Enhanced low-field electrostrain in barium titanate ceramics through Ca and Hf co-doping

We systematically investigated the low-field electrostrain behavior of Ba_(1–x)Ca_xTi_(1–y)Hf_yO₃ ceramics by tuning their composition. At an applied electric field of 10 kV/cm, the materials exhibit a maximum strain (S_max) of 0.14% and an effective piezoelectric coefficient (d33∗) of 1415 pm/V, substantially exceeding the performance of conventional ferroelectric ceramics. Electrostrain responses vary significantly with dopant ratios, with the composition x = 0.1 and y = 0.1 exhibiting optimal performance. Detailed analysis reveals that this composition simultaneously delivers large reversible strain at low electric fields and retains robust polarization and electrostrain at higher fields, making it promising for microactuator and sensor applications. Microstructural characterization indicates that grain size and uniformity strongly influence electrostrain behavior. X-ray diffraction confirms that all compositions retain a perovskite structure, with dopant-dependent changes in peak width and intensity reflecting subtle variations in crystallinity. Dielectric measurements reveal high permittivity at low frequencies accompanied by low dielectric loss, suggesting potential for high-frequency and high-temperature applications. These results demonstrate that careful compositional design enables Ba_(1–x)Ca_xTi_(1–y)Hf_yO₃ ceramics to achieve exceptional low-field electrostrain performance, offering broad opportunities for devices requiring low-voltage actuation and large strain output.