Out-of-equilibrium dynamics driven by photoinduced charge transfer in CsCoFe Prussian blue analogue nanocrystals.

In this paper we study the out-of-equilibrium dynamics associated with photoinduced charge-transfer (CT) in cyanide-bridged Co-Fe Prussian blue analogue nanocrystals. In these coordination networks, the structural trapping of the photoinduced CT polaron involves local electronic and structural reorganizations. Femtosecond X-ray and optical absorption spectroscopies show that the local structural trapping process occurs on similar timescale for particles with 11 nm and 70 nm sizes. The local photoinduced spin transition, elongating the Co-N bonds and driving the CoIIIFeII → CoIIFeIII CT, activates coherent lattice torsion modes. The elastic deformation waves, launched by these bond elongations, drive macroscopic volume expansion and breathing of the particles. The timescale of this macroscopic deformation depends strongly on the size of the particle, which is more evidence of the multiscale nature of photoinduced phenomena in molecular materials.

Data on SiC-based bundle lifetime variability: The insufficiency of external phenomena affecting the flaw size.

A broad variability characterizes the lifetime of SiC-based bundles under static fatigue conditions at intermediate temperature and ambient air, challenging the accuracy of its prediction. The same is true, in a lower extend, with tensile properties, in apparent discrepancy with the bundle theory based on weakest link theory. The data presented here focus on lifetime scattering, evaluated on different fiber types (6 in total, Nicalon® or Tyranno®). It is hosted at http://dx.doi.org/10.17632/96xg3wmppf.1 and related to the research article "Static fatigue of SiC-based multifilament tows at intermediate temperature: the time to failure variability" (Mazerat et al., 2020) [1]. The insufficiency of classically invoked external and discrete bias (fiber sticking phenomenon for instance) was compared to a devoted Monte Carlo algorithm, attributing to each filament a strength (random) and a stress (homogeneous). Introduction of a stress inconsistency from tow to tow, experimentally observed through section variability, was revealed to overpass such biasing approach. This article can be referred to for the interpretation or prediction of CMC lifetime to guaranty long term performances over the broad offered application field.

Dataset on fractographic analysis of various SiC-based fibers.

This data article reports a systematic fractographic analysis of SiC-based filaments aiming at stress intensity factors assessment. A total of 11 fiber types (as-received or chlorinated Nicalon® and Tyranno® of all three generations) where therefore repeatedly tensile tested to generate the fracture surfaces. The tensile strengths were found to be independent to defect location (surface or internal). The well-known linear square root dependence of strength on mirror, mist or hackle outer radius was reaffirmed. These measurements reveal some residual tensile stresses on Nicalon® fibers, statement however questioned by the broad data scattering. Moreover, it is shown the surface etching treatment didn't affected (generating or releasing) such residual stress. A null y-intercept was consequently adopted to assess the characteristic stress intensity factors (KIC , mirror, mist or hackle constants). The toughness (KIC ) estimated this way ranges from 1.0 to 1.9 MPa m1/2 and shows a clear dependency to substrate composition: higher values were extracted on oxygen-free fibers. The Am /KIC ratio, estimated to equal 1.8 and independent to substrate type, is a key parameter that would assist further fractographic investigations.

Statistical data for the tensile properties and static fatigue of sic-based bundles.

Due to their high specific strength at elevated temperatures and resistance to oxidative environments, SiC-based fibers are of great interest for the reinforcement of ceramic matrix composites. They are however subjected to a slow crack growth (SCG) phenomenon causing their delayed failure under subcritical conditions. The testing of filaments, other than comprising handling difficulties, requires large sets of data (broadly dispersed), drawback alleviated by multifilament tow testing. The data available in the present paper correspond to a comprehensive mechanical characterization and static fatigue testing of various types of SiC-based fiber bundles. The initial non-linearity of load displacement curves were analyzed to reveal the tow structure originating from filament misalignment. Static fatigue tests were used to assess the lifetime prediction coefficients and its distribution parameters. These data may found interest for the interpretation of dispersion bundle testing can highlight under different solicitation mode. Such data are also prominent for the wealth of composite design and to guaranty long term performances over the broad application field offered.