Abstract
We have examined the local structure of PbMg1/3Nb 2/3O3-PbTiO3 (PMN-PT) and PbZn 1/3Nb2/3O3-PbTiO3 (PZN-PT) solid solutions using density functional theory. We find that the directions and magnitudes of cation displacement can be explained by an interplay of cation-oxygen bonding, electrostatic dipole-dipole interactions, and short-range direct and through oxygen Pb-B-cation repulsive interactions. We find that the Zn ions move off center in the PZN-PT system, which also enables larger Pb and Nb/Ti displacements. The off-centering behavior of Zn lessens Pb-B-cation repulsion, leading to relaxor-to-ferroelectric and rhombohedral-to-tetragonal phase transitions at low PbTiO3 content in the PZN-PT system. We also show that a simple quadratic relationship exists between Pb and B-cation displacements and the temperature maximum of the dielectric constant, thus linking the enhanced displacements in PZN-PT systems with the higher transition temperatures.
| Original language | English |
|---|---|
| Article number | 220101 |
| Pages (from-to) | 220101-1-220101-4 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 70 |
| Issue number | 22 |
| DOIs | |
| State | Published - Dec 2004 |
| Externally published | Yes |
Bibliographical note
Funding Information:This work was supported by the Office of Naval Research, under Grant No. N-000014-00-1-0372 and through the Center for Piezoelectrics by Design. We also acknowledge the support of the National Science Foundation, through the MRSEC program, Grant No. DMR00-79909. A.M.R. acknowledges the support of the Camille and Henry Dreyfus Foundation. Computational support was provided by the Center for Piezoelectrics by Design, the DOD HPCMO, and DURIP. We would also like to thank Peter K. Davies for stimulating discussions.