Development of SrPbO3 for the growth of nanostructures: a feasibility study

The development of nanostructures is becoming increasingly important not only in the laboratory but also as commercial products. Major supermarkets now carry a large number of product lines that contain nanostructured particles or rely on nanostructuring for functionality, mainly in the health and beauty sections. A new, and exciting, technique for making nanostructures is based on ferroelectric lithography where the structures are made directly onto the patterned surface of a ferroelectric substrate using a photo activated state. This is a technique that has been developed at Cranfield University in collaboration with others, such as Prof D Bonnell at University of Pennsylvania. This proposal seeks to improve the photochemical performance of the ferroelectric by increasing the number of photoexcited holes available for reaction in the REDOX cycle. It is well known from literature and text books that the photochemistry of materials such as SrTiO3 and BaTiO3 is limited by the activity of holes. A recent paper has indicated that the material SrPbO3 has some of the characteristics required to increase the holes available in the system. It has a deep valance band at ca 7eV and a relatively small band gap of 1.8eV, these values mean that it should be possible to inject holes from the SrPbO3 into the standard photocell that consists of BaTiO3 (BT) or PbZrxTi1-xO3 (PZT). A review of the literature and text books indicates that when these characteristics are combined into a standard PZT or BT photo-cell an enhancement of the overall cell performance by as much as 30% could be expected. Cell performance will be measured using the photocurrent produced by the cell and also investigation as to the size and density of nanoparticles produced during irradiation.