Page 271 - Chalcogenide Glasses for Infrared Optics

246 Cha pte r T e n

coatings on each side served as the fuel electrode and the oxidizing
electrode. The electrolyte filling the pores in the MgO disk was sodium-
lithium-carbonate. The cell body was stainless steel. Fuel used was
methane or hydrogen with O -CO in the other chamber. To prove the
2 2
cell worked, a child’s toy electric airplane was mounted in the lab with
the propeller powered by the fuel cell continuously. Methane (CH ) is
4
the most stable organic molecule from a thermodynamics standpoint.
To generate reasonable output while utilizing hydrocarbon fuels, 800°C
operation was required. Components would not last over time at such
high temperatures. The replacement of the MgO disk to reduce inter-
nal resistance and increase output in an improved “screen cell” version
was conceived and tested by the author as described in U.S. Patent
3,251,718. It was obvious that without a different fuel cell approach, the
program would last only as long as the government funding was avail-
able, much like the conditions that exist today.
In 1961 at author request, the first on and first off fuel cell pro-
gram, was transferred to the Central Analytical Chemistry Facility
under Phil Kane. The job opening was for the application of infrared
spectroscopy techniques to semiconductor materials. The instrument
available for use was the Perkin Elmer 13 U, a research-type instru-
ment at that time. It was modified so that absolute reflection from the
surfaces of semiconductor materials could be measured with polar-
ized light or plain as a function of angle of incidence and monochro-
matic wavelength. The photoconductivity of semiconductor materials
could be measured at different wavelengths and correlated with
impurity analysis. The instrument also served as the source of mono-
chromatic light for the infrared refractometer attachment used for
index measurements as discussed earlier.
The first material evaluated was beta silicon carbide film grown in
a process at TI. The question was, Is it a good infrared optical material?
The infrared evaluation of SiC films showed the answer was no.
Another investigation concerned the effect on the optical and electrical
properties of the oxygen impurity in silicon. The magnitude of the
absorption coefficient at 9 µm was correlated with the absolute concen-
tration as measured by other means. Another materials research
program active at that time under Louis Bailey was finding new ther-
moelectric materials. One studied very extensively was silicon telluride,
Si Te . The material had a layered mica structure and was transparent
2 3
in the infrared. It was while studying this material that Werner Beyen
of TI learned that the physics branch of the Office of Naval Research in
Washington was interested in funding work for the development of
new infrared optical materials. Werner Beyen once had worked for the
Office of Naval Research. The author was given the assignment by Tom
Burkhalter to develop a proposal to respond to this request. In the
TI library a copy of the 1959 proceedings of the Russian Ioffee Institute 1
was found thatcovered papers describing amorphous semiconductors.
The institute in Leningrad (St. Petersburg again now) was headed by