| Summary: | In this study, the microstructural, optical, and magnetic properties and specific absorption rate (SAR)
of bismuth ferrite/SiO2 nanoparticles were successfully investigated. The coprecipitation method was
used to synthesize the nanoparticles. X-ray diffraction patterns showed the presence of sillenite-type
Bi25FeO40 with a body-centered cubic structure. The crystallite size of Bi25FeO40 was 35.0 nm, which
increased to 41.5nmafter SiO2 encapsulation. Transmission electron microscopy images confirmed
that all samples were polycrystalline. The presence of Si–O–Si (siloxane) stretching at 1089 cm−1 in
Fourier transforminfrared spectra confirmed the encapsulation of SiO2.Magneticmeasurements at
roomtemperature indicated weak ferromagnetic properties of the samples. The coercivity of the
bismuth ferrite nanoparticleswas 78Oe,which increased after SiO2 encapsulation. In contrast, their
maximummagnetization, 0.54 emu g−1, reduced after SiO2 encapsulation.The determined bandgap
energy of the bismuth ferrite nanoparticles was approximately 2.1 eV,which increased to 2.7 eVafter
SiO2 encapsulation. The effect of SiO2 encapsulation on the SARof the sampleswas investigated using a
calorimetricmethod. The SARvalues of the bismuth ferrite nanoparticleswere 49, 61, and 84mWg−1
under alternatingmagnetic field (AMF) strengths of 150, 200, and 250Oe, respectively,which decreased
after SiO2 encapsulation.Themaximummagnetization and theAMF strength influenced the SARof the
nanoparticles. The results showed that SiO2 has a significant effect in determining the microstructural,
optical, andmagnetic properties and SARof the nanoparticles.
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