Directional Oxygen Functionalization by Defect in Different Metamorphic-Grade Coal-Derived Carbon Materials for Sodium Storage

As the limiting factor for an energy storage technique from lab-scale to industrial-scale,cost means not only the price of raw materials but also the simplicity of processing technics.In this work,the oxygen functionalized carbon materials were obtained from three representative different metamorphic-grade coals,that is,lignite,bitumite,anthracite.Oxygen functional groups like quinones,carboxylic anhydrides,and lactones are easier to form near defects according to the thermogravimetric-mass spectrometry measurements and density functional theory calculation.Considering the highest amount of defects and C=O contained functional groups,the low metamorphic-grade lignite derived carbon exhibits a reversible capacity of 259.7 mA h g^(-1)after 50 cycles at 0.03 A g^(-1),best among these micron sized coal-based carbons.The surface active sites contribute highly stable and majority of sodium storage capacity evidenced by in situ Raman spectra and cyclic voltammetry curves at different scan rates.The coal-based carbon materials in this work offer options for industrial applications of sodium-ion battery anode materials.

Ultrafast photoinduced strain in super-tetragonal PbTiO ferroelectric films

The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultrafast optical memories,sensors and actuators with strain engineering.The mechanism of screening of the depolarization field by photoinduced carriers is generally accepted for UPS in ferroelectrics,while the thermal component of the strain is usually diluted as the offset and has not been systematically confronted,leading to unnecessary confusion.Herein,both the positive and negative thermal expansion effects in composite ferroelectric epitaxial films are investigated by use of high-repetition-rate ultrafast X-ray diffraction,along with the piezoelectric and photovoltaic effects.The coupling of the positive/negative thermal effects and the piezoelectric/photovoltaic effects in ultrafast strain is evidenced and can be regulated.The opposite lattice responses due to different thermal effects of the samples with different axial ratios are observed.The maximum UPS is up to 0.24%,comparable to that of conventional ferroelectric.The interaction between the thermal and ferroelectric effects in the induced strain could promote the diversified applications with the coupling of light,heat and electricity.

Radiation damage of 1Cr18Ni9Ti and Zr-Ti-Al alloys due to energetic particle irradiation

The radiation damage of 1Cr18Ni9Ti stainless steel and the Zr-Ti-Al alloy by 200 keV Xe＋ ions bombardment at the fluence ranging from 1×1014 to 8×1015 ions/cm2 has been investigated by conventional transmission electron microscope, X-ray diffraction line profile analysis （XRDLPA） and nanoindentation. XRDLPA shows that the order of magnitude of dislocation density in both materials remains almost unchanged up to the highest irradiation dose. Selected-area electron diffraction combined with bright and dark field image indicates that 1Cr18Ni9Ti is more easily damaged than the Zr-Ti-Al alloy. With increasing the ions fluence, the radiation damage became more severe in 1Cr18Ni9Ti, accompanied with phase transition and partial amorphization. The nano-hardness was found to increase rapidly with increasing ion fluence till the dose of 1×1015 ions/cm2, and then gradually saturate with dose. The enhancement of hardness in irradiated materials is due to irradiation-induced defects acting as barriers to dislocation motion.