Microstructural, optical, and magnetic properties and specific absorption rate of bismuth ferrite/SiO<sub>2</sub> nanoparticles
Erna Juwita, Fitria Ayu Sulistiani, Mahardika Yoga Darmawan, Nurul Imani Istiqomah, Edi Suharyadi
Abstract
Abstract In this study, the microstructural, optical, and magnetic properties and specific absorption rate (SAR) of bismuth ferrite/SiO 2 nanoparticles were successfully investigated. The coprecipitation method was used to synthesize the nanoparticles. X-ray diffraction patterns showed the presence of sillenite-type Bi 25 FeO 40 with a body-centered cubic structure. The crystallite size of Bi 25 FeO 40 was 35.0 nm, which increased to 41.5 nm after SiO 2 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 transform infrared spectra confirmed the encapsulation of SiO 2 . Magnetic measurements at room temperature indicated weak ferromagnetic properties of the samples. The coercivity of the bismuth ferrite nanoparticles was 78 Oe, which increased after SiO 2 encapsulation. In contrast, their maximum magnetization, 0.54 emu g −1 , reduced after SiO 2 encapsulation. The determined bandgap energy of the bismuth ferrite nanoparticles was approximately 2.1 eV, which increased to 2.7 eV after SiO 2 encapsulation. The effect of SiO 2 encapsulation on the SAR of the samples was investigated using a calorimetric method. The SAR values of the bismuth ferrite nanoparticles were 49, 61, and 84 mW g −1 under alternating magnetic field (AMF) strengths of 150, 200, and 250 Oe, respectively, which decreased after SiO 2 encapsulation. The maximum magnetization and the AMF strength influenced the SAR of the nanoparticles. The results showed that SiO 2 has a significant effect in determining the microstructural, optical, and magnetic properties and SAR of the nanoparticles.