Manufacture and measurement of combinatorial libraries of dielectric ceramics: Part I: Physical characterisation of Ba1−xSrxTiO3 libraries

The application of combinatorial methods to materials science offers the opportunity to accelerate the discovery of more efficient dielectric ceramics. High throughput methods have the potential to investigate the effects of a wide range of dopants on the dielectric properties, and to optimise existing systems, encouraging the short innovation cycles that the communications technology industry requires. The London University Search Instrument (LUSI) is a fully automated, high-throughput combinatorial robot that has the potential capability to produce 1000's of sintered bulk ceramic samples with varying composition in 1 day, as combinatorial libraries on alumna substrates. The LUSI robot was demonstrated to be able to automatically print and sinter libraries of bulk ceramic Ba1−xSrxTiO3 (BST), for x = 0–1 in steps of 0.1. The samples were prepared from inks consisting of suspensions of BaTiO3 and SrTiO3 nanopowders, stabilised with 1.2 wt% dispersant. The samples were printed as arrays of 22 2mm diameter dots, two of each composition, on alumina substrates. These were then sintered at 1350 and 1400 °C/1 h by LUSI. EDXA and XRD confirmed the compositional gradient throughout the libraries, and SEM showed the samples to be well sintered, with a large 20 μm grain size for pure BaTiO3 decreasing rapidly for increasing x values.