Page 18 - Chalcogenide Glasses for Infrared Optics
P. 18
Intr oduction xvii
described. Glasses have a major advantage over crystalline materials
in that they can be easily cast, molded, extruded, and drawn into
fiber. Such processes generally cannot be applied to crystalline
materials but were applied to chalcogenide glasses. Also, the
composition of a glass can be changed within limits to enhance
properties important to an application. Very little such latitude exists
with crystals. The ratios among constituent atoms of most crystalline
materials are fixed. Examples of how the composition of some glasses
was changed at AMI to enhance a property will be discussed.
Comments to the readers who are students: The author considers
himself a physical chemist. Chemistry is an applied science and mostly
empirical. Tools used while conducting a research project have
changed immensely since 1948 when this author started out, from
slide rules and burets to computers, infrared FTIR spectrophotometers,
Raman instruments, electron microscopes, and differential thermal
analysis (DTA) for glasses. Lasers were not even invented until 1959.
There was no material sciences school, only chemistry and physics.
Chemical structural theories have changed greatly based on results
from the new instruments and techniques. The language of science is
constantly changing, reflecting people’s increased understanding,
which improves their descriptions. Not nature! Nature never changes.
Avoid having a preconceived solution to a problem before you start.
Let nature guide you through the results of your experiments. Always
remember, it is the investigation that is important, not the investigator.
It is not important to be right at the start—only at the finish.