Date Awarded
2002
Document Type
Dissertation
Degree Name
Doctor of Philosophy (Ph.D.)
Department
Physics
Advisor
Henry Krakauer
Abstract
Recent experimental and theoretical work indicates that polarization rotation via a monoclinic phase at the morphotropic phase boundary in PZT is responsible for its large piezoelectric response. We performed Linearized augmented plane wave with the local orbital extension (LAPW+LO) method within local density approximation (LDA) on B-site [001]1:1 ordered Pb(Zr 0.5Ti0.5)O3 (PZT 50/50). We use a tetragonal super-cell and constrain it with monoclinic Cm space group. Atomic forces following the formulation of Yu et al. are calculated, and the conjugate gradient method is implemented to optimize the internal coordinates. Both the tetragonal (P4mm) and monoclinic (Cm) phases are reproduced, when we strain the system while keeping the volume fixed at experimental value. Bulk spontaneous polarization, Born effective charges (Z*) and piezoelectric coefficients are computed from the Berry's phase approach. The polarization rotates between the pseudo-cubic [001] and [nunu1] directions, where nu = 1.27 in the (110) mirror plane. The piezoelectric coefficients are enhanced when polarization rotation is permitted, namely e33 = 12.6 C/m2, e15 = 10.9 C/m 2, and giant absolute values of e13 = -33 C/m 2 and e'11 = 36 C/m2, where e'11, is defined as 0.5 (e11 + e12). It gives an explanation to the big piezoelectric response measured in ceramic PZT 50/50. Furthermore, the calculated internal coordinates of monoclinic phase of PZT 50/50 at experimental value of c/a are in good agreement with the experimental data of Pb(Zr0.52Ti 0.48)O3.
DOI
https://dx.doi.org/doi:10.21220/s2-x29v-9z47
Rights
© The Author
Recommended Citation
Wu, Zhigang, "First-principles calculations of piezoelectricity and polarization rotation in lead zirconate titanate" (2002). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1539623401.
https://dx.doi.org/doi:10.21220/s2-x29v-9z47
