• Azough, Feridoon
• Lin, Yue
• Kinloch, Ian A.
• Simpson, Kevin
• Norman, Colin
• Wang, Li
• Srivastava, Deepanshu
• Robbins, Mark
• Freer, Robert

Abstract

The applications of strontium titanium, oxide based;thermoelectric materials are currently limited by their high operating temperatures of >700 degrees C. Herein, we show that the thermal operating window of lanthanum strontium titanium oxide (LSTO) can be reduced to room temperature by the addition Of a small amount of graphene. This increase in operating performance will enable future applications such as generators in vehicles and other sectors. The LSTO composites incorporated one percent or less of graphene and were sintered tinder at argon/hydrogen atmosphere. The resultant materials were reduced and possessed. a multiphase Structure with nanosized grains. The thermal conductivity of the nanocomposites decreased upon the addition of graphene, whereas the electrical conductivity and power factor both increased significantly. These factors, together with a moderate Seebeck coefficient, meant that a high power factor of similar to 2500 mu Wm(-1) K-2 was reached at room temperature at a loading of 0.6 wt % graphene. The highest thermoelectric figure of merit (ZT) was achieved when 0.6 wt % graphene was added (ZT = 0.42 at room temperature and 0.36 at 750 degrees C), With >280% enhancement compared to that of pure LSTO. A preliminary 7-couple device was produced using bismuth strontium cobalt oxide/graphene-LSTO pucks. This device had a Seebeck coefficient of similar to 1500 mu V/K and an open voltage Of 600 mV at a mean temperature of 219 degrees C.

Topics

• nanocomposite
• grain
• laser emission spectroscopy
• Strontium
• Hydrogen
• Lanthanum
• titanium
• cobalt
• thermal conductivity
• electrical conductivity
• Bismuth