Optical properties of Bi12SiO20 (BSO) and Bi12TiO20 (BTO) obtained by mechanical alloying

Mechanical alloying has been used successfully to produce nanocrystalline p owders of BTO and BSO. The milled BTO and BSO were studied by x-ray powder diffraction, DTA, infrared and Raman scattering spectroscopy. After 7 hours of milling the formation of BTO and BSO was confirmed by x-ray powder diff raction. The infrared and Raman scattering spectroscopy results suggest tha t the increase of the milling time lead to the formation of ferroelectric B TO and BSO, as seen by x-ray diffraction analysis. These materials are attr active for various electro-optical devices, including optical data processi ng. They present a number of attractive features as reversible recording ma terials for real-time holography and image processing applications. This mi lling process presents the advantage, that melting is not necessary, and th e powder obtained is nanocrystalline with extraordinary mechanical properti es. The material, can be compacted and transformed in solid piezoelectric c eramic samples. The high efficiency of the process, opens a way to produce commercial amount of nanocrystalline piezoelectric powders. Due to the nano crystalline character of this powder, their mechanical properties have chan ged and for this reason a pressure of 1 GPa is enough to shape the sample i nto any geometry. (C) 2001 Kluwer Academic Publishers.