CORRELATION OF MICROSTRUCTURE AND DIELECTRICAL PROPERTIES OF BaTiO3 SINTERED FROM MECHANICALLY ACTIVATED POWDERS
B.A. Marinkovic1, B.D. Stojanovic1, V.B. Pavlovic2, V.P. Pavlovic3, M.M. Ristic4
1 Center for
Multidisciplinary Studies University of Belgrade, Joint
Laboratory for Advanced Materials of SASA, Kneza Vieslava 1A,
11000 Belgrade, Yugoslavia
2 Faculty of Agriculture, Department of
Physics, University of Belgrade
3 Faculty of Engineering, University of
Belgrade
4 Serbian Academy of Sciences and Arts,
Joint Laboratory for Advanced Materials of SASA, Knez Mihailova
35, 11000 Belgrade, Yugoslavia
Mechanical activation, as one of the most outstanding processes used in the synthesis of advanced materials, is closely related to different structural changes (phase transitions, microstructural changes, generation of dislocations and crystal lattice microstrains, decrease of mean sizes of coherently diffracting domains) by the influence of mechanical energy.
Investigations of BaTiO3 obtained by firing at 800oC and sintering at 1200 oC, from a mechanically activated equimolar mixture of BaCO3 - TiO2 (rutile to anatase ratio 1.05:1) were carried out by the X-ray powder diffraction (XRPD) method. Qualitative phase analysis pointed out that the reaction in the solid state proceeded entirely and ended with the formation of a tetragonal BaTiO3 modification. Line-broadening analysis due to evaluation of different structural data (generation of dislocations, crystal lattice microstrains and mean sizes of coherently diffracting domains) was performed using the modified variance method at the (111) diffraction line, because of the specific nature of the tetragonal BaTiO3 X-ray powder diffraction pattern.
Changes of dielectric properties of BaTiO3 with the
influence of mechanical activation time were correlated with
changes at microstructural level.