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In this paper, we applied on the surface of the new Ti-20Nb-10Zr-5Ta alloy nano-crystalline hydroxyapatite (HA) coating by the method of the chemical deposition in a solution supersaturated with Ca2+ and [ABSTRACT FROM AUTHOR]

In this paper, we applied the potentiostatic anodisation method on the new Ti-20Nb-10Zr-5Ta alloy surface with the aim to increase its stability and bioactivity. The morphology (SEM) and composition (Raman, FT-IR) of the obtained anodisation nanolayer are studied. Also, electrochemical stability (by cyclic potentiodynamic polarisation and EIS), corrosion resistance (by linear polarisation), long-term behaviour (by monitoring of the open circuit potentials and corresponding open circuit potential gradients) and the characterisation of the layers deposited on the alloy surface after 1000 h in acid, neutral and alkaline Ringer and neutral Ringer-Brown solutions are presented. By potentiostatic anodisation, on the alloy surface was electrodeposited a continuous nanolayer containing TiO2 rutile type oxide. The anodised layer possesses better protective properties and at the same time better porosity, therefore a higher stability and bioactivity in comparison with the native passive film. After 1000 h in the testing solutions promoted the deposition of the brushite, phosphatotitanate and hydroxyapatite, precursors, respectively component of the human bone, namely this layer is bioactive. [ABSTRACT FROM AUTHOR]

A new ternary Ti-15Zr-5Nb alloy was elaborated with the aim to satisfy the most stringent requirements of a good implant material. The alloy has α + β bi-phase microstructure (by XRD and optical microscopy) and presents a proper combination between Young's modulus, elasticity and good ultimate tensile strength and 0.2% yield strength (from stress-strain tensile curve), indicating a good suitability as implant material. Electrochemical behaviour in artificial Carter-Brugirard saliva of different pH values (3.96, 7.84, and 9.11) and composition (un-doped and doped with 0.05 M NaF) that simulate the severe functional conditions in the oral cavity was evaluated. All electrochemical parameters of the new alloy revealed more favourable values than those of the CP Ti and Ti-6Al-4V ELI alloy, showing a more compact, resistant passive film formed on the new alloy surface. The corrosion rates and corresponding ion release rates for the new Ti-15Zr-5Nb alloy exhibited very low values (hundreds of times smaller) in comparison with similar commercial biomaterials. Electrochemical impedance spectra distinguished bi-layered passive film formed by inner, barrier layer and outer, porous layer. X-ray photoelectron spectra and scanning electron microscopy (SEM) observations proved that in time, protective compounds were deposited from saliva on the alloy surface, enhancing its corrosion resistance. [ABSTRACT FROM AUTHOR]

The paper describes a simple low-temperature synthesis route of preparing bismuth ferrite thin films through a wet chemical process, using nitrates of bismuth and iron and two chelating agents (citric acid and polyvinyl alcohol). The films were successively deposited on different type of substrates (silica glass, steel and sintered alumina) using the immersion technique. After specific annealing, in air, the samples were characterized by scanning electron microscopy (SEM), spectroellipsometry (SE), X-ray diffraction (XRD), X-ray photoelectron (XPS) and Raman spectroscopy. The influence of chelate agent and the nature of substrates on the mechanism formation of BiFeO3 is emphasized. [ABSTRACT FROM AUTHOR]

The crystallization of ZrSiO4 and its evolution with temperature from chemically homogeneous alumina-silica-zirconia powders prepared by sol-gel method from alcoxide mixtures was studied in the silica-rich region. A glass with the same composition was obtained by quenching in water from the melt. The gel-glasses evolution and microstructure were studied by means of XRD, IR and SEM/EDX, in the range of temperatures up to 1650oC. The materials consisted mainly of amorphous phase up to 1200oC, at which partial crystallization of cristobalite was observed. IR spectroscopy analysis showed zircon bands after thermal treatment at 1200oC. The crystallization of zircon and zirconia particles at 1550oC was confirmed by SEM/EDX analysis. At 1650oC the only stable crystalline phase observed after 40 h of thermal treatment was zircon.La cristalización de ZrSiO4 y su evolución con la temperatura se ha estudiado en la región rica en sílice, a partir de polvos amorfos y químicamente homogéneos de alumina-sílice-circona, preparados mediante método sol-gel usando mezclas de alcóxidos. Se obtuvo un vidrio con idéntica composición mediante enfriamiento rápido por inmersión en agua del material fundido. La evolución y la microestructura de los vidrios obtenidos se estudió mediante difracción de rayos X, infrarrojos, microscopía electrónica de barrido y análisis químico, en el rango de temperaturas hasta 1650oC. Los materiales están formados principalmente por fase amorfa hasta 1200oC, temperatura a la cual se observa la cristalización parcial de cristobalita. El análisis por espectroscopía de infrarrojos muestra bandas de circón en muestras tratadas térmicamente por encima de 1200oC. Las observaciones mediante microscopía electrónica confirman la cristalización de partículas de circón y circona a 1550oC. A 1650oC la cristobalita ha fundido y la única fase cristalina estable detectada mediante XRD tras 40 h a esta temperatura es circón.

