In this work, iron oxide nanoparticles produced using the laser ablation technique were studied in order to determine the characteristics of these nanoparticles as a function of the laser energy for the possible application in magnetic hyperthermia. Nanoparticles were obtained by varying the power of the laser considering values of 90, 173, 279 and 370 mJ. The morphology of these nanoparticles was determined using the dynamic light scattering (DLS) and scattering transmission electron microscopy (STEM) techniques, confirming that the size of the particles was in the order of nanometers. A great influence of the laser power on the particle size was also observed, caused by the competition between the energy and the temperature. The composition was determined by X-ray diffraction and Raman spectroscopy, showing the presence of magnetite, maghemite and hematite. The hyperthermia measurements showed that the temperature rise of the iron oxide nanoparticles was not greatly influenced by the energy change, the heating capacity of magnetic NPs is quantified by the specific absorption rate (SAR), that tends to decrease with increasing energy, which indicates a dependence of these values on the nanoparticles concentration.

A study of VN/TiN multilayers grown by direct current magnetron sputtering is presented. The systems are produced by maintaining a constant thickness of 500 nm and using three, four, or five bilayers. The coatings are initially characterized using X-ray diffraction. We observe the formation of TiN and VN phases and obtain values of the texture and stress developed during their growth. The chemical composition of the coatings is analyzed using X-ray photoelectron spectroscopy. A morphological analysis is carried out using atomic force microscopy, with a roughness of 1.57 nm obtained. The coefficient of friction is determined using the ball-on-disc method and is $0.45 for all samples. It is found that the wear rate is improved with decreasing bilayers as a consequence of the higher interfacial density (number of interfaces per total thickness). Finally, the wear mechanisms are identified as abrasive and adhesive.