A Sequence of Phase Transformations and Phases in NiCoFeCrGa High Entropy Alloy.

The present investigation is directed to phase transitions in the equimolar NiCoFeCrGa high entropy alloy, which is a mixture of face-centered cubic (FCC) and body-centered cubic (BCC) crystalline phases. The microstructure of the samples was investigated by using scanning electron microscopy (SEM), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), transmission electron microscopy-based energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS), as well as X-ray diffraction (XRD) measurements. Based on the phases observed in different temperature ranges, a sequence of the phase transitions can be established, showing that in a realistic process, when freely cooling the sample with the furnace from high to room temperature, a microstructure having spinodal-like decomposition can also be expected.

Excitation energy trapping and dissipation by Ni-substituted bacteriochlorophyll a in reconstituted LH1 complexes from Rhodospirillum rubrum.

Bacteriochlorophyll a with Ni(2+) replacing the central Mg(2+) ion was used as an ultrafast excitation energy dissipation center in reconstituted bacterial LH1 complexes. B870, a carotenoid-less LH1 complex, and B880, an LH1 complex containing spheroidene, were obtained via reconstitution from the subunits isolated from chromatophores of Rhodospirillum rubrum . Ni-substituted bacteriochlorophyll a added to the reconstitution mixture partially substituted the native pigment in both forms of LH1.