Sol-gel synthesis of mesoporous CaCu3Ti4O12 thin films and their gas sensing response

RODRIGO PARRA; RALUCA SAVU; LEANDRO ALDREDO RAMAJO; MIGUEL PONCE; JOSÉ ARANA VARELA; MIRIAM SUSANA CASTRO; PAULO BUENO; E JOANNI

JOURNAL OF SOLID STATE CHEMISTRY

Elservier Ltd.

Año: 2010 vol. 183 p. 1209 - 1214

0022-4596

A new sol-gel synthesis procedure of stable calcium copper titanate (CaCu3Ti4O12 - CCTO) precursor sols for the fabrication of porous films was developed. The composition of the sol was selected in order to avoid the precipitation of undesired phases; ethanol was used as solvent, acetic acid as modifier and poly(ethyleneglycol) as a linker agent. Films deposited by spin-coating onto oxidized silicon substrates were annealed at 700ºC. The main phase present in the samples, as detected by X-ray diffraction and Raman spectroscopy, was CaCu3Ti4O12. Scanning electron microscopy analysis showed that mesoporous structures, with thicknesses between 200-400nm, were developed as a result of the processing conditions. The films were tested regarding their sensibility towards oxygen and nitrogen at atmospheric pressure using working temperatures from 200 to 290ºC. The samples exhibited n-type conductivity, high sensitivity and short response times. These characteristics indicate that CCTO mesoporous structures obtained by sol-gel are suitable for application in gas sensing.