Procedure modified by D. Keefer, E. Eibergen and G. Lisensky
from that of J. Tanaka and S. L. Suib, "Surface conductive glass," J. Chem.
Educ.61, 1104 (1984).
Reduction of tin(IV) on a hot surface gives a mixture of SnO and SnO2. The rutile lattice structure of the product can be pictured as that of SnO2 with some oxide ions missing. This non-stoichiometric oxide is a semiconductor. Related coatings are used for flat panel displays.
Procedure
Wear eye protection
Chemical gloves recommended
Fumehood recommended
Thermal gloves recommended
Prepare a solution of 5 g SnCl45H2O dissolved
in 5 mL methanol. Do not use anhydrous SnCl4(l) since it reacts
violently with methanol.
Put a ceramic tile glazed side up in an oven to serve as a liner.
Preheat the oven to 600 degrees C.
Put glass microscope slides on another ceramic tile and place in the oven.
After heating the glass and tile for 10 minutes, remove both from the oven, immediately
spray with a fine mist of tin(IV) chloride solution, and return the glass
and tile to the oven for 2 minutes to reheat.
Repeat the treatment several times as the tin(IV) chloride is reduced
by methanol on the hot surface to give a mixture of SnO and SnO2.
The rutile lattice structure of the product can be pictured as that of
SnO2 with some oxide ions missing. This non-stoichiometric
oxide is a semiconductor whose conductivity depends on the quantity of
defects. Doping with Sb(III) can act to produce
missing oxides in the structure and increase the conductivity.
Do resistance measurements for the glass follow Ohms Law? How could you
test whether the material is a metal or a semiconductor? How transparent
is your conductor?
Materials
SnCl45H2O dissolved in methanol (1 g/mL) sprayer options
ceramic tiles
microscope slides
tongs
Optional: 0.10 g Sb2O3 dissolved in 1 mL conc HCl
and then added to 5 mL of the tin(IV) chloride solution.
