Phenomenologically derived electric field-temperature phase diagrams and piezoelectric coefficients for single crystal barium titanate under fields along different axes
Aj. Bell, Phenomenologically derived electric field-temperature phase diagrams and piezoelectric coefficients for single crystal barium titanate under fields along different axes, J APPL PHYS, 89(7), 2001, pp. 3907-3914
The possible domain states of perovskite ferroelectrics under applied field
s are reviewed and, as an illustration, a phenomenological study of barium
titanate is carried out. Electric field-temperature phase diagrams, the pol
arization, and the lattice strain of barium titanate single crystals are ca
lculated from the Landau-Ginzburg-Devonshire theory of ferroelectrics for a
pplied fields up to 20 MV m(-1) and for temperatures from 1 to 450 K. The c
alculations are carried out for fields applied along the pseudocubic [001],
[101], and [111] axes, revealing the temperature and field dependence of a
ll the ferroelectric phase transitions. Large piezoelectric coefficients ca
n be identified close to field-induced transitions. Good agreement is seen
with experimental data for the piezoelectric coefficient parallel to [001]
over a wide range of temperature. The series of transitions predicted for i
ncreasing field parallel to [111] at room temperature is qualitatively simi
lar to that observed experimentally but with somewhat larger critical field
s and lower piezoelectric coefficients. Similarities are noted between the
phase diagrams for fields along [001] and [111] and those describing Pb-Ba(
2+) and Zr-Ti(4+) substitutions. (C) 2001 American Institute of Physics.