Electron microscopic and X-ray diffraction investigations of nanostructured thin films of ZnO
ZnO films prepared by sol-gel technique using zinc nitrate and zinc acetate as precursor material have been studied using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The results show the formation of zinc oxide phase. The nanostructure of the films was studied by transmission electron microscopy. Nano-structured fine grains of size ranging from 20-60 nm were observed with zinc nitrate precursor film. Individual grains show a sharp contrast with different facets and boundaries. Films prepared by zinc acetate precursor show ultra-fine nano-grains in the shape of dendrites as seen by the TEM. XRD shows a larger size of crystallites with the zinc acetate precursor. Crystal planes and lattice parameters calculated by both electron diffraction and X-ray diffraction are quite close and in agreement with the reported values in literature.
Characterization of thin films of ZnO prepared by sol-gel processes
Thin films of ZnO have been grown using sol-gel technique. The precursor materials for sol preparation include zinc acetate or zinc nitrate. Characterization was done using optical absorption, ellipsometry, X-ray diffraction, photoluminescence and scanning electron microscopy.
Measuring Sheet Resistances of Dielectrics Using Co‐Planar Hydrogel Electrochemical Cells with Practical Applications to Characterize the Protective Quality of Paints on Sculptures
Electrical properties of thin dielectric films at the solid-liquid phase boundary are an important performance characteristic of many devices, coatings and sensors. In this paper, co-polymeric hydrogels of polyacrylic acid co-sulfonic acid, swollen with a salt solution to act as the solid electrolyte, were used to assess interfaces using electrochemical impedance spectroscopy (EIS) in a co-planar geometry. Silane-modified glasses were characterized by the co-planar hydrogel EIS cell and found to be distinguishable based on their surface monolayer chemistry. EIS measurements were also made on primed and painted metal substrates, using both test panels and an outdoor sculpture, Tony Smith's Stinger. The panels were then exposed to accelerated and outdoor weathering and showed degradation on the surface paint layers, which was observable electrochemically using EIS and confirmed visually by SEM. Electrochemical spectral features were compared between data from a standard paint-test cell versus this co-planar hydrogel cell; both cell types were able to measure coating capacitance, providing useful information about the condition of the bulk coating. Yet, sheet resistance (Rs) was a spectral feature seen only by the co-planar hydrogel cell. Thus, it can be concluded that the use of such co-planar hydrogel cells can provide an earlier warning sign to coating degradation and such cells provide a new type of spectral information that is not assessable by the standard geometry.