this material as one of the best candidates in eco-friendly pyroelectric and energy-harvesting applications.