The use of gaseous species has been proposed in the literature to counteract the three-dimensional growth tendency of noble metals on dielectric substrates and favor an earlier percolation without compromising electrical properties. This "surfactant" effect is rationalized herein in the case of O 2 presence during magnetron sputtering deposition of Ag films on SiO 2 . In situ and real-time techniques (X-ray photoemission, film resistivity, UV−visible optical spectroscopy) and ex situ characterizations (X-ray diffraction and transmission electron microscopy) were combined to scrutinize the impact of O 2 addition in the gas flow (%O 2 ), revealing three regimes of evolution of film resistivity, morphology, structure, and chemical composition. At low oxygen flow conditions (%O 2 < 4), the observed drastic decrease of the percolation threshold is assigned to a combination of (i) a change in nanoparticle density, wetting, and crystallographic texture and (ii) a delayed coalescence effect. The driving force is ascribed to the presence of specific adsorbed oxygen moieties, the nature of which starts evolving at intermediate oxygen flow conditions (10 ≤ %O 2 < 20). At high oxygen flow (20 ≤ %O 2 < 40), the found detrimental impact on film resistivity is assigned to an actual oxidation in the form of a Ag 2 O-like poorly crystallized compound. For all %O 2 , a composition gradient is observed across the film thickness, with a more metallic Ag at the substrate interface. A correlation between percolation and the nature of the detected O moieties is observed. In parallel to an oxygen spillover mechanism, this gradient can be explained by the competition between different surface processes occurring before percolation, namely, aggregation, metal oxidation, and substrate reactivity. Such findings pave the way to a rational use of O 2 as a modifier for Ag growth.

This study is part of a research project on pineapple fiber characterization for developing composite materials and their application to product design. It was conceived by the Bionics and Design Student Research Group, and one of its research areas is the classification and application of properties of the so-called agricultural waste to develop applications for industrial products. Pineapple waste, composed of the leaves of this plant, is called rastrojo (stubble) in Spanish, and it was selected due to its high production volume and environmental impact, which is progressive in plantations. An important aspect in this study is the current lack of information about the thermal properties of pineapple fiber, which is contradictory as several types of natural fibers are used as thermal insulators. This fact was a motivation to conduct this research and identify those properties. For this study, a pineapple plant was characterized. Subsequently, different tests and experiments were conducted, and the most appropriate methods were adopted. Thermal gravimetric analysis and differential scanning calorimetry were identified as the best methods for calculating degradation values, specific heat and thermal life.