The structural, morphological, magnetic and ferroelectric properties of calcium (Ca) doped bismuth ferrite (BFO) synthesized using a sol-gel method were studied. X-ray diffraction (XRD) analysis followed by Rietveld refinement revealed the lattice distortion of BFO after doping with 6% and 8% Ca. This also led to the reduction in particle size by creating oxygen vacancies, which was observed from the surface morphology using Field Emission Scanning Electron Microscopy (FESEM). The Magnetic properties exhibited some enhancements in saturation magnetization when the particle size was near a limiting value. The reduction in the coercive magnetic field with the increase in dopant concentration was also evident from the M-H hysteresis loop measured by Vibrating Sample Magnetometer (VSM). The Ferroelectric P-E hysteresis loop exhibited an increased symmetry in the hysteresis loop and increase in the polarization with the increase in %Ca. The 8% Ca doped BFO exhibited an incomplete saturation in the hysteresis loop and was evident to exhibit leakage current characteristics. Journal of Engineering Science 11(1), 2020, 123-131

A sustainable source of titania (TiO 2 ) is important in applications of photovoltaic devices, photocatalysts, sensors, and so forth. Beach sand from Cox's Bazar, Bangladesh, can be an excellent sustainable source of this titania as almost a quarter of it contains titania in the form of rutile and ilmenite. This study demonstrates the success of a sulfuric acid-based hydrometallurgical process in enriching titania in Cox's Bazar beach sand. The route produces precursors that can be conveniently calcined into nanocrystalline phase-pure anatase or anatase/rutile composites. We used both bulk and surface characterization to determine phase purity, crystallite size as well as surface chemistry, and morphology of the resulting anatase and rutile/anatase mixture. The proportion of anatase/rutile can be tuned by varying digestion times. This hydrometallurgical route can potentially lead to the scalable production of precursors used in producing high-performance nanocrystalline titania from a sustainable source of beach sand from Cox's Bazar of Bangladesh.

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