The effect of sintering processes on the properties of Mn-F doped PZT ceramics

Fluoridated PZT ceramics were produced by solid-state and liquid-phase sintering methods, according to the formula Pb(Zr0.52Ti 0.48)1-xMnxO3-yFy, where 0 <x <0.015 and 0 <y <0.1. The effects of sintering processes on the phase development and microstructure of Mn-F doped PZT ceramics have been investigated using XRD and FEGSEM. In solid-state sintering, the fluoride additive enhanced the densification of PZT ceramics, enabling densification to >95% relative density at a temperature as low as 1000°C. However, fluoride loss at high temperatures was found to be a significant problem. Alternatively, ceramics with a density >92% were prepared by sintering at a temperature of 850°C by incorporating a eutectic mixture of PbO and V 2O5 as sintering aid. Problems associated with volatilization of fluoride compounds during sintering could be alleviated using this approach. EPMA was employed to analyze the distribution of the additives in the calcined powders and sintered ceramics. The nonlinear dielectric properties were determined by measuring P-E loops, using an AC electric field in the range 0.1 to 2.0 kV mm-1

EXAFS study on the site preference of Mn in perovskite structure of PZT ceramics

Synchrotron extended X-ray absorption fine structure (EXAFS) measurements at the Mn K edge were performed on Mn-doped PZT ceramics with Mn concentrations of 0.5, 1.0 and 2.0 mol%. The Fourier transforms of EXAFS structures from all samples are similar and agree well with the model of Mn substituting on the Ti/Zr site (i.e. the B site of the perovskite ABO3 structure). This shows that Mn predominantly substituted for Ti/Zr in the range of concentration under study. © 2007 Elsevier Ltd and Techna Group S.r.l

A high energy synchrotron x-ray study of crystallographic texture and lattice strain in soft lead zirconate titanate ceramics

The crystallographic structure and lattice strain in soft lead zirconate ceramics were investigated using high energy synchrotron x-ray diffraction measurements. It was found that the lattice spacing and the intensity ratio varied linearly as a function of sin2ψ, for the tetragonal phase, where ψ being the angle between the plane normal and the macroscopic polar axis. The tetragonal and rhombohedral plane spacings monitored the intergrannular stress. These tetragonal and rhombohedral reflections were found to be sensitive only to the macrostrain of the polycrystal

Micromechanics of domain switching in rhombohedral PZT ceramics

The lattice strain ε{2 0 0} and diffraction peak intensity ratio R{1 1 1} have been determined in soft rhombohedral PZT ceramics during the application of an electric field up to 2.5 MV m-1 and as a function of the grain orientation ψ, using high energy synchtron X-ray diffraction. The magnitude of both ε{2 0 0} and R{1 1 1} increased sharply beyond a field level of 1 MV m-1 due to the onset of ferroelectric domain switching. ε{2 0 0} exhibited a near linear dependence on cos2 ψ, in agreement with previous studies of the remanent-poled state. In contrast, the R{1 1 1}-cos2 ψ plot showed evidence of saturation in ferroelectric domain switching, particularly for ψ > 60°. The development of lattice strain during poling is discussed in terms of contributions from the intrinsic piezoelectric effect and from residual stress caused by differences in the poling strain of a grain, and the piezoelectric strain of a grain relative to its surroundings. © 2007 Elsevier Ltd and Techna Group S.r.l

Analysis of elastic strain and crystallographic texture in poled rhombohedral PZT ceramics

The elastic strain and crystallographic texture of a rhombohedral lead zirconate titanate ceramic have been characterised in the remanent state, after poling, using high-energy synchrotron X-ray diffraction as a function of the grain orientation ψ relative to the poling direction. It is observed that the (2 0 0) diffraction peak exhibits pronounced shifts as a function of ψ, indicating an elastic lattice strain, while others ({1 1 1}, {1 1 2} and {2 2 0}) show marked changes in intensity as a result of preferred ferroelectric domain orientation. It is shown that the (2 0 0) peak is not affected by the domain switching itself but rather acts like an elastic macrostrain sensor. A simple Eshelby analysis is used to demonstrate that both the elastic strain and texture vary systematically with ψ according to the factor (3cos2 ψ - 1). This angular dependence is evaluated through micromechanics modelling. The physical meaning of the texture variations with ψ is also discussed. © 2006 Acta Materialia Inc