Environmentally-friendly magnetoelectric ceramic multilayer composites by water-based tape casting

Magnetoelectric composites are an enabling material technology for a range of novel devices like electrically-tunable magnetic microwave components or room-temperature-operation high-sensitivity magnetic sensors. Among the different approaches under development, cofired ceramic layered composites provide large effective magnetoelectric coefficients and improved reliability. However, miniaturization and processing up-scaling remain an issue. This can be addressed by using tape casting technology to prepare multilayer structures, as it is industrially done for multilayer ceramic capacitors. We report here the processing of ceramic multilayer composites of environmentally-friendly piezoelectric (K0.5Na0.5)(0.96)Li0.04Nb1-yTayO3 and magnetostrictive CoFe1.75Mn0.25O4 by water-based tape casting. Dense ceramic multilayers with high quality interfaces were obtained, and their functional response characterized. Effects of the multilayer geometry, characterized by ceramic layer thickness of tens of microns and large number of layers, have been defined. A distinctive enhancement of functionality as compared with conventionally-prepared layered structures is demonstrated and related to strain/stress relaxation characteristics across layers. (AU)