Energy storage, electrocaloric and optical property studies in Ho-modified NBT – BT lead-free ferroelectric ceramics

(1-x)(Na₀.₅Bi₀.₅)TiO₃-xCaTiO₃ ceramics: Investigating structural and microstructural features for enhanced dielectric properties

“…Among all compositions, the maximum grain size and ρ r are observed in NBT-0.15CT. The coexistence of a non-polar phase ( Pnma ) alongside polar phases ( R 3 c ) within the solid solution effectively lowers the energy barrier, facilitating enhanced polarization switching through an extended polarization mechanism [ 43 ]. This unique structural arrangement, coupled with the nanometric grain size, significantly boosts the material's performance, making it a standout candidate for efficient energy storage [ 44 , 45 ].…”

Large electrocaloric effect and wide working area in the transition from ferroelectric to nanodomains

“…In order to obtain a larger ∆T, a larger polarization variation is required. 16 Furthermore, A larger T span , defined as the region where ∆T exceeds 90% of ∆T max , is also necessary to evaluate the practical applicability of the electrocaloric material.…”

“…E 2 and E 1 are two different electric field strengths, and P is the peak polarization ( P max ) at different electric field strengths. In order to obtain a larger ∆ T , a larger polarization variation is required 16 . Furthermore, A larger T span , defined as the region where ∆ T exceeds 90% of ∆ T max , is also necessary to evaluate the practical applicability of the electrocaloric material.…”

Energy‐storage properties of (0.7Bi0.65Na0.35Fe0.3Ti0.7O3–0.3Sr0.85Bi0.1TiO3)–NaTaO3 relaxor under low electric fields

“…There are two states in relaxor materials: the ergodic relaxation state and the non‐ergodic relaxation state 4 . In the non‐ergodic relaxation state, polar nanoregions can nucleate and grow into a macroscopic ferroelectric domain under the action of the electric field, accompanied by an irreversible non‐ergodic relaxation‐ergodic relaxation phase transition, which leads to strong ferroelectricity after the removal of the applied electric field, resulting in high P r 5,6 . In the ergodic relaxation state, materials undergo a reversible phase transition under the action of the electric field, exhibiting a high polarization, and return to the ergodic relaxation state when the applied electric field is removed, showing a low P r value 4,7 .…”

“…4 In the non-ergodic relaxation state, polar nanoregions can nucleate and grow into a macroscopic ferroelectric domain under the action of the electric field, accompanied by an irreversible non-ergodic relaxation-ergodic relaxation phase transition, which leads to strong ferroelectricity after the removal of the applied electric field, resulting in high P r . 5,6 In the ergodic relaxation state, materials undergo a reversible phase transition under the action of the electric field, exhibiting a high polarization, and return to the ergodic relaxation state when the applied electric field is removed, showing a low P r value. 4,7 Undoped Na 1/2 Bi 1/2 TiO 3 (NBT) is in a non-ergodic relaxation state at room temperature, 8 and it has large structural distortion and large polarization response due to the lone pair electrons on the 6 s of Bi 3+ .…”