A novel and single-stage ultrasonic synthesis route has been successfully developed for the preparation of nanoparticles of pyrite (FeS2). In this study, a comparison was made on the synthesis of pyrite nanoparticles by sonication with 20 kHz apparatus and conventional method. The as-prepared pyrite was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transition electron microscopy(TEM) and Raman spectrophotometry. The XRD structure of the sample prepared by classical method indicated a typical FeS2 cubic of space group Pa3 and 16 nm size with sulfur as an impurity. Whereas the sample prepared by ultrasound showed two phases of pyrite, marcasite and cubic structures. The space groups were pa3 and 16 nm, respectively and the average size was 28.8 nm. The TEM confirmed that the pyrite in ultrasonic process was crystallized uniformly better than the classical one. The FT-IR and Raman spectra presented the Fe-S and S-S functional groups. The influences of reaction time, temperature, and acoustic power on the formation of the target compound were optimized. In ultrasonic method, the synthesis was done under milder conditions and shorter time than classical method and the product by ultrasound behaved better than classic method too.

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