An understanding of lattice strain, defects and disorder in nuclear graphite

Abstract

In this study, microstructural parameters, such as lattice dimension, micro-strain and dislocation density, of different neutron-irradiated graphite grades have been evaluated using the diffraction profiles of X-ray diffraction (XRD) and the scattering profiles of Raman spectroscopy. Using Gen-IV candidate graphite samples (grade PCEA, GrafTech), subjected to neutron irradiation at 900°C to 6.6 and 10.2 dpa, and graphite samples of similar grain size and microstructure taken from the core of the British Experimental Pile Zero reactor, which have been irradiated at 100-120 °C to 1.60 dpa, an investigation on the effect of irradiation dose and temperature on the aforementioned microstructural parameters is

Raman Study of Strain Relaxation from Grain Boundaries in Epitaxial Graphene Grown by Chemical Vapor Deposition on SiC

“…However, XRD is unsuitable for probing few-layer graphene films grown on SiC substrate because it needs constructive interference of x-rays reflected from a set of parallel atomic planes. Krishna et al [18] have done a comparative study of the microstructural information extracted from the peaks of both Raman and XRD spectroscopy, and found that both techniques produced agreeable results for the graphite lattice strain and crystallite size, which proves the validity of deducing both strain and crystallite size from Raman spectra. So, Raman is used to analyze both strain and grain size in this paper.…”

“…Both the strain and grain size in materials can be probed by XRD and Raman spectroscopy [16,17,18]. However, XRD is unsuitable for probing few-layer graphene films grown on SiC substrate because it needs constructive interference of x-rays reflected from a set of parallel atomic planes.…”

Carbon Nanofibers Encapsulated Nickel‐Molybdenum Nanoparticles as Hydrogen Evolution Catalysts for Aqueous Zn−CO2 System

“…It is noteworthy that the exposed graphite edges in NiMo/CNF provide much abundant carbon edge defects which can be catalytic active sites during electrochemical reactions . Furthermore, amorphous phase carbon and lattice defect are also observed in the carbon fiber (green spot in Figure f red square 2) due to low CVD temperature (400 °C) . On the other hand, the parallel growth of carbon is observed for the catalyst at 600 °C (Figure h) exhibits the existence of nanotubes instead of fibers .…”

Simple and Eco‐Friendly Fabrication of Electrode Materials and Their Performance in High‐Voltage Lithium‐Ion Batteries

“…The XRD pattern of the unleached and leached samples exhibits the typical peaks of a highly ordered graphite . Apart from the intense and symmetrical peak assignable to the plane (002), other planes of the structure corresponding to other crystallographic directions were clearly detected (Figure ).…”

“…As for the values of < e > ,t he changes are not significant, and the values are comparable to those described for commercial graphite evaluateda lso from XRD data using other calculation methods. [38,41] When these graphite particles are deformed either by grinding [41] or irradiation with neutrons, [38] clearly significant increases are observed;t hese increases can be greater than one order-of-magnitude. As for the valueso fL c calculated by Equation (1), the one obtained for the unleached graphite, aroundt hree times that calculated for the leached graphite and MCMB, deserves attention.T he values tend to equalize when the broadening of the three reflections (00l) is exclusively associated with the crystallite size, as in Equation (2).…”