Standards Development

Scope

This part of IEC/TS 62607 establishes a standardized method to determine the key control characteristic defectiveness of graphene and related materials in powder form by Raman spectroscopy.

In particular, this standard can be applied in graphene materials in stages 1 or 2 of defects and not only in materials with low density of defects, and graphene materials showing vacancy, edge or sp3 defects.

Purpose

Determination of defectiveness is a key parameter for the industrial application of the graphene materials in powder form due to its influence in the electrical and thermal properties, sensing properties and its interaction with a matrix material, amongst other properties.

The amount and nature of defects strongly depends on the production method and has a strong influence on the properties of graphene samples.

Different types of defects are present in graphene materials such as edge defects, grain boundaries, vacancy defects, implanted atoms and heteroatoms, and sp3 defects.

IEC 62607-06-11 described the method to study density of defects by RAMAN spectroscopy, however, it is focused on films, and in particular materials with a low defect density with FWHM < 30 cm-1. That limits the methods applicability for powder materials which usually have a higher defect density.

IEC CD 62607-6-14 described the method of the determination of defect level based on Raman spectroscopy for graphene powders. This method specifies the evaluation of the defect level in graphene powder by the intensity ratio of D+D’ and 2D bands (ID+D’/I2D). This standard reports that D+D’ band is only relevant with defects in graphene layer, but not with edges and boundary defects. However, in some types of graphene materials, in particular those with ‘stage 2’ defects, there are no more well defined second-order peaks and 2D or DD´ bands are not observed. Therefore, the method of the determination of defect level specify in IEC CD 62607-6-14 cannot be used.