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An innovative sol–gel process, using a mixture of Na(hfa)·tetraglyme and RE(hfa)3·diglyme (RE = Y, Yb, Tm) complexes, has been optimized to produce upconverting β-NaYF4:Yb3+/Tm3+ thin films. The X-ray diffraction (XRD) analysis confirms that the new sol–gel preparation route yields reproducibly and selectively the hexagonal Na(Y1.5Na0.5)F6 structure (β-NaYF4) without any impurity phases, since no peaks of the cubic NaYF4, YOF, Y2O3 or NaF phases were observed. This final goal has been achieved through an accurate optimization of the operative parameters such as the molar ratio of the precursor mixture, the aging time of the sol, the spin coating procedure and the annealing temperature. Field-emission scanning electron microscopy (FE-SEM) images indicate that the morphology of the surfaces, grain dimensions and thickness are strongly related to the processing parameters, with the hexagonal phase films having a very uniform morphology. Energy dispersive X-ray (EDX) analyses established the film composition in terms of dopant ions, which are responsible for the upconverting properties of the material. Luminescence measurements under laser excitation at 980 nm confirmed the promising upconversion properties of the β-NaYF4:Yb3+/Tm3+ films.

Calcium-doped praseodymium manganite films (Pr0.7Ca0.3MnO3, PCMO) were prepared by metal-organic chemical vapor deposition (MOCVD) on SrTiO3 (001) and SrTiO3 (110) single-crystal substrates. Structural characterization through X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) analyses confirmed the formation of epitaxial PCMO phase films. Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) characterization was used to confirm lateral and vertical composition and the purity of the deposited films. Magnetic measurements, obtained in zero-field-cooling (ZFC) and field-cooling (FC) modes, provided evidence of the presence of a ferromagnetic (FM) transition temperature, which was correlated to the transport properties of the film. The functional properties of the deposited films, combined with the structural and chemical characterization collected data, indicate that the MOCVD approach represents a suitable route for the growth of pure, good quality PCMO for the fabrication of novel spintronic devices.

Transparent MOCVD-grown NiO films have been functionalized with the luminescent (1,10-phenanthroline)tris(2-thenoyltrifluoroacetonato)europium(III) complex [Eu(TTA)3phen] by combining sputter activation with a solution synthetic route. To introduce the Eu complex only on selected regions, some areas of the NiO surface were activated by Ar+ ion sputtering and then functionalized with 3-phosphonopropionic acid (CPPA) followed by the anchoring of Eu(TTA)3phen through a ligand-exchange reaction between β-diketonato ligands and the carboxylic groups of CPPA. The functionalized material was characterized by X-ray photoelectron, UV/Vis and luminescence spectroscopy. XPS measurements indicated that CPPA prefunctionalization and, in turn, the Eu(TTA)3phen anchoring occurs only on the sputter-activated region, while no anchoring takes place on the unactivated surface. The optical properties of the Eu(TTA)3phen–NiO system were evaluated by UV/Vis and luminescence spectroscopy.

The physical properties of CaCu3Ti4O12 (CCTO) thin films grown by metal organic chemical vapor deposition on LaAlO3 substrates have been investigated. The structural, compositional, and optical characteristics have been evaluated, and all the collected data demonstrated that in the obtained (001) epitaxial CCTO thin films, a low defect density is present. The electrical behavior of the deposited thin films has been studied from both micro- and nanoscopic points of view and compared with the properties reported in the literature. The electrical measurements on large area capacitors indicated that in the investigated work frequency range (10(2)-10(6) Hz), the CCTO films possess dielectric constants close to the theoretically predicted "intrinsic" value and almost independent of the frequency. The nanoscopic dielectric investigation demonstrated that the deposited CCTO films possess n-type semiconducting nature and that a colossal extrinsic behavior can be locally achieved.