1：Experimental Design and Method Selection:

The LTO piezoelectric ceramics with excessive Ti content were prepared by sol-gel method combined with solid state synthesis method. The detail processes of obtaining LTO sol, gel, powders and ceramics were the same as the reference elsewhere [18]. X-ray diffraction (EMPYREAN) was used to determine the general phase structure. Software JADE and MAUD were employed to analyze explicit the samples’ phase structure, cell parameters, and atomic site occupations. Software DIAMOND was used to reveal a clear cell structure as well as the distortion angles of TiO6 oxygen octahedrons. The scanning electron microscope (SEM) (JSM-7500, Japan) was used to observe the grains’ microscopic appearance. The frequency and temperature dependences of dielectric permittivity and impedance of the ceramics were measured using an LCR meter (HP4980, Agilent, USA). Samples for piezoelectric measurements were poled under DC electric field (15kV/mm) in silicone oil at a temperature of 180 °C for 30 min. After poled for 24 hours, the piezoelectric coefficients d33 of the ceramics were measured by Belincourt meter (ZJ-3AN, Chinese Academy of Sciences, China).

2：8]. X-ray diffraction (EMPYREAN) was used to determine the general phase structure. Software JADE and MAUD were employed to analyze explicit the samples’ phase structure, cell parameters, and atomic site occupations. Software DIAMOND was used to reveal a clear cell structure as well as the distortion angles of TiO6 oxygen octahedrons. The scanning electron microscope (SEM) (JSM-7500, Japan) was used to observe the grains’ microscopic appearance. The frequency and temperature dependences of dielectric permittivity and impedance of the ceramics were measured using an LCR meter (HP4980, Agilent, USA). Samples for piezoelectric measurements were poled under DC electric field (15kV/mm) in silicone oil at a temperature of 180 °C for 30 min. After poled for 24 hours, the piezoelectric coefficients d33 of the ceramics were measured by Belincourt meter (ZJ-3AN, Chinese Academy of Sciences, China). Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Ti excess La2Ti2(1 + x)O7 (x = 0, 0.005, 0.01, 0.02, 0.05, 0.1) piezoelectric ceramics were prepared.

3：005, 01, 02, 05, 1) piezoelectric ceramics were prepared. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: X-ray diffraction (EMPYREAN), SEM (JSM-7500, Japan), LCR meter (HP4980, Agilent, USA), Belincourt meter (ZJ-3AN, Chinese Academy of Sciences, China), software JADE, MAUD, DIAMOND, Nano Measure, ZView.

4：Experimental Procedures and Operational Workflow:

Preparation of ceramics via sol-gel and solid state synthesis, XRD analysis, SEM observation, dielectric and impedance measurements, piezoelectric coefficient measurement after poling.

5：Data Analysis Methods:

Refinement analysis using MAUD for phase composition and cell parameters, impedance analysis using equivalent circuit models, grain size distribution analysis using Nano Measure and Origin.