Structural, Dielectric, and Pyroelectric Properties of (1−x)PbSc_0.5Ta_0.5O₃–(x)PbHfO₃ Ceramics

Abstract

The solid solutions of (1−x)PbSc0.5Ta0.5O3–(x)PbHfO3 (PSTH(x)) with pure perovskite structure were fabricated by hot‐pressing sintering method. The structural, dielectric, and pyroelectric properties of the PSTH(x) ceramics were investigated. It was found that the long‐range ordering decreased and the grain size increased with the increase of x. The maximum dielectric constant of 21 000 at 100 Hz and the highest pyroelectric coefficient of 615 × 10−8 C·(cm2·K)−1 were obtained for an x value of 0.15, where the PSTH(x) ceramic showed the largest lattice distortion.

The Phase Transition Behavior of (1−x)Pb(Sc0.5Ta0.5)O3-(x)PbHfO3 Ceramics

“…Under zero bias, the calculated values of γ lie between 1.5 and 1.7 and show an increase in the diffuseness of the transition with the increase of Hf 4+ substitution, which maybe result from the decrease of the B site ordering that had been reported in our previous work in Liu et al 10 When dc bias is applied, the values of γ monotonically decrease. For PSTH(0) and PSTH(0.05) ceramics, 14% and 62% volume of the materials remain disordered, respectively 10 . In the disordered regions of the two samples, the symmetry of the polarization is disturbed by the structural inhomogeneity, which results in weak dipole coupling.…”

“…spots (denoted as α‐spots 11 ), are presented in PSTH(0), while no superlattice spots can be seen in PSTH(0.10). It indicates that PSTH(0) is partially ordered and PSTH(0.10) is completely disordered, which has been confirmed by X‐ray diffraction analysis 10 . According to the scale of the ordering of B site cations, Randall et al 12 had classified the complex perovskites into three groups: (I) perovskites possessing no detectable order (<2 nm), (II) ordered with long coherency (≥100 nm), and (III) ordered but on a nanoscale (2–50 nm) or short coherency.…”

“…2. In the PSTH( x ) solid solutions, two or three different ions share the B cation site, 10 and the chemical ordered/disordered regions occur as a consequence of the fraction of Sc 3+ /Hf 4+ /Ta 5+ ions on the B site crystallographic position. As a result, broad dielectric peaks and diffuse phase transition are observed.…”

“…The PSTH( x ) powders ( x =0, 0.05, and 0.10) were synthesized by the columbite precursor method. The process had been detailed in our previous work 10 . The microstructure was examined by a field‐emission TEM (JEM‐2100F, JEOL, Tokyo, Japan) at room temperature.…”

“…In our previous work, PSTH( x ) solid solutions have also been found a variable structural ordering where 0≤ x ≤0.10 that the ordering degree decreases with the increase of x , and when x =0.10, it becomes completely disordered. And the dielectric properties under zero bias and pyroelectric coefficient of the poled materials has also been investigated 10 …”