Decoding the Piezo-Contributions of Potassium Sodium Niobate Ceramics

Abstract

The contributions to the piezoelectric coefficient d 33 from the intrinsic contribution, reversible low-field domain wall vibration, and irreversible domain switching and displacement of domain walls have been quantitatively investigated in potassium sodium niobate (KNN) ceramics with different phase structures. By measuring the piezoelectric coefficient at a large field and the piezoelectric hysteresis under subswitching conditions following Rayleigh relations, the intrinsic/extrinsic and reversible/irreversible piezoelectric responses are studied to understand the role of different phase boundaries in enhancing the piezoelectricity. This lattice contribution, reversible domain wall vibration, and irreversible contributions are strongly dependent on the crystal and domain structures of the examined ceramics. The intrinsic, reversible extrinsic, and irreversible extrinsic piezoelectric coefficients can both be enhanced in the phase instability regime for KNN-based ceramics. With respect to the intrinsic piezoelectric contribution ratio, ceramics with an orthorhombic-tetragonal (O-T) region have larger values as compared with those having orthorhombic (O)/ rhombohedral-orthorhombic-tetragonal (R-O-T)/rhombohedral-tetragonal (R-T) regions. For KNN ceramics, the extrinsic piezoelectric response is the major contributor to the high piezoelectricity. Strongly linked to temperature, the intrinsic contributions of O/O-T/R-O-T phases decrease first and then increase near the phase transition temperature of the O phase to the T phase in the temperature range, with an opposite tendency in R-T phases.

Contribution of irreversible non-180° domain to performance for multiphase coexisted potassium sodium niobate ceramics

“…To further explore the contribution of irreversible domain switching, Rayleigh law based on phenomenological theory is also used to reveal the origin of strain 46 – 52 . The domain structure remains unchanged with the AC field cycle of 1/2 E c to 1/3 E c during the Raleigh region, leading to an increase linearly piezoelectric constant under the sub-switching conditions 50 . Their Rayleigh relationship can be expressed as follows 50 : where S is strain value, E is the driving electric field, E 0 is the maximum electric field, d init is the initial reversible piezoelectric response, α is the piezoelectric Rayleigh coefficient, and α E 0 describes the irreversible piezoelectric response caused by the irreversible domain response.…”

“…The domain structure remains unchanged with the AC field cycle of 1/2 E c to 1/3 E c during the Raleigh region, leading to an increase linearly piezoelectric constant under the sub-switching conditions 50 . Their Rayleigh relationship can be expressed as follows 50 : where S is strain value, E is the driving electric field, E 0 is the maximum electric field, d init is the initial reversible piezoelectric response, α is the piezoelectric Rayleigh coefficient, and α E 0 describes the irreversible piezoelectric response caused by the irreversible domain response. The S – E loops are measured at an AC electric field with a maximum amplitude of 3 kV/cm after poling at a high electric field.…”

“…3f and Supplementary Fig. 9b, e ), while d 33 * is obtained according to the following equation 50 : where is the difference between positive and negative strain values. The d init first increases and then decreases with increasing Sb 5+ (Fig.…”

“…3i ). In addition, the contribution of reversible domain wall motion ( d rever-DW ) can be calculated as follows 50 : …”

“…Thus, the proportion of intrinsic contribution ( C intri ) from the lattice deformation can be calculated as 50 : …”