1：Experimental Design and Method Selection:

The xBZT-(1-x)BCT ceramics were prepared by the conventional solid state reaction method. The starting raw materials were high purity BaCO3, Titanium (IV) oxide, CaCO3, and ZrO

2：These reagents were weighted according to the desired stoichiometric ratio, mixed and grinded using a mortar and pestle for 24 hours in pure ethanol. The grinded powder was then calcined in an alumina crucible at a temperature of 1000 0C for 2 hours in presence of air. After calcination, the powder was cooled down to room temperature naturally. The calcined powder was grinded for one hour and pelletized at a pressure of 5 tons, using KBr Press instrument. The obtained pellets were sintered at 1250 0C for 3 hrs, and then, pulverized and grinded again for 1 hr. This sintered powder was again pelletized under the previous conditions and further sintered at 1250 0C for 3 hrs. Sample Selection and Data Sources:

The x-ray diffraction (XRD) patterns of double sintered xBZT-(1-x)BCT ceramics were recorded using the Cu Kα radiation. The unpolarized Raman spectra of BZT-BCT ceramics were obtained in backscattering geometry using an Olympus microscope with a 100x objective. The

3：5 nm line of an Ar+ laser was used for excitation. The surface morphology of the ceramics was scanned using scanning electron microscope. List of Experimental Equipment and Materials:

5 High purity BaCO3, Titanium (IV) oxide, CaCO3, ZrO2, KBr Press instrument, Rigaku Mini Flex 600 XRD, Olympus microscope with a 100x objective, Ar+ laser, T64000 Jobin-Yvon spectrometer, THMS600 Linkam Stage, TESCAN VEGA 3 SBH SEM, Wayne Kerr Impedance Analyzer 6500B, P-E loop tracer (Marine India).

4：Experimental Procedures and Operational Workflow:

The XRD peaks were deconvoluted using Gaussian distribution function by Origin Software. The Raman scattering spectra were recorded at different fixed temperatures, from room temperature to 150 0C. The spectra were analyzed by fitting a sum of damped oscillators to the experimental curves. For electrical measurements, a highly conductive silver paste has been coated on the polished surface of pellets. The temperature dependence of the dielectric permittivity was measured at different frequencies ranging from 100 Hz to 1 MHz. The P-E hysteresis loops and the fatigue test on the bulk ceramics were recorded using P-E loop tracer by applying an a.c. electric field of amplitudes varying in the range of 10 kV/cm to 35 kV/cm at room temperature.

5：0C. The spectra were analyzed by fitting a sum of damped oscillators to the experimental curves. For electrical measurements, a highly conductive silver paste has been coated on the polished surface of pellets. The temperature dependence of the dielectric permittivity was measured at different frequencies ranging from 100 Hz to 1 MHz. The P-E hysteresis loops and the fatigue test on the bulk ceramics were recorded using P-E loop tracer by applying an a.c. electric field of amplitudes varying in the range of 10 kV/cm to 35 kV/cm at room temperature. Data Analysis Methods:

5. Data Analysis Methods: The XRD peaks were deconvoluted using Gaussian distribution function by Origin Software. The Raman scattering spectra were analyzed by fitting a sum of damped oscillators to the experimental curves. The temperature dependence of the dielectric permittivity was analyzed using the modified Curie–Weiss law.