Effect of stoichiometry and milling processes in the synthesis and the piezoelectric properties of KNN-modified nanoparticles by solid state

9 páginas, 10 figuras, 2 tablas.Nanoparticles in the system (K,Na,Li)(Nb,Ta,Sb)O3, modified KNN, were synthesized following a solid state reaction procedure. Milling of the individual carbonate and oxide raw materials was carried out before mixing of the components to optimize particle size. These mixtures were calcined at 700 ◦C for 2 h, obtaining nanoparticles with size ranging between 50 and 200 nm. The optimization of the raw materials particle size and the particle refinement of the carbonates during their decomposition play a key role in the formation of the modified KNN nanoparticles by solid state route. The obtained nanoparticles show tetragonal and orthorhombic phases coexistence that could be attributed in part to the lack of homogeneity of cations distribution confirmed by EDS analysis. The K+ cation excess on the modified KNN system produces a displacement of Li+ cations from the perovskite structure that is the origin of the stabilization of the orthorhombic symmetry. These nanoparticles are used to sintered ceramics with good piezoelectric properties without needing of anisotropic preparation methods. The sintered ceramics show resistance to hygroscopicity and deliquescence.The authors express their thanks to the CICYT projects MAT2007-66845-C02-01 and to the MAGIN project PIF2006-60f0121 for their financial support. Dr. F. Rubio-Marcos thanks the FPI-CAM-FSE program for the research grant. Dr. J.J.Romero is indebted to CSIC for a “Junta de Ampliación de Estudios” contract (ref. JAEDOC087).Peer reviewe