In:
Science of Sintering, National Library of Serbia, Vol. 53, No. 3 ( 2021), p. 285-299
Kurzfassung:
The origin of dielectric properties of strontium titanate ceramics is
investigated using DFT calculations in periodic system. It was determined
that the main factors contributing to the increase in dielectric
permittivity are: tetragonal distortion of the normally cubic lattice, and
charge imbalance induced displacement of titanium center from its central
position. Oxygen vacancies were determined to create significantly larger
effects than other types of vacancies, like Ti and SrO. The extent of
tetragonal distortion was found to be determined by oxygen vacancy
distribution, rather than total concentration: relatively symmetrical
distribution of oxygen vacancies resulted in smaller tetragonal distortion
of the lattice, and, consequently, smaller increase in dielectric
permittivity. Charge imbalance naturally destabilizes the cubic lattice,
forcing the Ti-atom out of its central position, resulting in tetragonal
lattice with increased dielectric permittivity. The process stabilizes the
strontium titanate lattice, while increasing the c/a ratio. Therefore, the
dielectric permittivity of strontium titanate can be increased by changes to
the system that increase tetragonal distortion of the lattice and/or
introduce additional negative charge.
Materialart:
Online-Ressource
ISSN:
0350-820X
,
1820-7413
Sprache:
Englisch
Verlag:
National Library of Serbia
Publikationsdatum:
2021
ZDB Id:
2380860-3
