In this work, it was found that exposure of barium carbonate to carbon diox
ide (0.003%-5%) as active gas in wet synthetic air as carrier gas leads to
an increase in work function between 50 and 150 meV at room temperature. Ot
her carbonates show a similar behaviour and lower sensitivities. Without hu
midity in the carrier gas, the sensitivity of barium carbonate disappears.
Measurements were performed on pressed pellets, thick films (10-100 mu m) a
nd thin films (1-2 mu m) of the material using a Kelvin probe with gold gri
d as reference electrode. The effect was found to be independent of prepara
tion. Between 23 degrees C and 100 degrees C, maximum sensitivity is reache
d at about 50 degrees C. The work function change is attributed to the form
ation of dimeric HCO3- species which have been identified using diffuse ref
lectance infrared fourier transform (DRIFT) spectroscopy. (C) 1999 Elsevier
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