Textured Bi₄Ti₃O₁₂ Ceramics: One‐Step Spark Plasma Sintering and Their Single‐Crystal‐Like Polar Anisotropy

Abstract

Texturing is the most effective way to engineer the performance of bismuth layer–structured ferroelectric (BLSF) ceramics by utilizing the strong anisotropy of grains, but the existing processing approaches are still complex. Herein, a one‐step spark plasma sintering (SPS) approach is demonstrated to prepare textured Bi 4 Ti 3 O 12 (BiT) ceramics with high performance. The degree of orientation can be controlled from 57% to 95% by only adjusting the sintering temperature from 840 to 1000 °C. The largest spontaneous polarization ( P s ) of ≈32.2 μC cm −2 is obtained in 95% <001> textured ceramics along the direction perpendicular to the SPS pressure, accompanied with the maximum electro‐strain of ≈0.14% and piezoelectric coefficient of 14.3 pC N −1 . Moreover, under the same conditions of poling and illumination, the textured ceramics exhibit unique anisotropic photoresponse in which the photocurrent polarity is dependent on the testing orientations. In particular, a short‐circuit photocurrent density of 8.76 nA cm −2 is achieved along the direction of SPS pressure after positive poling, while the value goes to −79.4 nA cm −2 along direction perpendicular to the SPS pressure. These results are expected to provide a paradigm to achieve highly textured BLSF ceramics for electric and photoelectric applications.