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Structural and Electrical Properties of Sol–Gel‐processed CdTiO 3 Powders and Films
Author(s) -
Montenero Angelo,
Canali Marco,
Gnappi Guglielmina,
Bersani Danilo,
Lottici Pier Paolo,
Nunziante Patrizia,
Traversa Enrico
Publication year - 1997
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/(sici)1099-0739(199702)11:2<137::aid-aoc560>3.0.co;2-v
Subject(s) - sol gel , thin film , raman spectroscopy , scanning electron microscope , chemistry , analytical chemistry (journal) , phase (matter) , perovskite (structure) , thermogravimetric analysis , orthorhombic crystal system , titanium dioxide , relative humidity , chemical engineering , mineralogy , materials science , crystallography , crystal structure , composite material , nanotechnology , optics , chromatography , physics , organic chemistry , engineering , thermodynamics
Cadmium titanate, CdTiO 3 , was prepared by the sol–gel technique in bulk and in thin film form. The thermal evolution of the gels and the phase changes were studied by thermo‐ gravimetric analysis (TGA), X‐ray diffractometry (XRD) and Raman and energy‐dispersive (EDS) spectroscopies. The morphology of the samples was observed using scanning electron microscopy (SEM). Gels heated to 800 °C gave rise to powders with only the ilmenite‐like phase. The orthorhombic perovskite phase is the only crystalline phase observed after a 4 h heat‐treatment at 1100 °C. With respect to the conventional preparation method by solid‐state reaction, by the sol–gel method it is possible to prepare the ilmenite phase at lower temperatures and the perovskite phase in a shorter time. Clear, homogeneous thin films were obtained by the dip‐coating method. The refraction index and the thickness of the films were measured using ellipsometry. The humidity‐sensitive electrical properties were measured for thin films deposited on alumina substrates with comb‐type gold electrodes, heated to 200 °C and 450 °C. The films heated to 200 °C, which still contained organics, showed a variation of the resistance of six orders of magnitude in the relative humidity (RH) range tested (4–87% RH). The films heated to 450 °C, made of ilmenite‐type CdTiO 3 , were nearly insensitive to RH. © 1997 by John Wiley & Sons, Ltd.