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.

Prepare a solution of 5 g SnCl45H2O dissolved in 5 mL methanol. Do not use anhydrous SnCl4(l) since it reacts violently with methanol.
Assemble the concentric glass nebulizer or obtain a mister.
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
  • 600 degree C oven
  • 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