Anatase TiO₂ nanoparticles doped with Al or Fe have been synthesized via a modified Pechini method which allows us to reach high control in size and composition. Microstructural analysis confirms the good crystallinity of the doped anatase nanoparticles with average sizes around 5 nm and dopant cationic concentrations up to 30%. The anatase to rutile transition (ART) has been thermally driven and analyzed as a function of the doping. Thermo-diffraction measurements indicate that the phase transition can be either promoted or inhibited by Fe or Al doping, respectively. The influence of Al and Fe doping on the phase transition has been discussed by means of Raman spectroscopy, photoluminescence and X-ray photoelectron spectroscopy, with special attention paid to the role played by Ti³⁺ at the surface. The anatase phase has been stabilized up to temperatures above 900 °C by appropriate Al doping.

Nickel oxide (NiO) is one of the very few p ‐type semiconducting oxides, the study of which is gaining increasing attention in recent years due to its potential applicability in many emerging fields of technological research. Actually, a growing number of scientific works focus on NiO‐based electrochromic devices, high‐frequency spintronics, fuel cell electrodes, supercapacitors, photocatalyst, chemical/gas sensors, or magnetic devices, among others. However, less has been done so far in the development of NiO‐based optical devices, a field in which this versatile transition metal oxide still lags in performance despite its potential applicability. This review could contribute with novelty and new forefront insights on NiO micro and nanostructures with promising applicability in optical and optoelectronic devices. As some examples, NiO lighting devices, optical microresonators, waveguides, optical limiters, and neuromorphic applications are reviewed and analyzed in this work. These emerging functionalities, together with some other recent developments based on NiO micro and nanostructures, can open a new field of research based on this p ‐type material which still remains scarcely explored from an optical perspective, and would pave the way to future research and scientific advances.

Cr doped SnO₂ microtubes have been fabricated by a thermal evaporation–deposition method.

In this work, layered hybrid composites formed by tin oxide (SnO) nanoparticles synthesized by hydrolysis and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) have been analyzed. Prior to the composite study, both SnO and PEDOT:PSS counterparts were characterized by diverse techniques, such as X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), photoluminescence (PL), atomic force microscopy (AFM), optical absorption and Hall effect measurements. Special attention was given to the study of the stability of the polymer under laser illumination, as well as the analysis of the SnO to SnO₂ oxidation assisted by laser irradiation, for which different laser sources and neutral filters were employed. Synergetic effects were observed in the hybrid composite, as the addition of SnO nanoparticles improves the stability and electrical conductivity of the polymer, while the polymeric matrix in which the nanoparticles are embedded hinders formation of SnO₂. Finally, the Si passivation behavior of the hybrid composites was studied.