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In this paper, a thorough study is dedicated to the manipulating of nanostructured zirconia thin films prepared by a sol-gel process with the focus on the wetting properties. It is observed that by engineering the amount of cetyltrimethylammonium bromide [[N(CH3)3] Br] (CTAB) and polyethylene glycol (PEG) in zirconium chloride precursor solution, the novel agar-like morphology with random orientation can be grown. Different morphologies are observed by changing the amount of PEG in the solution. All the prepared samples in this method show tetragonal phase after annealing at 500 °C for 1 h. The crystallite sizes have a direct correlation with the ratio of lattice parameters. The optical band gap is estimated by Kubelka-Munk method. Modified ZrO2 thin films at an optimum ratio of PEG to CTAB annealed at 500 °C and present water contact angle lower than 3° (without UV illumination) which indicates their superhydrophilic properties. The analytical results of SEM images of samples annealed at 500 °C are also reported. Spreading and wicking of liquid through the nanochannels which are formed in the vacant spaces between nanorods lead to superior wetting property. Annealing temperature also strongly affects the wettability of agar-like zirconia thin films. Agar-like ZrO2 thin films are obtained with superhydrophilic behavior by annealing at 500 °C. Similar agar-like morphology is also observed with hydrophobic character by annealing at 200 °C. The introduced preparation method in this paper provides an easy route to fabricate superhydrophilic agar-like ZrO2 thin films without further processing. [ABSTRACT FROM AUTHOR]

Yttria stabilized zirconia (7YSZ) solution precursor has been successfully used in the deposition of high durability thermal barrier coatings. In this paper, the thermal and crystallization behaviors of 7YSZ precursor were investigated by TG-DTA, FTIR and XRD. The results show that the precursor decomposition and crystallization temperatures greatly depend on heating rate e. g. 74°C for the crystallization temperature when tripping the heating rate. With a 10 °C/min heating rate, the weight loss due to precursor pyrolysis occurs predominantly at temperatures below 500 °C. A small weight loss due to the oxidation of residual carbon is detected from 800 °C to 950 °C. The complete crystallization of the tetragonal phase was determined to be around 500 °C by DTA and XRD analyses with a 10 °C/min heating rate. The crystallization kinetics and the activation energy of amorphous 7YSZ precursor were investigated by variable heating rate DTA. The calculated activation energy is 66.2 kJ/mol. The Avrami parameter value was determined to be 2.68, which indicates that crystallization nucleation and growth is diffusion-controlled. The crystalline phase of 7YSZ coatings deposited by the Solution Precursor Plasma Spray process was identified by XRD and Raman spectrum. The average YSZ grain size in the SPPS coating was determined to be 61 nm. [ABSTRACT FROM AUTHOR]

Multilayer thin film of Gd-doped ceria and zirconia have been grown by sputter-deposition on α-Al2O3 (0001) substrates. The films were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The Gd-doped ceria and zirconia layers had the fluorite structure and are highly textured such that the (111) plane of the films parallel to the (0001) plane of the α-Al2O3. The epitaxial relationship can be written as $$ ( 1 1 1)_{{{\text{ZrO}}_{ 2} /{\text{CeO}}_{ 2} }} //(000 1)_{{{\text{Al}}_{2} {\text{O}}_{3} }} $$ and $$ [ 1 1{-}2]_{{{\text{ZrO}}_{2} /{\text{CeO}}_{2} }} //[ - 2 1 10]_{{{\text{Al}}_{2} {\text{O}}_{3} }} $$, respectively. The absence of Ce3+ features in the XPS spectra indicates that the Gd-doped ceria films are completely oxidized. The ionic conductivity of this structure shows great improvement as compared with that of the bulk crystalline material. This research provides insight on designing of material for low temperature electrolyte applications. [ABSTRACT FROM AUTHOR]

The pulsed laser deposition technique was applied to deposit nitrogen-doped yttria stabilized zirconia (YSZ) thin films. The working parameters were varied in order to achieve a maximal nitrogen content. The films were characterized by SIMS, XPS, X-ray diffraction and optical spectroscopy. The surface topography was studied by AFM and HRSEM. The influence of the deposition parameters on the film properties is discussed. [ABSTRACT FROM AUTHOR]

ZrO2 and SiC ceramic thin films and their bilayer have been successfully prepared by a newly developed electrostatic atomization technique. This technique can generate fine spray of ceramic suspensions in a micrometer sized range with a narrow size distribution which is crucial for preparation of uniform thin films of these ceramic materials. Compared to some other thin film deposition techniques, such as Chemical vapour deposition (CVD), physical vapour deposition (PVD) and plasma spray (PS) etc. the thin film deposition process using electrostatic atomization is not only cheap but also controllable. The prepared ZrO2 and SiC thin films were investigated using scanning electron microscopy (SEM) and energy dispersion analysis (EDA) techniques. These thin films were observed to be homogenous with a particle size less than 10 μm. The ZrO2-SiC bilayer was found to have an abrupt interface, implying that the deposition process is controllable and also that functionally graded ceramic/ceramic materials can be prepared in this way if the thickness of each layer is accurately controlled. [ABSTRACT FROM AUTHOR]

The chemical stability of diffusion couples and coarse grain powder mixtures of calcium substituted lanthanum manganite and cubic calcia stabilized zirconia have been studied. The aim was to investigate the chemical stability of these materials as a model system for respectively the cathode and the electrolyte in solid oxide fuel cells. With increasing amount of Ca in lanthanum manganite, the major secondary phase was shifted from La2Zr2O7 to CaZrO3, and the thickness of the reaction layers of secondary phases was increasing with increasing heat treatment time. Precipitation of La2O3 had taken place in the perovskite containing low amounts of Ca (0 and 20 mol %). The transport mechanisms of the cations were strongly dependent on the interface geometry. La0.7Ca0.3MnO3 was observed to give the most stable interface to zirconia both in air and in reducing atmosphere (pO ∼ 10−6 atm). A-site deficiency of LaMnO3 was also observed to increase the stability. However, we conclude that a thin film of an electrode material consisting of lanthanum manganite on a zirconia substrate is unstable, regardless of A-site deficiency, because the solubility limit of Mn in the zirconia is not reached. From the experimental data, a reaction mechanism has been proposed, based on observations of relative diffusion rates. [ABSTRACT FROM AUTHOR]