Mn-modified (K(0.5)Na(0.5))(0.96) Sr(0.02)NbO(3) lead-free piezoelectric ceramics

Dense lead free ceramics of (K(0.5)Na(0.5))(0.96) Sr(0.02)Nb(1-x)Mn(x)O(3) (x=,0.0,0.0,0.0,0.04) were successfully prepared by a conventional mixed oxide method. The X-ray diffraction patterns revealed pure peroveskite structure after Mn doping as compared to the original composition. This was attributed to the inhibition of K(+) volatility during sintering process. Dielectric anomaly was observed and explained by multiple-cell structure resulting from Mn-induced lattice distortion. Low loss tangent and relatively high planar electromechanical coupling factor were obtained at x=0.02. The main parameters for the composition of x=0.02 are: epsilon(33)(T)/epsilon(0)=479, d(33)= 121pC/N K(p)=41%, Q(m)=298, tandelta=1.6%, T(c)=391 deg C. The rates of resonant frequency variation, alpha(fr), and planar coupling factor variation, alpha(KP), with temperature are-1.85% and 1.19% at 80 deg C, respectively. This material may be suitable for applications in ultrasonic transducers.