We present a bottom-up fabrication route based on the sputtering gas aggregation source that allows the generation of nanoparticles with controllable and tunable chemical composition while keeping the control of the cluster size. We demonstrate that the chemical composition of the particles can be monitored by the individual adjustment of the working parameters of the magnetrons inserted in a gas aggregation zone. Such control of the parameters leads to a fine control of the ion density of each target material and hence to the control of the chemical composition of the nanoparticles. In particular, we show through X-ray photoemission, atomic force microscopy, and high-resolution transmission electron microscopy that it is possible to generate bimetallic (AgAu) and trimetallic (AgAuPd) alloy nanoparticles with well-defined and tunable stoichiometries from three targets of pure Ag, Au, and Pd. The proposed route for the generation of nanoparticles opens new possibilities for the fabrication of nanoparticles using a physical method that, for some applications, could be complementary to the chemical methods.

A silver-hydroxyapatite nanocomposite has been obtained by a colloidal chemical route and subsequent reduction process in H2/Ar atmosphere at350∘C. This material has been characterized by TEM, XRD, and UV-Visible spectroscopy, showing the silver nanoparticles (∼65 nm) supported onto the HA particles (∼130 nm) surface without a high degree of agglomeration. The bactericidal effect against common Gram-positive and Gram-negative bacteria has been also investigated. The results indicated a high antimicrobial activity forStaphylococcus aureus, PneumococcusandEscherichia coli,so this material can be a promising antimicrobial biomaterial for implant and reconstructive surgery applications.

Tunable and durable lotus effect on laser-patterned stainless steel via a vacuum process in a very short time interval.

Ultrahydrophobic self cleaning surface is fabricated with nanosecond laser source on aluminium foil.

A new pressureless hydrothermal method for the preparation of yttrium disilicate is presented. The obtained amorphous precursor was calcined at different temperatures to form the Y-, R-, β-, and γ-phases of Y 2 Si 2 O 7 , which have been characterized by DTA, XRD, TEM, and 29 Si-MAS RMN and IR spectroscopy. It is shown that the proposed method allows the strictly controlled doping of yttrium disilicate using RE elements such as dysprosium (2.5 and 5 at. %). The luminescent properties, in terms of emission efficiency, of different polymorphs of Dy-doped Y 2 Si 2 O 7 have been investigated by fluorescence measurements at room temperature. The results indicate that the β-phase doped with 2.5 at.% has the maximum efficiency. It is important to note that the efficiency of this phase is approximately 40% of that measured for the commercial phosphor Eu-Y 2 O 3 .

No abstract

No abstract

No abstract