Correlation Between Piezoelectric Properties and Phase Coexistence in (Ba,Ca)(Ti,Zr)O₃ Ceramics

Abstract

High piezoelectric properties are desired for lead‐free piezoelectric materials in consideration as a replacement for lead‐based materials in applications. Due to the high piezoelectric coefficient, (Ba100−xCax) (Ti100−yZry) O3 (BCTZ) piezoelectric ceramics have been considered as a promising lead‐free alternate piezoelectric material. Here, six compositions were selected based on a prediction that all the compositions would have high piezoelectric coefficient at room temperature. The results confirmed all compositions exhibit well developed hysteresis loops and a large piezoelectric coefficient at room temperature. This is due to the coexistence of several phases where the major phase is likely to be orthorhombic and the second phase is proposed to be tetragonal. The phase transition was found to occur over a broad temperature range instead of at a specific temperature only. A relationship between the tetragonal–orthorhombic phase transition temperature and Ca2+ and Zr4+ content was proposed. This enables clear determination of BCTZ compositions with high piezoelectric coefficient at a desired operation temperature.

Phase transitions and phase diagram of Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 Pb-free system by anelastic measurement

“…However, because there is strong coupling between lattice distortions (strain) and the ferroelectric order parameter (polarization), it is inevitable that there will be changes in elastic and anelastic properties associated with the discrete phase transitions in the BZT-xBCT lead-free system. [34][35][36] The real part of the elastic response to a dynamic stress field, expressed as the storage modulus (E 0 ), is the inverse of the mechanical susceptibility. The imaginary part of the response is the loss modulus (E 00 ).…”

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

“…The temperature decay of is enlarged after crossing the various phase boundaries, in agreement with previous works. 194,305 This is expected considering that excursions across PPBs diminish the poling state of ferroelectrics. 150 Literature reports have indicated that generally the properties of the R phase are much more susceptible to temperature and poling treatments.…”

“…194,320,325 Electromechanical properties were found to have local maxima values around phase boundaries, followed by diminished properties. 194,305 Higher temperature stability was generally observed away from phase boundaries, although with diminished magnitudes. 317 At room temperature it was demonstrated that 4 kV/mm lead to saturation of the poling degree given by angle.…”

“…159,193 In polycrystalline materials, however, extrinsic contributions and intergranular constraints can play a considerable role on the electromechanical properties, as shown for BZT-BCT in Section 5.1.3.2.3 and in the literature. 302,305,306 Further features of the BZT-BCT recall for a reconsideration even of its ferroelectricity due to the presence of features common to relaxor materials. Based on considerations from literature and the results from the current work, a complete model that accounts for intrinsic and extrinsic contributions to the electromechanical response of BZT-BCT was developed to reconcile all the experimental observations.…”

Outstanding Photoluminescence in Pr3+-Doped Perovskite Ceramics

“…For instance, Zhang et al obtained a piezoelectric constant d 33 as high as 200 pC/N by introducing Zr 4+ dopant in (Ca, Ba) TiO 3 [21]. Zhang et al reported (Ba, Ca) (Ti, Zr) O 3 (abbreviated as BCTZ) ceramics which have high piezolelectric and ferroelectric properties [22]. Liu et al reported a BCTZ ceramic which has a high piezoelectric constant d 33 (~620 pC/N) [23].…”