**2. Experimental**

### **2.1 Synthesis of the composite samples**

The ceramic composites (0.5Bi5Ti3FeO15-0.2La0.67Sr0.33MnO3-0.3Bi2Fe4O9) were prepared by the sol–gel modified method. At first, BTFO, LSMO, and BFO samples were synthesized separately via a sol–gel auto combustion process. The chemical reagent used for the preparation of the BTFO sample were bismuth nitrate (Bi(NO3)3.5H2O), iron nitrate (Fe(NO3)3.9H2O), and titanium isopropoxide (TiC12H28O4). The above chemicals were taken from Sigma-Aldrich with greater than 99.9% purity form. The deionized water was used to mix the nitrates. Bismuth nitrate and titanium isopropoxide were immiscible with the deionized water. The required drop of nitric acid was used to dissolve the chemicals and get the transparent white-colored solution. After that, add the iron nitrate to the above solution and heat it on the hot plate at 100°C. Then the desired ratio of ethylene glycol and citric acid (1:1.5) was added to the mixture. All the reagents are mixed completely and lead to the formation of the gel. The xerogel was dried on the hot plate overnight and crushed to form the homogenous powder. The resultant powder was pre-sintered in a tubular furnace at 600°C for 2 h. A similar method was used for the preparation of LSMO and BFO samples. Only the difference in the precursor materials and pre-sintered temperatures. The starting materials such as lanthanum nitrate (La(NO3)3.6H2O), manganese nitrate (Mn(NO3)2.4H2O), strontium nitrate (Sr(NO3)2) and bismuth nitrate, iron nitrate were used for the preparation of LSMO and BFO sample, respectively. The obtained xerogel powder was pre-sintered at 800°C for 4 h and 800°C for 2 h for the LSMO and BFO samples, respectively.

Finally, the composite (0.5Bi5Ti3FeO15-0.2La0.67Sr0.33MnO3-0.3Bi2Fe4O9) was prepared by taking the desired ratio of as-synthesized BTFO, LSMO, and BFO powder. The proper weight percentage of 50% BTFO:20% LSMO:30% BFO (abbreviated as BLB523) was taken and mixed thoroughly with the help of agate mortar and pestle to get the homogeneous powder. The obtained powder was pressed to form the pellet and finally sintered at 900°C for 4 h.
