Synthesis of Na _0.5 K _0.5 NbO ₃ Piezoelectrics by a Solution Coating Approach

The solution coating method is shown to provide more homogeneous mixing of the starting powders and purer (Na _0.5 K _0.5 )NbO ₃ (NKN) powder than the conventional method thereby rendering cold isostatic pressing unnecessary. Sintering NKN with potassium copper niobate (KCN) by uniaxial pressing gave a relative bulk density of 92%, d ₃₃ coefficient of 112 pC/N and a loss factor of 1% after 6 h at 1100°C. In contrast, the conventional method yielded 84% relative bulk density and a 31% loss factor after 6 h at 1100°C and the sample was too porous to allow for dielectric and piezoelectric measurements.