This work describes the effect of the laser power and the exposure time on a sample of octahedron‐shaped nanocrystals of cobalt(II) oxide using Raman spectroscopy. Above a certain value of the laser power and exposure time, CoO rock salt sample evolves clearly to the oxidized Co3O4 normal spinel material because of the energy transfer and consequent local heating induced by the applied laser. The analysis of this thermodynamic CoO–Co3O4 crossover in octahedron‐shaped nanocrystals by means of the Raman spectroscopy has been performed. Copyright © 2017 John Wiley & Sons, Ltd.

Raman spectroscopy is a very valuable and fast-performance tool to gain insight first into the different iron oxide phases present in nanoparticles, to correlate then the magnetic properties with potential bio-related applications.

The origin of dielectric anomalies and magnetodielectric response of La2MnCoO6 has been investigated by means of ultra-high resolution synchrotron x-ray powder diffraction, neutron powder diffraction, resistivity, magnetization and dielectric measurements. The study has been performed on two different bulk samples presenting different degrees of Mn/Co order: 95 and 74%. Beside the well-known influence on magnetic properties, our results show that the main effect of disorder lies on the electrical resistivity. Bond distances clearly show Mn4+/Co2+ valence states in the well-ordered sample, while for the disordered one this picture still holds. AC resistivity data show dielectric anomalies and a small magnetodielectric effect, but impedance complex plane analyses prove that these phenomena appear at the frequency–temperature region where extrinsic effects dominate the dielectric response.

The combination of low electrical resistance and high optical transparency in a single material is very uncommon. Developing these systems is a scientific challenge and a technological need, to replace ITO in flexible electronic components and other highly demanding applications. Here we report a facile method to prepare single layers of densely aligned ultrathin Au-nanowires, homogeneous over cm(2) areas. The as-deposited films show an electrical/optical performance competitive with ITO and graphene-based electrodes. Moreover, the Au-films show a good stability under ambient conditions, and the large aspect ratio of the ultrathin nanowires makes them perfect for deposition in flexible substrates.

We are reporting the dielectric response of La 1.5 Sr 0.5 NiO 4 , a system that presents a charge-ordered state above room temperature and a rearrangement of its charge-order pattern in the temperature region 160-200 K. A careful analysis of the role of the electric contacts used, sample thickness and grain size on the experimental data allows us to determine that this material exhibits high values of intrinsic dielectric constant.The variation of the dielectric constant with temperature shows a maximum in the region of the rearrangement of the charge-order pattern, which constitutes an evidence of the link between both phenomena.