Mechanochemical fabrication of single phase PMN of perovskite structure

Single phase lead magnesium niobate, Pb(Mg1/3Nb2/3)O-3 (PMN), of high sinte red density has been successfully prepared via a novel mechanochemical fabr ication route. Nanocrystallites of perovskite PMN are triggered to form in a highly activated oxide composition consisting of PbO, MgO and Nb2O5. Unli ke in the solid state reaction of constituent oxides at high temperatures, intermediate pyrochlore phases were not observed in the activated oxide mat rix prior to the formation of perovskite PMN phase. A single phase PMN powd er of perovskite structure, which consists of more or less spherical partic les of 20-30 nm in size together with a minimized degree of particle agglom eration, was obtained when the constituent oxides were mechanically activat ed for 20 h. It was sintered to a density of similar to 99% theoretical den sity at 1050 degrees C for I h. Sintered PMN exhibits a peak dielectric con stant of 18 083 at the Curie temperature at - 11 degrees C when measured at a frequency of 100 Hz. (C) 1999 Elsevier Science B.V. All rights reserved.