High performance lead-free piezoelectric 0.96(K_(0.48)Na_(0.52))NbO_3-0.03[Bi_(0.5)(Na_(0.7)K_(0.2)Li_(0.1) )_(0.5)]ZrO_3-0.01(Bi_(0.5)Na_(0.5))TiO_3 single crystals grown by solid state crystal growth and their phase relations

摘要

0.96(K_(0.48)Na_(0.52))NbO_3-0.03[Bi_(0.5)(Na_(0.7)K_(0.2)Li_(0.1) )_(0.5)]ZrO_3-0.01(Bi_(0.5)Na_(0.5))TiO_3 single crystals were grown for the first time by the solid state crystal growth method, using [001] or [110]-oriented KTaO_3 seed crystals. The grown single crystal shows a dielectric constant of 2720 and polarization-electric field loops of a lossy normal ferroelectric, with P_r = 45 μC/cm~2 and E_c= 14.9 kV/cm, while the polycrystalline samples with a dielectric constant of 828 were too leaky for P-E measurement due to humidity effects. The single crystal has orthorhombic symmetry at room temperature. Dielectric permittivity peaks at 26 C and 311°C, respectively, are attributed to rhombohedral-orthorhombic and tetragonal-cubic phase transitions. Additionally, Raman scattering shows the presence of an orthorhombic-tetragonal phase transition at ~150°C , which is not indicated in the permittivity curves but by the loss tangent anomalies. A transition around 700°C in the high temperature dc conductivity is suggested to be a ferroelastic-paraelastic transition.