Correlation between the piezoelectric properties and the structure of lead‐free KNN‐modified ceramics, studied by Raman Spectroscopy

Abstract

The structure of (Li,Na,K)(Nb,Ta,Sb)O 3 piezoelectric ceramics was thoroughly studied by X-ray diffraction (XRD) and Raman spectroscopy for samples with different compositions and sintered for different times. A linear relationship is evidenced between the tetragonality ratio derived from XRD and the Raman shift. The Raman stretching modes are used to demonstrate the correlation of the structure and the piezoelectric properties of the materials, and to calculate the effective ionic displacement causing the piezoelectric polarization. The methodology proposed here offers invaluable insight into the nondestructive Raman analysis of perovskite structures based on the potassium sodium niobate systems, which are not amenable by studies of diffraction or other spectroscopic techniques.

Exploring different sintering atmospheres to reduce nonlinear response of modified KNN piezoceramics

“…As reported recently, the best piezoelectric properties in KNL-NTS piezoceramics are obtained for tetragonal symmetry, and therefore a linear correlation exists between tetragonal distortion and the piezoelectric properties. 31,32 From this perspective, the development of KNN-based ceramics with a high tetragonal distortion due to the control of the sintering atmospheres could also be favorable for enhancing their piezoelectric properties.…”

Achieving high piezoelectricity and fatigue free hysteresis in lead free relaxor ferroelectric ceramic 0.94[Na0.5K0.5NbO3]–0.06LiSbO3

“…The n 1þ n 5 peak around 857 cm À1 was found blue shifted with the increasing sintering temperature. The blue shift of Raman bands implies a higher displacement of the central ion (B 5þ ¼ Nb 5þ /Sb 5þ ) from its equilibrium position which takes place due to changing lattice parameters for tetragonal structure [23,24]. The shift in the Raman peak can be attributed to the change in crystal structure from orthorhombic to tetragonal at 1090 C. Similar phase change in the Raman spectra of the NKLNS ceramic has also been observed by W.L.…”

Influence of surface modifiers on hydrothermal synthesis of K x Na(1−x)NbO3

“…The secondary nucleation of small crystals improved the surface diffusion mechanisms that promoted the formation of the characteristic rectangular KNN grains. Considering the usual densification problems of KNN, these samples present a high degree of densification [18,19]. High density values are attained in virtue of the synthesized powder, whose nanosized particles determine its reactivity.…”