Artículos SCI

Porous NaMgF3 ceramics have been fabricated by leaching a NaF-NaMgF3 eutectic in distilled water, producing NaMgF3 with 53% of connected porosity. The eutectic was fabricated using the Bridgman technique at growth rates of 8, 10 and 15 mm/h. The microstructure and composition of the resulting material has been studied by means of X-ray diffraction and SEM. Compression mechanical tests have been performed at different temperatures up to 750 degrees C, both in constant strain rate and constant stress loading. The microstructure consists of plate-like grains with cylindrical pores in approximately hexagonal packing. Pores are perpendicular in adjacent grains. The compressive strength is found to be rather independent of growth rate, in the range studied. Small differences can be explained using a minimum solid area (MSA) model and differences in the microstructure. In creep experiments, no steady-state regime was observed. Instead, the strain exhibited a series of accelerations that could be associated with damage propagation. 

A synthetic route to building photoconducting films of TiO2 nanoparticles that display bright structural color is presented. The color arises as a result of the periodic modulation of the refractive index, which is achieved by controlling the degree of porosity of each alternate layer through the particle size distribution of the precursor suspensions. The suspensions are cast in the shape of a film by spin-coating, which allows tailoring of the lattice parameter of the periodic multilayer, thus tuning the Bragg peak spectral position (i.e., its color) over the entire visible region. Photoelectrochemical measurements show that the Bragg mirrors are conductive and distort the photocurrent response as a result of the interplay between photon and electron transport.