Surface Modification of Sol–Gel Synthesized Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ using Stearic Acid Additives

Barium calcium zirconium titanium oxide (BCZT) is a lead‐free piezoelectric ceramic material with exceptional electromechanical properties, making it highly valuable in applications such as sensors, actuators, and transducers. Among various synthesis methods for BCZT, the sol–gel (SG) route is chosen here because it allows precise control of the composition and a lower processing temperature compared to solid‐state sintering. However, achieving high electromechanical response through the SG synthesis route remains challenging. In this study, the response is increased up to 359 pC N⁻¹ by coating the powder surface with a 0.69 nm stearic acid (SA) layer. The SG derived Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT50) is uniaxially pressed and then subjected to cold isostatic pressing to evaluate its properties without the influence of advanced shaping techniques. After heat treatment and corona polarization, the piezoelectric coefficient d₃₃ is determined to be 21–46 pC N⁻¹. The SA coating enhances powder flowability and compressibility during pressing, due to chemical interactions at the particle surfaces. To better understand the nature of the SA‐BCZT interaction and the formation of surface stearates, attenuated total reflectance‐Fourier transform infrared spectroscopy, X‐ray diffraction, and Raman spectroscopy are employed. These analyses help clarify the influence of the coating on the powder characteristics and its contribution to improved electromechanical performance.