The modern world faces many challenges in overcoming our reliance on fossil fuels as an energy source, and simultaneously addressing the issue of climate change. Thermoelectric devices represent a viable path for improving energy efficiency through the capture and conversion of waste heat to electricity. Yet while these devices present large advantages they also face large drawbacks, such as low efficiency, high cost, and low stability across large temperature ranges. One method of addressing these problems is via nano-structuring.
One material of interest to the research community is strontium titanate (SrTiO3), a versatile material that has seen use in the fields of memristors, capacitors and photovoltaics. SrTiO3 is also one of the best thermoelectric oxide candidates, stable up to 1700°C and cheap to fabricate. The aim of this investigation is to gain control over the morphology of SrTiO3 nanostructures via the control of specifically processed SrTiO3 templates. This templating approach is unique, and offers a simple and convenient method for tuning SrTiO3 nanostructures.
SrTiO3 powder was synthesized via the sol-gel method with subsequent calcination to remove organic waste. Commercial powder was also acquired to use as a standard. Powders were then processed into templates via classical sintering methods and subsequently annealed at 1000°C in a controlled atmosphere to impose specific nonstoichiometry. Nanostructures were grown on the surface of these templates using the hydrothermal method.
SrTiO3 has been successfully synthesized. The presence of SrCO3 in the synthesised powders has proven problematic for producing highly dense templates and has driven a need to comprehensively revise both the sol-gel route and the calcining schedule in order to minimize the SrCO3 generated and maximize the density of sintered templates. TGA/DSC has been used extensively to reveal the complex relationship between the calcining temperature and time, and the presence of residual SrCO3.