1：Experimental Design and Method Selection:

The synthesis was performed using a solid-state reaction technique to prepare LaFeO3 and La

2：9(Sm/Nd)1FeO3 nanopowders. This method was chosen for its advantages in producing compounds with controlled properties. Sample Selection and Data Sources:

Stoichiometric amounts of metal oxides (La2O3, Fe2O3, Sm2O3, Nd2O3) were used as starting materials, purchased from Sigma-Aldrich at

3：9% purity. List of Experimental Equipment and Materials:

Equipment included an agate mortar for grinding, calcination and sintering furnaces, Bruker D2 PHASER x-ray diffractometer, BRUKER ALPHA FT-IR spectrophotometer, Horiba Jobin–Yvon HR 800 UV spectrometer for Raman spectroscopy, JEOL ZEM scanning electron microscope with EDS, PerkinElmer spectrophotometer for UV-Vis, Radiant Technologies P–E loop tracer, and Lakeshore vibrating sample magnetometer (VSM model 7407). Materials were the metal oxides.

4：7). Materials were the metal oxides. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The powders were mixed, ground with acetone, calcined at 900°C for 12 h, ground again, sintered at 1000°C and then 1200°C for 16 h with intermediate grinding. Characterizations included XRD, FT-IR, Raman, SEM-EDS, UV-Vis, P-E hysteresis, and M-H curves.

5：Data Analysis Methods:

XRD data were analyzed using Rietveld refinement with GSAS program, crystallite size calculated using Scherrer's formula, optical band gap determined from Tauc plots, and magnetic parameters extracted from hysteresis loops.