Morphological and structural control of nanostructured < 100 > oriented CeO2 films grown on random metallic substrates

CeO2 (cubic fluorite) thin films have been deposited on no-rolled Hastelloy C276 substrates by metal-organic chemical vapour deposition (MOCVD) from the Ce(hfa)(3)center dot diglyme [Hhfa 5 1,1,1,5,5,5- hexafluoro- 2,4- pentanedione; diglyme = (CH3O(CH2CH2O)(2)CH3)]precursor. The X-ray patterns of all samples grown in the 350-55 degrees C temperature range point to the formation of < 100 > oriented CeO2 films, while at higher deposition temperatures (650-850 degrees C) random CeO2 films are formed. XRD data indicate that 450 degrees C is the best deposition temperature. Detailed studies of the influence of all deposition parameters ( precursor vaporization temperature, O-2 and Ar gas flows, deposition temperature and time) on the CeO2 film growth have been carried out. There is evidence that the deposition process occurs in a mass transport regime. A suitable rationale for the observed textural changes vs. temperature has been proposed and the present columnar grain morphology, depending upon deposition temperatures, has been related to the zone model proposed by Mochvan and Demchishin for physical vapour deposition processes.