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DF: Dielektrische Festkörper

DF 7: Dielectric and Ferroelectric Thin Films and Nanostructures II

DF 7.5: Vortrag

Mittwoch, 29. März 2006, 15:50–16:10, K{\"O}N Farb

DFT investigation of PZT bulk and surface properties — •Igor Chaplygin, Sibylle Gemming, and Gotthard Seifert — Physikalische Chemie und Elektrochemie, TU Dresden, D-01062 Dresden.

Density-functional investigations on the structural, electronic and elastic properties of lead zirconate titanate (PZT) were carried out, employing both an all-electron and a pseudopotential technique. The lead/zirconium distribution was studied with a supercell approach and with the random mixing provided by the CPA and the alchemical mixing scheme. All approaches yield a nearly linear dependence of the structural and eleastic properties of the Zr:Ti ratio. Only the character of the conduction band changes from Pb-based 6p states to Ti-3d states if the Ti content exceeds 50 Thus, the (001) surfaces of PZT were investigated with the alchemical mixing technique. All surfaces exhibit an inward relaxation of the termination plane and a less pronounced outward relaxation of the next lower plane. The strongest relaxations of up to 20 constant occur at the less densely packed PbO termination. Similarly, the relaxations of the Zr-rich systems are larger than the ones in the Ti-rich models. Thus, the slab thickness required to obtain stable bulk-type PZT in the centre of the slab varies between 1.6 to 2.4 nm.