Influence of stress on the electromechanical properties and the phase transitions of lead-free (1 − x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3

Abstract

The influence of stress on the phase boundaries of polycrystalline lead-free perovskite (1 − x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 (x = 0.4, 0.5, and 0.6) was characterized through the temperature- and stress-dependent small-signal dielectric and piezoelectric response from − 150 to 200 °C under uniaxial compressive stress up to − 75 MPa. For all three compositions, the phase transition temperatures separating the rhombohedral, orthorhombic, tetragonal, and cubic phases were shifted to higher temperatures with an increase in the uniaxial mechanical loading, corresponding to a significant decrease in the dielectric and piezoelectric responses. Additional stress-dependent relative permittivity measurements up to − 260 MPa were conducted at four different constant temperatures (− 10, 10, 25, and 40 °C), revealing significant increases in the dielectric response, making these materials interesting for tunable dielectric applications. Furthermore, the stress-induced shift in phase transition temperatures was confirmed by in situ combined temperature- and stress-dependent Raman spectroscopy measurements under different constant uniaxial loads within the temperature range from 30 to 130 °C. Graphical abstract

Ionic liquid modified PVDF/BCZT nanocomposites for space charge induced mechanical energy harvesting performance

“…Room temperature Raman spectroscopy has also been employed here to investigate the structural properties. The obtained vibration modes of the Raman spectra of the synthesized BCZT powder (figure 1(d)) are in good agreement with those of previous reports [24][25][26]. The vibration bands ∼295 and 723 cm −1 are the characteristic modes of ferroelectric phases namely, rhombohedral, orthorhombic, and tetragonal [25].…”

“…The vibration bands ∼295 and 723 cm −1 are the characteristic modes of ferroelectric phases namely, rhombohedral, orthorhombic, and tetragonal [25]. The broad vibration mode within the frequency range of ∼190-260 cm −1 (combination of A 1 (TO 1 ) and A 1 (TO 2 ) modes at ∼205 and 260 cm −1 (also see the deconvolution of this broad vibration mode presented in figure S2, SI)) indicates the stabilization of rhombohedral structure within the synthesized perovskite [26]. Thus, the multi-phase co-existence in the synthesized BCZT has also been confirmed from the Raman spectroscopic characterization.…”

Stress dependent impedance spectroscopy of niobium based ceramics

“…With the increase of uniaxial stress until -300 MPa, the grain capacitance decreased by 20% for NKNZ5 and 34% for NKNZ10, whereas the grain boundary capacitance decreased by 10% and 27%, respectively. Degradation of the permittivity has been observed previously in BT, 37) Ba(Zr 0.2 Ti 0.8 )O 3 -(Ba 0.7 Ca 0.3 ) TiO 3 (BCZT), 50) NBT-6BT, 51) and NKN-based 52,53) ceramics. In general, the domain wall mobility is reduced while the material is exposed to mechanical stress.…”

Temperature‐ and stress‐dependent electromechanical properties of phase‐boundary‐engineered KNN‐based piezoceramics

“…The first derivative of permittivity can provide a better method for determining the phase-transition temperatures. 78,79 All samples show both an interferroelectric and a ferroelectric-paraelectric phase transition peak, where the interferroelectric peaks are relatively lower than that observed at the Curie temperature. In addition, peak broadening and shifting can also be seen with increased mechanical loading.…”

“…Temperatures below 0°C are not shown in Figure 3, as all phase transitions were found to occur at or above room temperature. The first derivative of permittivity can provide a better method for determining the phase‐transition temperatures 78,79 . All samples show both an interferroelectric and a ferroelectric–paraelectric phase transition peak, where the interferroelectric peaks are relatively lower than that observed at the Curie temperature.…”