Environmentally safe synthesis of SrBi₂Ta₂O₉and SrBi₂Nb₂O₉thin films

Abstract

The modern industry of electronic devices has driven the development of new synthesis methods for producing materials with the desired properties. Most of these methods rely on reagents and solvents that are toxic for human health and environment. For example, it has been reported that the preparation of thin films by metallorganic deposition methods (MOD) often requires noxious chemicals. SrBi 2 Ta 2 O 9 (SBT) and SrBi 2 Nb 2 O 9 (SBN) are ferroelectric compounds with important applications as non volatile ferroelectric random access memories (NVFRAM). The advantage of being lead-free compounds is partially loss if the necessary efforts for making their precursors synthesis as safe as possible are not made. In this work a new method using an ethanol-based solution and starting from the acetates of the desired cations for obtaining SBT and SBN thin films is described. The properties of the obtained films demonstrate the good quality of the so prepared materials: the remnant polarization (Pr) values are around 6 μC/cm 2 and 10 μC/cm 2 for stoichiometric SBT and SBN respectively, and the observed leakage currents stay below 3μA for applied fields of 240 kV/cm 2 . These characteristics indicate the present method to be adequate for producing ferroelectric materials with suitable properties for memories applications.