Pressure tuning of the morphotropic phase boundary in piezoelectric lead zirconate titanate

Titanium-rich $\mathrm{PZT}$ solid solutions were studied under high pressure by neutron and x-ray diffraction, Raman spectroscopy and dielectric measurements. The results show that high pressure stabilizes the ferroelectric monoclinic phases, which are proposed to be responsible for the high piezoelectric properties characteristic of the morphotropic composition ${\mathrm{PbZr}}_{0.52}{\mathrm{Ti}}_{0.48}{\mathrm{O}}_3$. Pressure may thus be used to tune the morphotropic phase boundary in the composition-pressure plane to include a wide range of titanium-rich $\mathrm{PZT}$ compositions.

Figure 1

(a) Raman spectra for the tetragonal $F_T$, monoclinic $F_M\left(Cm\right)$ and $F_M\left(Cc\right)$ phases of ${\mathrm{PbZr}}_{0.40}{\mathrm{Ti}}_{0.60}{\mathrm{O}}_3$ as a function of pressure. (b) Pressure dependence of the Raman modes. Arrows indicate the strongest peaks arising from cell doubling.

Figure 2

Pressure-composition phase diagram of $\mathrm{Ti}$-rich $\mathrm{PZT}$ obtained from x-ray diffraction (∎), Raman spectroscopy (◆) and dielectric measurements (●). Inset, pressure dependence of $1∕{\epsilon }_r^{\prime }$ at $100\mathrm{kHz}$ for ${\mathrm{PbZr}}_{0.40}{\mathrm{Ti}}_{0.60}{\mathrm{O}}_3$ on compression (▴) and decompression (▿).

Figure 3

Experimental and calculated profiles from the Rietveld refinement of the monoclinic $F_M$ $\left(Cm\right)$ phase of ${\mathrm{PbZr}}_{0.40}{\mathrm{Ti}}_{0.60}{\mathrm{O}}_3$ at $2.7\mathrm{GPa}$. The difference profile is on the same scale. Vertical ticks indicate the calculated positions of the $Cm$ phase (top) and of tungsten carbide (bottom) from the anvils of the pressure cell.

Figure 4

Experimental and calculated profiles from the Rietveld refinement of the monoclinic $F_M$ $\left(Cc\right)$ phase of ${\mathrm{PbZr}}_{0.40}{\mathrm{Ti}}_{0.60}{\mathrm{O}}_3$ at $4.1\mathrm{GPa}$. The difference profile is on the same scale. Vertical ticks indicate the calculated positions of the $Cm$ phase (top) and of tungsten carbide (middle) and nickel (bottom) from the anvils of the pressure cell. Due to the closer approach of the anvils at this higher pressure, the WC reflections are more intense and very weak reflections due to the Ni binder can be detected. The strongest superlattice reflection is shown in the inset. Arrows indicate the most prominent superlattice reflections.