Crystal Structure and Compressibility of Pb(Zr_1−xTi_x)O₃ Ceramics Under High Pressure

Abstract

X‐ray diffraction patterns of Pb(Zr0.3Ti0.7)O3 and Pb(Zr0.7Ti0.3) O3 have been measured at pressures up to 36 GPa with good signal‐to‐noise ratio using synchrotron radiation. In order to refine the crystal structure, Rietveld analysis has been performed. The structure of Pb(Zr0.3Ti0.7)O3 is tetragonal in space group P4mm with lattice parameters a=b=3.9843±0.0003 Å and c= 4.1545±0.0003 Å at ambient pressure. A pressure‐induced phase transition was found in the pressure range higher than ∼7.4 GPa at room temperature. The high‐pressure phase is cubic in space group with lattice parameter a=3.9600±0.0003 Å at 7.4 GPa. The Birch–Murnaghan equation of state fit to the experimental data yields B0=83.9±1.7 GPa (B′0=4.0 is fixed) for tetragonal phase and B0=102.5±4.4 GPa (B′0=4.0 is fixed) for cubic phase with V0=65.95±0.01 Å3. The structure of Pb(Zr0.7Ti0.3)O3 is monoclinic in space group Cc with lattice parameters a=10.0627±0.0164 Å, b=5.8511±0.0024 Å, c= 5.7949±0.0020 Å, and β=125.185±0.119 ° at ambient pressure. No pressure‐induced phase transition for Pb(Zr0.7Ti0.3)O3 was observed over the pressure range of this study. The Birch–Murnaghan equation of state fit to the experimental data yields B0=73.6±18.9 GPa (B′0=4.0 is fixed) with V0= 278.81±0.63 Å3.