1：Experimental Design and Method Selection:

The ceramics were fabricated using a conventional solid-state reaction method. The design involved substituting LMN for BF to induce dielectric relaxation and co-doping with MnO2 and BCB to reduce conductivity and grain size.

2：Sample Selection and Data Sources:

Ceramic compositions with varying x (0-0.08), y (0, 0.1), and z (1-4) were prepared. Starting materials included Bi2O3, Fe2O3, BaCO3, TiO2, La2O3, (MgCO3)4·Mg(OH)2·5H2O, Nb2O5, MnO2, Ba(OH)2·8H2O, CuO, and H3BO3 powders from Sinopharm Chemical Reagent Co., Ltd.

3：08), y (0, 1), and z (1-4) were prepared. Starting materials included Bi2O3, Fe2O3, BaCO3, TiO2, La2O3, (MgCO3)4·Mg(OH)2·5H2O, Nb2O5, MnO2, Ba(OH)2·8H2O, CuO, and H3BO3 powders from Sinopharm Chemical Reagent Co., Ltd. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment used includes XRD (D/Max-RB, Rigaku), FE-SEM (SU8020, JEOL), LCR meter (Agilent E4980A), ferroelectric measurement system (Precision multi-ferroelectric, Radiant Technologies Inc.), dielectric testing system (Novocontrol Technologies), and voltage breakdown tester (BDJC-50kV, Beijing Beiguang Jingyi Instrument Equipment Co. Ltd). Materials are the listed powders and PVB binder.

4：Experimental Procedures and Operational Workflow:

Powders were calcined, ball-milled, pressed into discs, sintered, polished, and electrodes applied. Measurements included XRD for phase structure, Archimedes method for density, SEM for morphology, dielectric properties vs. temperature and frequency, P-E hysteresis loops, impedance spectra, and BDS tests.

5：Data Analysis Methods:

Data were analyzed using Weibull distribution for BDS, modified Curie-Weiss law for dielectric relaxation, and calculations for energy storage parameters (W, η) from P-E loops.