  Lead-free ceramics (K0.44+xNa0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3+x/2 (x=-0,06)
were prepared by conventional solid state sintering. The results indicate a
correlation between crystalline symmetry and electrical properties. Higher
tetragonality was observed in samples with higher piezoelectric response. As
the tetragonality increase the presence of polymorphic phase decrease
associated with a reduction of the relaxor behaviour response. The ceramics
with c/a = 1.011 ratio exhibit enhanced electrical properties. The Raman
spectroscopy showed a certain asymmetry in the paraelectric phase above the
Curie temperature Tc that provokes retention of the polarization. The
crystalline symmetry plays a crucial role in the piezoelectric properties of
the system.
