Giant piezoelectric coefficient of PNN-PZT-based relaxor piezoelectric ceramics by constructing an R-T MPB

Perovskite Relaxor‐Dependent Contributions to Piezoelectric Power Generation of Multiple PZT Tape‐Based Cantilever Structures at Nonresonant Frequency

“…As observed in the fitted patterns in the 2𝜃 range of 43°-46°in Figure 1d, increasing the relaxor content tended to change the relative position and intensity of the tetragonal and rhombohedral peaks, as similarly reported previously. [21,22,45] For example, the tetragonal peaks of the (002) and (200) planes weakened with the increasing PZN content in the highlighted PZN-PZT patterns. For 0.4PZN-0.6PZT, the tetragonal (002) and (200) planes approached one broad peak near the rhombohedral (200) peak, indicating the MPB region.…”

“…The observation of piezoelectric boosting near the MPB is undoubtedly consistent with other reported relaxor-intervened ferroelectric systems, in which the MPB region displayed superior piezoelectricity properties owing to the presence of a greater number of possible spontaneous polarization directions. [21,22,47] Interestingly, the piezoelectric parameters depended on the type of relaxor; for example, the highest d 31 value was observed for 0.4PZN-0.6PZT and the highest g 31 for 0.2PCN-0.8PZT. This discrepancy is essentially caused by the lower permittivity of ≈601 at 1 kHz for 0.2PCN-0.8PZT than ≈1981 for 0.4PZN-0.6PZT.…”

“…Similarly, the gradual peak merging of the tetragonal planes was distinctly observed in the cases of PCN and PNN, which occurred earlier with lower relaxor contents, i.e., 0.2PCN-0.8PZT and 0.2PNN-0.8PZT. [22,46] For the 0.2PCN-0.8PZT, 0.2PNN-0.8PZT, and 0.4PZN-0.6PZT compositions, the relative contents of tetragonal phase were estimated to be 37.5%, 45.0%, and 48.6%, respectively, as determined by comparing the intensities of the tetragonal (002)/(200) peaks and the rhombohedral (200) peak, as shown in Figure S1 of the Supporting Information. Changes in the grain size were monitored for the material systems, as shown in Figure S2 (Supporting Information), revealing a decreasing tendency in the grain size with the increasing content of each relaxor.…”

“…[14][15][16][17][18][19][20] In particular, the isovalent substitution of the Zr site with B +2 cations and the replacement of the Ti site with donor pentavalent B +5 have been widely studied in perovskite PZT, which have substantially improved the piezoelectric charge coefficients while maintaining strong MPB behavior. [21,22] However, limited reports exist on the use of PZT-relaxor systems as power-generation devices. [23][24][25] For example, a unimorph cantilever harvester with 0.2Pb(Zn 1/3 Nb 2/3 )O 3 -0.8Pb(Zr 0.5 Ti 0.5 )O 3 delivered a power of ≈69 μW when operated at an acceleration of 10 g and a resonant frequency of 89 Hz.…”

Field-driven merging of polarizations and enhanced electrocaloric effect in BaTiO3-based lead-free ceramics

“…The electric field and stress-driven physical properties may be used to search for the material systems with larger ECEs. Indeed, MPB was successful in achieving the greatly enhanced piezoelectric and dielectric characteristics in PZT and PMN-PT [23][24][25][26][27][28], and a theory of polarization rotation was put forward to illustrate the larger piezoelectric properties in PMN-PT and PZN-PT [29]. Although Heitmann and Rossetti [30] analyzed the phenomenological coefficients in their phenomenological theory on MPB, it is still debating if the materials at MPB may produce a larger ECE than the linear summation of temperature change times the content of each phase.…”