Sadegh Asefi is spending his summer at Academia Sinica in Taiwan.

July 6, 2011

At the entrance to Academia Sinica

When I left the United States my mission was to not only help advance the field of nanotechnology but to also learn how other cultures are tackling the energy crisis. From the moment I arrived in Taiwan it was clear that meeting the energy demand here was different from back home. The first sign of this came when I noticed that nearly half of all traffic consists of motorcycles, which is very different than what we are use to in America.

Here at the Physics Institute of Academia Sinica I am working on expanding the potential of thermoelectric materials (TE); a topic in which I have great interest. These materials have the power to transform waste energy such as heat into real usable energy. Studying and producing thermoelectric materials requires much knowledge of not just how a single material behaves but how several materials with variable concentrations and nano structures affect one another when trying to produce a desirable result. Since my background is in Mechanical Engineering with an emphasis on Nanoscience, I find this topic highly relevant to what I wish to do in graduate school.

In my research, I have the privilege of working with several post doctorates, all with stellar backgrounds in nanotechnology and physics. Our daily routine consists of producing and testing of thin films TE materials. In order to produce thin films in the scale of nanometers we use a device called a sputtering machine.  This highly delicate device utilizes very low pressure (aka high vacuum) and varying deposition rates to produce the desired film thicknesses. Since sputtering is highly sensitive and prone to mistakes, a second device called the X-Ray Diffractometer (XRD)  is used to check the results obtained. The (XRD) is a highly sophisticated device that gives us a very accurate depiction of what elements are present in our samples and with what concentrations.  This allows us to determine if there are any discrepancies between the desired and actual results.

One of the main challenges facing our research is containing contaminants.  Because our samples are incredibly thin, a minute adulteration of the sample can cause significant changes to the samples crystal structure and consequently its material properties. To avoid contamination extreme caution is exercised when handling and transporting our samples.  For example, when transporting samples between laboratories, the specimens are sealed in high vacuum glass tubes.  To get an idea of the pressure within these vessels, envisage taking regular atmospheric pressure and reducing it by a factor of a million! These are the kind of measurements one must take in order to ensure that the experiment goes as planned.

With every passing day our understanding of these materials increases which will hopefully lead to the discovery of a highly efficient TE material.

August 1, 2011

This experience has taught me many invaluable lessons. For one, it has shown me how truly important prior knowledge is in scientific study and how every published paper or journal is like a stepping-stone for the next researcher in your field. But most of all, this endeavor has taught me that a scientific researchers greatest virtue is patience.  Without it, anger and frustration will set in and blind you of your objectives. I say this because we have had a lot of mechanical malfunctions with many of our experimental devices. Each of these set backs have come with a cost of as much as a few days of time. At first I became very frustrated and even a little discouraged but later I learned that malfunctions and all the set backs are an unavoidable part of research. I also learned to use this down times to do more research and come up with ways of fine-tuning our experiments.

 

 

Working on thermoelectric materials has given me an appreciation for just how much work goes into doing even the simplest tasks.  When reading research papers we are seldom told about all the mistakes, the heartaches, and ALL the late nights that have gone into the writing and the acquisition of data.

This week we finalized our specimen testing and are now ready to proceed with the measuring of relevant intrinsic properties. The measurement of these properties will be done at various temperatures to determine what is the most effective temperature for our thermoelectric material. These properties will help us determine our thermoelectric materials figure of merit ZT(efficiency).   Our data from the XRD machine currently suggests that we have made high quality thermoelectric thin films. But, nothing is for certain until the proper data has been collected.  With time running out, it’s a race against time for me to get my samples prepared and tested prior to my departure date. It is my hope that the data that I have collected in my time here can be used as a stepping stone to further expand the field of nanotechnology and pave the road towards making high efficiency thermoelectric materials part of the energy solution.