This paper reports an optimized, simple, fast and inexpensive method for hydroxyapatite (HA) nanoparticle synthesis. Through a multivariate statistical analysis using a factorial design with 23 resolution, an empirical model was developed which allows control of the shape and size of the HA nanoparticles. This model was used to synthesize HA nanoparticles with sizes between 8 and 600 nm, formed by oriented attachment growth mechanism. The structure was confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, which also showed that HA nanoparticles had well-defined nanorod forms and narrow size distributions. It was observed that the model is statistically significant and the main parameter for the growth of crystals in the hydrothermal process was temperature.

The production of high performance metal matrix composites depends on a proper design of the surface of the reinforcing phase, ensuring a good contact with a metal phase. In the present work, two Ag decorating procedures to modify the surface of multi-walled carbon nanotubes (MWCNT) were evaluated for further production of aluminum matrix composites. The procedures consisted in a two steps route based on acid oxidation of carbon nanotubes (CNT) followed by suspension in an Ag ion solution; and a single step route, based on the effect of n-dimethylformamide (DMF) as an activation agent of CNT surface, in presence of Ag ions. Transmission and scanning-transmission electron microscopy, Raman and Fourier-transformed infrared spectroscopy were employed in order to characterize the results. The two steps route resulted in Ag nano-particles homogeneously deposited over the CNT surface. The mechanism for the deposition is based on carboxyl and probably hydroxyl functional groups formed in the first step, acting as nucleation sites for Ag precipitation in the second step. The single step route resulted in the formation of sub-micrometric Ag particles heterogeneously mixed to CNT bundles.

We report a study of a new chemical synthetic route of polystyrene sulphonate (PSS) films doped with neodymium ion (Nd+3) from a neodymium nitrate solution. The UV-Vis-NIR spectrum presents an intense characteristic electronic transition at 800 nm and the infrared spectrum presents low definition bands as a result of Nd3+ coordination with PSS molecule. Additionally, the spectrum of Nd-PSS film presents the same line shape profile of Nd3+ salt in aqueous solution. Selective luminescence spectroscopy measures shows that the incorporation of neodymium ion introduces a red shift bands and a better line shape definition in UV luminescence compared to PSS film, decreasing the interaction between PSS aromatic groups. The near-infrared emission was observed in the large spectrum region from 600 to 800 nm; it is associated with the Nd3+ complex of PSS monomer.

In this work we describe the processing of poly(styrene sulphonate) films (PSS) doped with neodymium (Nd). Optical density measurements in the UV-Vis-NIR region show the typical bands observed for neodymium chloride (NdCl3) in solution. In the case of films, the intensity ratio between the peaks at 800 nm (4I9/2 -> 4F5/2 + ²H7/2) and 580 nm (4I9/2 -> 4G5/2 + ²G7/2) is equal to 0.83. Infrared spectra present an enhancement in the absorption region of aromatic rings. Site selective luminescence spectroscopy shows that the incorporation of Nd introduces a hipsochromic shift and a line shape definition in UV luminescence compared to PSS film, decreasing the interaction between aromatic groups. In addition, the film exhibits an intense radiative transition at 1061 nm (4F3/2->4I11/2), comparable to the one present in crystalline materials doped with Nd.