High throughput synthesis and characterization of the PbnNb2O5+n (0.5 < n < 4.1) system on a single chip

Most high throughput studies focus on assessing the effect of composition within a single known fundamental structure type, such as perovskite. Here we demonstrate how high throughput synthesis and screening can be used to establish structure property relations in the PbO-Nb2O5 system, for which eight distinct fundamental structure types are known to exist. PbNb4O11, PbNb2O6 and pyrochlore could be easily distinguished by X-ray diffraction (XRD). However, XRD was insensitive to distortions of the pyrochlore structure and instead Raman spectroscopy was utilized to determine changes in symmetry from cubic to rhombohedral as the Pb0 concentration increased. High throughput screening of the capacitance revealed permittivity (epsilon(r)) maxima in the PbNb4O11 (epsilon(r) = 700) and cubic pyrochlore phases (epsilon(r) = 450). The epsilon(r) of PbNb4O11 has not to date been reported but the value for cubic pyrochlore is higher than that reported for bulk ceramics (epsilon(r) = 270). Initial high electric field studies also revealed exceptionally high tunability (four times that reported for bismuth zinc niobate-based pyrochlores) of the capacitance in the pyrochlore phase. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.