[bakerbg]

Someone told me that SiO_2(s) conducts electricity when heated due to the presence of the "semiconductor" element silicon. I am unable to find any supporting document on the web. Can anyone explain how this happens, please!

[DevaDevil]

when heated (above, say, 600^oC) Silicon dioxide increases its ( verylimited) conductivity. Think in the order of about 10^-10 - 10^-6 Ohm^-1.cm^-1.


Srivastava et al., J. Electrochem. Soc. Vol. 132, No. 4 (1985) p. 955
At room temperature of course it is an insulator (glass)


The authors of this paper attribute the higher conductivity at high temperatures to contributions of ionic conductivity. Basically, they say the oxygen atoms (ions) can move around in the material at such high temperatures and generate charge movement (conductivity) that way. (they also discuss the effect of support --in their case p or n-doped silicon--, which can help create oxygen vacancies and increase conductivity as well.)


So not so much the influence of silicon as the influence of oxygen!

[bakerbg]

Very interesting DevaDevil. I appreciate the obvious effort it must of taken to get this info. I actually got this question on my 1st year Chemistry A-Level external exam. The info you provided convince me that this is beyond my level right now - for I don't understand a thing! So I will, for the time being, settle for SiO₂ being a nonconductor of electricity!

Thanks, very intersting...