Today, in our Application Note series, we are covering Scanning Thermal Microscopy (SThM) - an atomic force microscopy (AFM) imaging mode that maps changes in thermal conductivity across a sample's surface. Similar to other modes that measure material properties, SThM data is acquired simultaneously with topographic data. The SThM mode is made possible by replacing the standard contact mode cantilever with a nanofabricated thermal probe with a resistive element near the apex of the probe tip. This resistor is incorporated into one leg of a Wheatstone bridge circuit, which allows the system to monitor resistance. This resistance correlates with temperature at the end of the probe, and the Wheatstone bridge may be configured to either monitor the temperature of a sample or to qualitatively map the thermal conductivity of the sample.
Ferroelectric domain patterns attract increasing attention owing to their potential for integrated optical and novel electronic applications. Lately, Piezoresponse Force Microscopy (PFM) has become a standard technique for the investigation of such domain patterns due to the high lateral resolution of only about 10 nm even - so no specific sample preparation is needed. In addition, due to the frequency modulated PFM technique for recording ferroelectric domains, topography and domain patterns can be recorded simultaneously and independently. Piezoresponse force microscopy is based on the deformation of the sample due to the converse piezoelectric effect. Generally, all scanning force microscopes are suited for PFM operation as long as they allow application of voltages to the tip and separate readout of the cantilever movement.
In today's Spotlight we take a look at a specific example of the challenges researchers face in improving fuel cell technology and the important role that modern laboratory instruments such as electron microscopes play in their work. Fuel cells have gained a lot of attention because they provide a potential solution to our addiction to fossil fuels. Energy production from oil, coal and gas is an extremely polluting, not to mention wasteful, process that consists of heat extraction from fuel by burning it, conversion of that heat to mechanical energy, and transformation of that mechanical energy into electrical energy. In contrast, fuel cells are electrochemical devices that convert a fuel's chemical energy directly to electrical energy with high efficiency and without combustion (although fuel cells operate similar to batteries, an important difference is that batteries store energy, while fuel cells can produce electricity continuously as long as fuel and air are supplied).