Investigation of piezoelectric properties in manganese doped alkaline niobate-based lead-free piezoceramics

Abstract

In this work, an attempt is made for improving the piezoelectric properties of a lead-free (Na${}_{0.5}$K${}_{0.485}$Li${}_{0.015})$(Nb${}_{0.98}$V${}_{0.02})$O₃ ceramic system by doping manganese in it. The Rietveld analysis of XRD micrographs of the ceramics indicates the samples crystallizing into 99.86% of orthorhombic phase and very small traces of tetragonal phase around room temperature. The Curie temperature ($T_c$) is hardly affected by the incorporation of Mn${}^{4+}$ into the system. At the manganese concentration of 0.02$$wt.%, the ceramic system attains the peak values in its density, dielectric constant at room temperature (${\epsilon }_{\text{RT}}$), planar electromechanical coefficient ($k_p)$, piezoelectric coefficient ($d_{33}$), and remnant polarization ($P_r$). The optimum piezoelectric properties of $k_p=43$% and $d_{33}=193$ pC/N are observed for this composition. The study reveals that the modification of (Na${}_{0.5}$K${}_{0.485}$Li${}_{0.015}$) (Nb${}_{0.98}$V${}_{0.02})$O₃ with an appropriate quantity of Mn${}^{4+}$ can produce the desired changes in the crystallographic properties and densification so as to eventually improve its piezoelectric properties.