MECHANICALLY ACTIVATED SYNTHESIS OF NANOCRYSTALLINE POWDERS OF FERROELECTRIC BISMUTH VANADATE

摘要

Mechanical milling of a stoichiometric mixture of Bi2O3 and V2O5 yielded nanosized powders of bismuth vanadate, Bi2VO5.5 (BiV). Structural evolution of the desired BiV phase, through an intermediate product (BiVO4), was monitored by subjecting the powders, ball milled for various durations to powder XRD, DTA, and TEM studies. XRD studies indicate that the relative amount of the BiV phase present in the ball-milled mixture increases with increase in milling time and its formation reaches completion within 54 h of milling. As-synthesized powders were found to stabilize in the high-temperature tetragonal (gamma) phase. DTA analyses of the powders milled for various durations suggest that the BiV phase-formation temperature decreases with increase in milling time. The nanometric size (30 nm) of the crystallites in the final product was confirmed by TEM and XRD studies. TEM studies clearly demonstrate the growth of BiV on Bi2O3 crystallites. 26 refs.