Superior Electrocaloric Performance Enabled by Highly Robust Monomorphic Ferrodistortion in NaNbO₃‐Based Relaxor

Abstract A synergistic realization of high electrocaloric effect (ECE) and excellent temperature stability in ferroelectrics are foundation for practical applications, which is, however, a major challenge in ferroelectric cooling community thus far. In confront with this long‐standing issue, an emergent monomorphic ferrodistortion strategy in NaNbO₃‐based relaxor is proposed with flexible tetragonal polar nanoregions immersing in short‐range oxygen octahedral tilt. This not only contributes to large quantities of polar entities to increase entropy change but also produces highly robust oxygen octahedral tilt to persist ferroelectricity and obstruct thermal agitations. Therefore, a high ΔT of 0.96 K and an ultrawide temperature span ΔT_span of 110 K with a record‐high figure of merit of 4.74 is achieved in Ta‐doped NaNbO₃‐BaTiO₃ ceramics and these superior EC performances present a remarkable breakthrough in ferroelectric bulks cooling. This work thus provides an innovative way of utilizing ferrodistortive relaxor feature with polar nanoregions immersing in oxygen octahedral tilt to simultaneously boost EC value and temperature stability and thus monomorphic ferrodistortion is proposed as an effective strategy to develop high‐performance entropy‐change materials.