Electrostatic spray deposition of NiO/CGO films

• Published in: Journal of physics. D, Applied physics Vol. 40; no. 11; pp. 3448 - 3455
• Main Authors: Hwang, Bing-Hwai, Chang, Chin-Liang, Hsu, Ching-Shiung, Fu, Cheng-Yun
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.06.2007; Institute of Physics
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Spray coating techniques; Nickel oxides; Scanning electron microscopy; Wetting; Spray coatings; XRD; Electrostatic wave; Precipitation; Composite materials; Composite coating; Gadolinium additions; Droplets; Microstructure; Cerium oxides
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/40/11/028

Deposition parameters were varied systematically to obtain NiO/Gd-doped CeO2 composite films using the electrostatic spray deposition method. The microstructure and morphology of the obtained films were investigated using a scanning electron microscope and an x-ray diffractometer. The degree of wetting of aerosol droplets on substrates decreased in the order of silicon wafer > stainless steel > glass. For deposition on silicon wafers, a continuous, flat layer was formed first due to excellent wetting of aerosol droplets on the substrate. Isolated particles were then nucleated and precipitated from the subsequent landing droplets and scattered on the bottom layer due to the very limited wetting of aerosol droplets on the flat oxide layer. Preferential landing of aerosol droplets on the isolated particles and subsequent precipitation and agglomeration of the fine particles finally resulted in a cauliflower morphology. Higher deposition temperature and lower flow rate of precursor solution resulted in drier droplets and hence diminished wetting and favoured particle precipitation, preferential landing of aerosol droplets and subsequent particle agglomeration. Increasing substrate roughness also favoured preferential landing of aerosol droplets and particle agglomeration. The composition of the deposited films was in fairly good agreement with that of the starting solution as revealed by the inductively coupled plasma mass spectrometer.