The ${\mathrm{Ti}}^{3+}$ center, based on a regular Ti site perturbed by an oxygen vacancy $\left({\mathrm{V}}_{\mathrm{O}}\right)$ , is identified by electron spin resonance (ESR) in textured $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_3$ films. The center shows tetragonal symmetry along cubic ⟨100⟩ axes with $g$ -factors: $g_{\Vert }=1.997$ , $g_{\perp }=1.904$ . The spectrum of this defect disappeared after the film annealing at $700°\mathrm{C}$ in an ${\mathrm{O}}_2$ atmosphere. We describe the observed spectrum as ${\mathrm{Ti}}^{3+}–{\mathrm{V}}_{\mathrm{O}}$ couple defects or $F^{+}$ center, which have never been observed in bulk $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_3$ . ESR is thus a unique tool to identify oxygen-vacancy-related defects, which have a large effect on the performance of ferroelectric films.

International audienceA comparison of crystallinity, microstructure, surface morphology and electrical conductivity is proposed for the deposition of copper films, using supercritical fluid chemical deposition (SFCD) and RF magnetron sputtering techniques. Both preparation methods yield nanocrystalline Cu films (< 100 nm) but SFCD gives access to a higher crystallinity for the same AlN substrate temperature during the deposit. Based on the film characteristics, a comparison of the evolution of electrical properties is done for RF magnetron sputtered copper films and SFCD ones with H2 as reducing agent. Uniform strain values are significantly reduced when SFCD technique is used and crystallinity is highly increased leading to lower resistivity values for a same crystallite size. This study demonstrates the viability of the SFCD technique to produce high quality nanostructured copper thin films with low resistivity values

Relaxors are very interesting materials but most of the time they are restricted to perovskite materials and thus their flexibility is limited. We have previously shown that tetragonal tungsten bronze (TTB) niobate Ba(2)PrFeNb(4)O(15) was a relaxor below 170 K and that Ba(2)NdFeNb(4)O(15) displays a ferroelectric behavior with a T(C) = 323 K. On scanning the whole solid solution Ba(2)Pr(x)Nd(1-x)FeNb(4)O(15) (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1), we demonstrate here a continuous crossover between these end member behaviors with a coexistence of ferroelectricity and relaxor in the intermediate range. This tunability is ascribed to the peculiar structure of the TTB networks which is more open than the classical perovskites. This allows for the coexistence of long range and short range orders and thus opens up the range of relaxor materials.