Synthesis and characterisation of lead magnesium niobate having exceptionally high dielectric constant

Exceptionally high dielectric constant, approximate to 28,000 (1 kHz) at T-c (-18 degrees C) has been achieved in stoichiometric lead magnesium niobate (PMN) ceramics prepared by partial oxalate route. Sintering at 1300 degrees C for 2 h in closed alumina crucible resulted in a highly dense PMN sample. Dielectric measurements with frequency showed a typical relaxer behaviour. Microstructure investigation along with electron probe microanalysis (EPMA) provide interesting clues to the observed material behaviour. Apart from grain size and density, lead oxide distribution controls the dielectric properties. (C) 1997 Elsevier Science Limited and Techna S.r.l.