Recent engine testing on separate neutral and basic zinc dirhiophosphates (ZnDTPs) showed a drfference in valve train wear performance, with the neutral ZnDTP giving statistically better wear inhibition in Sequence VE rests. Since the literature was lacking on the oxidatiotl inhibition performance of the separate neutral and basic salts, we systematically examined the relative antioxidatlcy of several neutral and basic ZnDTP salts in various formulations. The results were dependent on the type of base oil and formulation used, and the presence of other additives. NMR Spectroscopy, coupled with Oxidator Bench Test studies, were used to reach these conclusions.

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The synthesis of zinc oxide nanoparticles, confined in a matrix of silicon dioxide from pure zinc and silicon targets, on a p-type silicon substrate was carried out. The technique of reactive cathodic erosion assisted by radio frequency without heat treatment after the deposit of the materials was used. The morphological, chemical, physical and electrical characterization of the structures obtained was carried out. It was possible to obtain a layer of SiO2 with roughness in the range of nanometers, on silicon substrates, controlling the partial pressure of oxygen during the process of cathodic erosion. The basins, typical of the roughness of the material obtained, served to house the metallic Zn, promoting its nucleation and its partial oxidation in a space reduced to the scale of nanometers. Subsequently, the complete oxidation of Zn and its confinement was achieved by depositing another layer of SiO2, obtaining samples with the structure: the p-type silicon substrate, a thin-roughness film of silicon oxide, n-type zinc oxide nanoparticles and finally a second layer of silicon oxide which completed the matrix; SiO2/n-ZnONP/SiO2/p-Sisustrate. First, the surface morphology of the samples is analyzed by atomic force, scanning and transmission microscopy, X-ray diffraction, and UV-visible light spectroscopy. The silicon dioxide composition of the first deposited layer is demonstrated by infrared spectroscopy. The presence and distribution of Zn particles were obtained through spectroscopy by scattered X-ray energies and by secondary ion mass spectroscopy. Subsequently, the presence of the stoichiometric ZnO compound is confirmed by X-ray photoelectric electron spectroscopy. The presence of ZnO particles with size <10 nm with hexagonal crystalline structure is evidenced by transmission electron microscopy. Finally, the rectifying behavior, typical of a p-n junction, and its electrical response to light by means of current-voltage, measurements in lighting and dark regime is demonstrated. The variation of its electrical characteristics to the stimulus of different wavelengths is evidenced by the spectral response technique.

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