A homovalent doping in PMN ceramics by using lithium and scandium
cations
MATERIALS CHEMISTRY AND PHYSICS, 112 (3):
886-891 (2008)DOI: 10.1016/j.matchemphys.2008.06.061
Abstract
The Mg2+ homovalent substitution by Li+/Sc3+ cations at the B-site
sub-lattice of the lead magnesium niobate (PMN) perovskite structure was
studied in this work. Through structural and electrical analyses, it was
observed that the dopant pair effectively substituted the Mg cation,
although an addition limit close to 2.5 mol% of dopants was observed.
Up to this concentration level, the dopant pair does not affect the
perovskite phase stability, and thus, pyrochlore free ceramics with a
T-m value of -6 degrees C and 19,000 of electric permittivity were
obtained. As a consequence of the substitution, the 1:1 chemical
ordering at the B-site was changed, leading to a less diffuse
ferroelectric-paraelectric phase transition even despite the increase of
the relaxor character. However, a 5.0 mol% addition of Li/Sc provoked
the precipitation of a small quantity of pyrochlore phase that caused a
deterioration of the ceramic electrical properties. (C) 2008 Elsevier
B.V. All rights reserved.