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In this work, aluminum doped La2O3 thin films deposited by the spray pyrolysis technique, are investigated by many characterization techniques. First, XRD spectra reveal the presence of two phases. A dominant cubic phase is obtained for pure La2O3 with (220) preferential orientation. The second hexagonal phase with (004) orientation is present in all doped samples. It is found that Al doping induces a perovskite crystalline structure identified as lanthanum aluminate (LaAlO3). Second, FTIR spectra include the main peaks of La‐O bonds related to La2O3 structure. Photoluminescence (PL) shows a good enhancement by Al doping related to LaAlO3 nanoparticles. Finally, the surface wettability measurements corroborate the hydrophobic character of all doped samples. [ABSTRACT FROM AUTHOR]

Titanium oxides and their alloys are widely used in medical applications because of their biocompatibility. However, they are characterized by their low resistance to corrosion. The HaP + TiO2 nanocomposites' coating was applied in different experiments, especially on a Ti-6Al-4V substrate with the spray pyrolysis process to deal with such weakness. The TiO2 content effects on the surface morphology and the phase composition were investigated using a scanning electron microscopy, X-ray microanalysis (SEM-EDXS) and X-ray diffraction (XRD). The mechanical properties were determined with nanoindentation. The potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and simulated body fluid (SBF) solution environment tests were carried out to investigate the corrosion resistance of HaP + TiO2/Ti6Al4V systems. The experimental findings revealed that sprayed thin films possessed uniform morphology. The coatings' nanoindentations proved that the HaP + 20% TiO2 coating hardness (252.77 MPa) and the elastic modulus (52.48 GPa) overtopped those of the pure hydroxyapatite coatings. The corrosion test demonstrated that the corrosion current density of about 36.1 µA cm−2 and the corrosion potential of the order of −392.7 mV of HaP + 20% TiO2 was lower compared to the pure HaP coating. [ABSTRACT FROM AUTHOR]

This work aims to study the structural, optical, and photocatalytic properties of ZrO2 nanotubes (NTs) that have been synthesized using the electrochemical anodization method. The structural and morphological characteristics of unannealed and annealed (400 °C, 500 °C, and 700 °C) ZrO2 NTs were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Details of the structural and morphological results are depicted to clarify the effect of annealing temperature on the NTs. Furthermore, the reflectivity and photoluminescence of ZrO2 NTs were found to depend on the annealing temperature. The resulting bandgap values were 3.1 eV for samples annealed at 400 °C and 3.4 eV for samples annealed at 550 and 700 °C. Thus, amorphous and annealed ZrO2 NTs were tested in terms of their photocatalytic degradation of Black Amido (BA) dye. Samples annealed at 400 °C exhibited 85.4% BA degradation within 270 min compared to 77.5% for samples annealed at 550 °C and 70.2% for samples annealed at 700 °C. The anodized ZrO2 NTs that were annealed at 400 °C showed the coexistence of tetragonal and monoclinic crystalline phases and exhibited the fastest photocatalytic performance against the BA dye. This photocatalytic behavior was correlated to the crystalline phase transformation and the structural defects seen in anodized ZrO2. [ABSTRACT FROM AUTHOR]

In this contribution, we report reliable ab initio quantum mechanical simulations of a variety of physical properties concerning yttrium sesquioxide (Y2O3) in different arrangements from the bulk, the monolayer (h‐Y2O3), to the (n,0) single‐walled nanotubes in the range from n = 6 to 32, for geometry optimization and vibrational properties. Structural parameters, phonon wavenumbers, infrared (IR) and Raman intensities, and elastic constants are computed via density functional theory (DFT/B3LYP) where the trend towards the (h‐Y2O3) monolayer for large nanotube radius is discussed. We firstly report combined experimental and computational studies on the structural and vibrational properties of the bulk Y2O3. Then, IR and Raman spectra of all arrangements are simulated via the coupled perturbed Hartree–Fock and Kohn–Sham (CPHF/KS) computational schemes. For the (n,0) Y2O3 nanotube family, two sets of IR active phonon modes in the (200–400 cm−1) and (600–900 cm−1) ranges are determined. Both of them tend smoothly with different slope, towards the optical vibrational modes of the h‐Y2O3 single layer. Three sets of active phonon bands are obtained in their Raman spectrum. The first one, in the 0–100 cm−1 range contains two phonon modes, their vibration wavenumbers tend to zero at very large tube radius and are found to be connected to the elastic constants C11 and C66 of the h‐Y2O3 monolayer as the 1D → 2D transition is approached. The second one, in 200–400 cm−1 range tends to the optical mode E′ (ν = 308 cm−1) of the monolayer. The third set, in the 600–900 cm−1 range contains two active modes, their intensities tend to zero in the limit of large nanotube without change in their vibration wavenumbers. [ABSTRACT FROM AUTHOR]