Lab talk
Jan 20, 2012
Humidity nanosensors made from individual metal oxide nanorods
Perovskite BaTiO3 nanorods can be synthesized and integrated into simple circuit architectures. Scientists from the Jozef Stefan Institute, the University of Barcelona, and from the Catalonia Institute for Energy Research have teamed up to characterize the material and assess its electrical properties. The polycrystalline BaTiO3 nanorods were synthesized by electrophoretic deposition (EPD) of barium titanate sol into aluminium oxide (AAO) templates and subsequent annealing. TEM observations identified the presence of slabs of hexagonal polymorphs intergrown within cubic grains, resulting from the local reducing atmosphere during the thermal treatment.
Electrical measurements performed on individual BaTiO3 nanorods revealed resistivity values between 10 and 100 Ω cm, which is in good agreement with typical values reported for oxygen-deficient barium titanate films. Consequently, the presence of oxygen vacancies in their structure was indirectly validated.
Sensing device
Some of these nanorods were tested as proof-of-concept humidity sensors. The configuration exhibited reproducible responses towards different moisture concentrations, demonstrating that individual BaTiO3 nanorods may be integrated in complex circuit architectures with functional capacities.
Further details can be found in the journal Nanotechnology.
About the author
The study was conducted by research groups of the Jozef Stefan Institute, Slovenia and Catalonia Institute for Energy Research, Spain. Dr Kristina Zagar graduated in chemistry at the University of Ljubljana, Slovenia (2006) and she received her PhD in the field of nanostructures and nanomaterials at the Jozef Stefan Postgraduate School, Ljubljana (2011). Currently she is an assistant with PhD at the Department for Nanostructured Materials at Jozef Stefan Institute, Ljubljana. Her professional experience is focused on synthesis and characterization of perovskite nanomaterials by template-assisted sol-gel electrophoretic deposition and synthesis of nanoporous alumina and titania templates by electrochemical oxidation of Al and Ti metal foils. Dr Francisco Hernández graduated in physics at the University of Barcelona, Spain (2003) and got his PhD degree in "cum laude" at the same university (2007), in the group of Prof. J R Morante. In 2009, he took a position as project manager and researcher at IREC, where he currently focuses his research on the fabrication of nanodevices with FIB and their electrical characterization. He is also part-time professor at the Department of Electronics of the University of Barcelona.
