Influence MnO_2 on the Properties of (Li_xNa_yK_(1-x-y))NbO_3 Ceramics

摘要

Lead-free piezoelectric ceramics lithium sodium potassium niobate (Li_xNa_yK_(1-x-y))NbO_3 (LNKNl00x/l00y) have been synthesized by a conventional solid state process. The effects of MnO_2 addition on the properties of (Li_xNa_yK_(1-x-y))NbO_3(x=0.06,y=0.5)(LNKN6/50) ceramics were investigated. It was found that a morphotropic phase boundary (MPB) between orthorhombic and tetragonal phases is in the composition range 0.05<.x<0.07. The piezoelectric constant d_(33) and the planar electromechanical coefficient k_p of LNKN6/50 ceramics reach 222pC/N and 39%, respectively. As the amount of MnO_2-doped increases, dielectric constant, piezoelectric constant and Curie temperature T_c of LNKN:Mn ceramics decreased, while mechanical quality factor Q_m of LNKN6/50:Mn increased prominently compared to pure LNKN6/50 ceramics. The addition of MnO_2 can also decrease the sintering temperature effectively of LNKN6/50 ceramics.