1：Experimental Design and Method Selection:

The study focused on optimizing colloidal stability and rheological behavior for aqueous tape casting of KNN-based materials. Zeta potential and solubility measurements were used to determine optimal pH, and rheological analysis optimized processing parameters.

2：Sample Selection and Data Sources:

(K0.5Na0.5)0.97Li0.03Nb0.8Ta0.2O3 powder was synthesized via solid-state reaction from precursors (K2CO3, Na2CO3, Li2CO3, Nb2O5, Ta2O5), calcined, and milled to reduce particle size.

3：5Na5)97Li03Nb8Ta2O3 powder was synthesized via solid-state reaction from precursors (K2CO3, Na2CO3, Li2CO3, Nb2O5, Ta2O5), calcined, and milled to reduce particle size. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a homemade high-energy vibratory mill, Horiba LA-960 laser particle size analyzer, Zetasizer NanoZS for zeta potential, Thermo Jarrell Ash Iris Advantage ICP-OES spectrometer, IKA RW20 mechanical stirrer, Dr. Hielscher UP400S ultrasound probe, Haake MARS rheometer, tape casting setup, XRD diffractometer (Bruker D8 Advance), FEI Nova NanoSEM 230 SEM, Keysight E4980A LCR meter, HP 3325B function generator, TREK 10/40 high-voltage amplifier, homebuilt charge-to-voltage converter, and Berlincourt-type piezometer. Materials included deionized water, KCl electrolyte, Hypermer KD2 deflocculant, Duramax B1000 binder, HCl, KOH, and Mylar film.

4：Experimental Procedures and Operational Workflow:

Powder was milled for 6 hours to achieve submicron size. Suspensions were prepared at various pH levels (1-10) for zeta potential and solubility measurements. Concentrated suspensions (20-35 vol.% solids) were prepared with deflocculant and binder, sonicated, and rheologically characterized. Tape casting was performed at 30 mm/s with a 200 μm blade height, followed by drying, stacking, pressing, sintering at 1110°C, and electrical characterization.

5：Data Analysis Methods:

Data were analyzed using rheological flow curves, XRD for phase identification, SEM for microstructure, dielectric measurements at 1 kHz, hysteresis loops at 0.1 Hz, and piezoelectric coefficient measurements.