Editors : M. Dawber
a1 [email protected], Carnegie Institution of Washington, Geophysical Laboratory, Washington, District of Columbia, United States
a2 [email protected], United States
Recent first principles simulations using density functional theory and novel low temperature x-ray diffraction experiments show the existence of a high pressure morphtotropic phase boundary (MPB) in pure PbTiO3. In this paper we apply chemical pressure by substituting smaller atoms in the ABO3 ‘A’ and ‘B’ sites. We find that the ground state of layered PbSnTiO3 (PSnT) is Pmm2, and for rocksalt SnGeTiO3 and PbGeTiO3 is R3m. The polarization of PbSnTiO3 is large (1.13,0,0)C/m2 and is due to the large Born effective charge of the small ‘Sn’ atom. We estimate the d33 for PSnT to be about 2400 pC/N, which is as large as that of currently used relaxor ferroelectrics.
(Received November 24 2008)
(Accepted February 03 2009)