Destruction of mesoscopic chemically modulated domains in single phase high entropy alloy via plastic deformation.

Chemically modulated mesoscopic domains in a fcc single phase CrMnFeCoNi equi-atomic high entropy alloy (HEA) are detected by small angle diffraction performed at a synchrotron radiation facility, whereas the mesoscopic domains cannot be detected by conventional X-ray diffraction and 2D mappings of energy dispersive X-ray spectroscopy by scanning electron microscopy and scanning transmission electron microscopy. The mesoscopic domains are deformed and shrieked, and finally destructed by plastic deformation, which is supported by the comprehensive observations/measurements, such as electrical resistivity, Vickers hardness, electron backscattering diffraction, and hard X-ray photoemission spectroscopy. The destruction of the mesoscopic domains causes the decrease in electrical resistivity via plastic deformation, so called K-effect, which is completely opposite to the normal trend of metals. We confirmed that the presence and the size of local chemical ordering or short-range order domains in the single phased HEA, and furthermore, Cr and Mn are related to form the domains.

High-resolution microscopy for biological specimens via cathodoluminescence of Eu- and Zn-doped Y2O3 nanophosphors.

High-resolution microscopy for biological specimens was performed using cathodoluminescence (CL) of Y(2)O(3):Eu, Zn nanophosphors, which have high CL intensity due to the incorporation of Zn. The intensity of Y(2)O(3):Eu nanophosphors at low acceleration voltage (3 kV) was increased by adding Zn. The CL intensity was high enough for imaging even with a phosphor size as small as about 30 nm. The results show the possibility of using CL microscopy for biological specimens at single-protein-scale resolution. CL imaging of HeLa cells containing laser-ablated Y(2)O(3):Eu, Zn nanophosphors achieved a spatial resolution of a few tens of nanometers. Y(2)O(3):Eu, Zn nanophosphors in HeLa cells were also imaged with 254 nm ultraviolet light excitation. The results suggest that correlative microscopy using CL, secondary electrons and fluorescence imaging could enable multi-scale investigation of molecular localization from the nanoscale to the microscale.