Regensburg 2004 – scientific programme

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DF: Dielektrische Festkörper

DF 1: Elektrische und optische Eigenschaften I

DF 1.3: Talk

Monday, March 8, 2004, 10:30–10:50, H11

Electrical and optical properties of PbTiO₃ single crystals at room temperature — •Hassan Chaib, Frank Schlaphof, Tobias Otto, and Lukas Eng — Institute of Applied Photophysics, University of Technology Dresden,D-01062 Dresden, Germany

We present a theoretical approach for studying the electrical and optical properties of lead titanate (PbTiO₃). The microscopic model bases on the orbital approximation in correlation with the dipole-dipole approximation and accounts for the electronic polarizability anisotropy of all constituent ions, their ionic shifts, as well as the crystalline deformations. The model was previously tested for other ferroelectric oxide materials when calculating the properties of mono-domain tetragonal BaTiO₃, KNbO₃, and rhombohedral LiNbO₃, i.e. the ferroelectricity and optical birefringence, as well as the electrooptical coefficients.[1] Furthermore the same model could successfully be applied for modeling electrical and optical properties within 90^∘ and 180^∘ domain walls in BaTiO₃.[2]

Our calculation shows that the experimental data of the spontaneous polarization and refractive indices of PbTiO₃ at room temperature are well explained by considering the nonlinearity and anisotropy of the first-, second-, and third-order electronic polarizabilities of the constituent ions, particularly those of the O_z²⁻-ions. Neverthless, the apparent deviation between calculated and measured values might be due to the existence of hybridized orbitals which were not taken into account in this work.

[1] H. Chaib et al., Nonlinear Optics 23, 97 (1999); J. Phys.: Cond. Matter 12, 2317 (2000); Phys. Rev. B 67, 174109 (2003).

[2] H. Chaib et al., Phys. Stat. Sol. (b) 233, 250 (2002).