Effect of MnO on the phase development, microstructures, and dielectric properties of 0.95Na0.5K0.5NbO3-0.05LiTaO3 ceramics

Lead-free piezoelectric ceramics in the system 0.95Na(0.5)K(0.5)NbO(3)-0.05LiTaO(3) were modified with <= 1 mol% MnO. Maximum densities occurred at a sintering temperature of 1050 degrees C. Characteristic changes in the relative intensity of X-ray diffraction peaks were consistent with Mn ions substituting on the perovskite lattice to produce a change from orthorhombic to a mixture of tetragonal and orthorhombic phases. Grain growth during secondary recrystallization was also affected, leading to increased grain sizes. The dielectric constant increased from similar to 600 in unmodified ceramics to similar to 1040 in ceramics prepared with 0.5 mol% MnO.