Optical and magnetic properties of wollastonite and its nanocomposite crystalline structure with hematite

Abstract

It is important to develop novel, highly bioactive implants with suitable magnetic properties. Nanostructure wollastonites (calcium silicate) with various concentrations of hematite (Fe2O3) up to7% prepared by wet precipitation method and sintered up to (1273 K) were investigated. The developed phases were CaSiO3 of a monoclinic nanocrystalline structure and samples with Fe2O3 contents had both major monoclinic and minor rhombohedral nanocomposite. All samples were in the nano-size based on the XRD data, which was confirmed by HR-TEM analysis and FE-SEM micrographs. The optical diffused reflection spectra were measured at ambient atmosphere (300 K) as a function of wavelength. Optical properties exhibited semiconductor behavior with optical energy band gap of about 2.2 ± 0.07 eV, as a result of the presence of hematite, and the preparation conditions. Magnetic results showed different types of hysteresis at 300 K. Diamagnetic and paramagnetic behavior were observed for wollastonite and its nanocomposite of 1% hematite, while weak ferromagnetic behavior was elucidated for that with 3% hematite. Moreover, butterfly-shape with a bottleneck effect was predominant for nanocomposite of 5% and 7% hematite. The 7% hematite sample has higher values of magnetic parameters rather than the 5% one. The multifaceted magnetic behaviors are due to the Fe2O3 content. Coincided curves of zero field cooling (ZFC) and field cooling (FC) for the 7% hematite sample were verified in temperature range from 100 to 350 K. Advanced Fe2O3-wollastonite containing magnetic properties have triggered attention due to their possible application in bone filler and hyperthermia treatment.