Nanosized TiO2 layers containing polyethylene glycol (PEG) with 20,000 molecular weight were prepared by sol-gel method and deposited on three different substrates: microscope standard slides, Fluorine doped Tin Oxide (FTO) glass and Silicon, followed by thermal treatment at 450 °C. The effects of the substrate on the microstructural, morphological, chemical and optical properties of the films have been studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Atomic Force Microscopy (AFM), X-ray Photo-electron Spectroscopy (XPS) and Spectroscopic Ellipsometry (SE). The XRD showed that the film crystallization depends very much on the substrate used, thus the films deposited on glass are amorphous even after 1 h thermal treatment at 450 °C, while the films deposited on Silicon and FTO substrates are crystallized in anatase phase, in good agreement with the TEM analysis. The XPS analysis showed that a rather high carbon relative concentration in the TiO2 film (without PEG) exists; this suggests that an unavoidable carbon contamination occurs and is not related on the presence or absence of PEG. The thickness and surface roughness of the films are clearly dependent on the substrate type. The flat surfaces of glass and Si lead to the formation of thinner TiO2 films (around 30 nm thicknesses), while the FTO substrate surface leads to thicker film (thickness ~100 nm). The porosity of TiO2 films as found by SEM and TEM analyzes is dependent of substrate type; small pore sizes up to 20 nm are characteristic for the films deposited on glass, while larger pore sizes up to 200 nm are found for the films deposited on FTO substrate. Not least, the film transmissions in the visible region are also substrate dependent and the highest values (80%) were obtained for the films deposited on glass. [ABSTRACT FROM AUTHOR]

Fe3O4 nanoparticles were synthesized by a wet chemical method using Fe(III)/Fe(II) - hydrazine dihydrochloride systems. The structure, morphology, and magnetic properties of magnetite were examined by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), Mössbauer spectroscopy and superconducting quantum interference device (SQUID). Almost all the particles exhibit superparamagnetic like properties at room temperature. This behavior can be correlated with the size of the particles which ranged between 20-70 nm. [ABSTRACT FROM AUTHOR]

A new CoCrNbMoZr alloy, with Nb and Zr content is characterized from the point of view of surface features, corrosion resistance and biological performance in order to be proposed as dental restorative material. Its properties are discussed in comparison with commercial Heraenium CE alloy based on Co, Cr and Mo as well. The microstructure of both alloys was revealed by scanning electron microscopy (SEM). The composition and thickness of the alloy native passive films were identified by X-ray photoelectron spectroscopy (XPS). The surface characteristics were analyzed by atomic force microscopy (AFM) and contact angle techniques. The quantity of ions released from alloys in artificial saliva was evaluated with inductively coupled plasma-mass spectroscopy (ICP-MS) measurements. The electrochemical stability was studied in artificial Carter-Brugirard saliva, performing open circuit potentials, polarization resistances and corrosion currents and rates. The biological performance of the new alloy was tested in vitro in terms of human adipose stem cells (hASCs) morphology, viability and proliferation status. The new alloy is very resistant to the attack of the aggressive ions from the artificial saliva. The surface properties, the roughness and wettabiliy sustain the cell behavior. The comparison of the new alloy behavior with that of existing commercial CoCrMo alloy showed the superior properties of the new metallic biomaterial., (Copyright © 2015 Elsevier B.V. All rights reserved.)