The role of defects in the physical properties of mechanically activated PbTiO₃ ferroelectrics

Abstract

In this work a multi-technique characterization was performed for the first time to trace the influence of structural defects on the physical properties of PbTiO 3 ferroelectrics. The structural defects were generated by the mechanical activation in the pressure range of 40-320 MPa, by combining a uniaxial strain with a shear deformation in the Bridgman anvils. The induced defectivity of PbTiO 3 was assessed via calculation of unit cell parameters, estimation of the regions of coherent scattering and analysis of micro-deformations. The Debye characteristic temperature, the static mean-square displacement, the Debye-Waller isotropic factor, the vibrational spectra and dielectric properties of the activated PbTiO 3 ceramics are presented. The high-quality PbTiO 3 ceramics was prepared without modifiers, hence, changing the concentration of structural defects via mechanical activation constitutes a chemically clean method for fine tuning of the dielectric properties of PbTiO 3 .

Modulation of the Physical Properties of Lead Zirconate by the Stress‐Induced Structural Defects

“…It should also be noted that although the B values of the pristine materials are equal, the highest B values for the mechanically activated PZO are twice lower than those reached earlier for the similarly treated PbTiO 3 . [ 22 ]…”

“…PZO ceramics were synthesized by the solid state reaction method. [ 22 ] Briefly, chemically pure PbO and ZrO 2 were taken in a stoichiometric ratio and mixed well with the addition of ethanol in an agate mortar and pestle for 2 h. The mixture was compacted into tablets and sintered at 1200 °C (±1 °C) for 2 h in an air atmosphere in closed crucibles amid PbZrO 3 powder to restore the escaping lead oxide. The products were ground into powder for the measurements and mechanoactivation.…”

“…For the two‐temperature method, the integral intensities of the (110) and (220) reflections, I (110) and I (220) , were measured at 773 and 873 K using a high‐temperature homemade accessory for the diffractometer. [ 22 ] The plotted values were graphically connected with B‐spline lines.…”

“…We have studied the effect of structural defects (dislocations and point defects) on the physical properties of PbZr 0.58 Ti 0.42 O 3 , [ 20 ] PbZr 0.56 Ti 0.44 O 3 , [ 21 ] and PbTiO 3 [ 22 ] as well as several relaxor ferroelectrics. [ 23 ] In the studied systems, the nonideal crystal lattice not only leads to an additional attenuation of the intensity of the Bragg maxima due to static displacements, but also modifies the expression for the Debye–Waller attenuation factor, B .…”

“…Therefore, it is of practical importance to examine how the properties of PZO respond to mechanical activation. In this work, the previously developed methodology [ 20–22 ] is utilized to assess the impact of the stress‐induced structural defects on phase transitions, structural parameters, electrophysical properties, and lattice dynamics of PZO ceramics.…”