Heath Stewart (2005) and Josh Keane (2002)
studied diffusion of impurities in silver
chloride. Heath's impurity was cadmium and Josh's impurity was calcium.
They obtained a radioactive isotope of the impurity dissolved in an acidic
solution. They put several drops of the solution on the top surface of a
cylindrical sample of silver chloride. Then they placed the crystal in a hot
furnace for several hours.
They used sandpaper to grind down the crystal
to obtain a graph of activity as a function of depth
from the surface. After multiple trials at different temperatures,
we were able to create an Arrhenius plot, which gave us
a value for the activation energy for the particular impurity.