Standardization

The results of an international comparison of the measurement of graphene, led by NPL, have been released. The work was conducted through the Versailles Project on Advanced Materials and Standards (VAMAS) and in collaboration with institutes from around the world.

The international interlaboratory comparison (ILC) outlined improvements that reduce measurement uncertainty, in some cases by a factor of 15, and which will be the basis for a new international standard which is currently under development within ISO/IEC for Raman spectroscopy. This will aim to become a verified source of data and ultimately provide more accurate and precise measurement standards for the global graphene industry.

Researchers from RWTH Aachen University and the Graphene Flagship Standardization Committee have pushed through a new IEC standard for assessing the strain uniformity of single-layer graphene using Raman spectroscopy.

Research has shown that the electrical and the structural quality of graphene are intimately connected, and that nanoscale lattice deformations caused by surface corrugations limit the mobility of electrons in graphene. Therefore, controlling the flatness of a graphene sheet is fundamental for the fabrication of high-quality graphene layers for electronic devices and the possibility of measuring this parameter with a simple and fast method is a major technological advantage. Furthermore, the new standard for detecting graphene flatness, pioneered by the Graphene Flagship and published by the International Electrotechnical Commission (IEC), could expedite the manufacture and implementation of single-layer graphene.

A research collaboration between The University of Adelaide in Australia and the National Physical Laboratory has led to the development of a validated analytical tool, thermogravimetric analysis (TGA), for the characterization and quality control of FLG and non-graphene impurities in powder form. TGA is typically used to assess and characterize the thermal properties and impurities of minerals, polymers, and carbon materials. However, its was found to have potential for use as a characterization tool for regulating the quality of graphene materials.

Now, this affordable, simple and reliable method of analysis could be used to improve the quality control measures used in the graphene industry.

The National Physical Laboratory (NPL), in collaboration with international partners, have developed an ISO/IEC standard, ISO/TS 21356-1:2021, for measuring the structural properties of graphene, typically sold as powders or in a liquid dispersion. The ISO/IEC standard helps the supply chain to better define graphene materials (and distinguish them from other materials) and is based on methods developed with The University of Manchester in the NPL Good Practice Guide 145.

Over the last few years, graphene has started to move from the laboratory into real-world products such as cars and smartphones. However, there is still a barrier affecting the rate of its commercialization, namely, understanding the true properties of the material. There is not just one type of material, but many, each with different properties that need matching to the many different applications where graphene can provide an improvement.

Monash University scientists have created an innovative method to help industry identify high quality graphene cheaper, faster and more accurately than current methods. The researchers used the data set of an optical microscope to develop a machine-learning algorithm that can characterize graphene properties and quality, without bias, within 14 minutes.

Framework for quantitative analysis. Image from Advanced Science

This technology could be a game changer for hundreds of graphene or graphene oxide manufacturers globally. It will help them boost the quality and reliability of their graphene supply without need for time-consuming procedures.

Recent research by NPL, Oxford Instruments, Chalmers University and Graphensic has enabled the quantum Hall effect to be realized at both lower magnetic fields and higher temperatures, whilst still retaining part per billion accuracies.

The long-term collaboration between NPL, Chalmers University of Technology and Graphensic has resulted in a big advance in graphene samples. Epitaxial graphene (epigraphene) has been grown on silicon carbide and has better performance at higher temperatures and lower magnetic field than was previously possible. In practical terms, it has also removed the difficult process of fine-tuning the carrier density and means the ‘table-top’ system can be warmed up and cooled back down and the plateau stays where it is set with no user intervention.

The International Organization for Standardization (ISO) has published standard ISO/TR 19733:2019, Nanotechnologies — Matrix of properties and measurement techniques for graphene and related two-dimensional (2D) materials.

ISO states that since graphene was discovered in 2004, it has become one of the most attractive materials in application research and device industry due to its supreme material properties and it is expected that applications of graphene could replace many of the current device development technology in flexible touch panel, organic light emitting diode (OLED), solar cell, supercapacitor, and electromagnetic shielding.

Researchers from the National University of Singapore (NUS) have set out to tackle the issue of a lack of graphene production standards, which leads to many cases of poor quality graphene from suppliers. The team developed a systematic and reliable method for establishing the quality of graphene samples from around the world. They were able to achieve this by using a wide range of analytical techniques and tested samples from many suppliers.

Upon analyzing samples from over 60 different providers from the Americas, Asia, and Europe, the NUS team discovered that the majority contained less than 10% of what can be considered graphene flakes. The bulk of the samples was graphite powder that was not exfoliated properly.

Graphene-Info has teamed up with world renowned laboratories to offer a unique graphene metrology service that provides characterization and analysis on graphene materials.

Dozens of companies are producing various types of graphene materials, which causes much diversification and confusion. Our metrology service offers graphene producers the chance to obtain valuable test results and post-testing analysis and interpretation, that assist in proving viability and quality of production. In addition, displaying critical data to customers like the material characteristics and potential applications is key to successful marketing and sales activities.

BSI, the UK-based standards body and global certification company, has published a new guide to the properties of graphene flakes, PAS 1201. The guide provides an explanation of the physical and chemical properties of graphene flakes, and advice on information manufacturers and suppliers of graphene should give to prospective users.

Dan Palmer, Head of Manufacturing at BSI, says: PAS 1201 sets out the information that any manufacturer or interested party needs to understand about graphene before introducing this material to the manufacturing process. Standardizing the information that is made available about properties of graphene flakes is important in order for the commercial opportunities of graphene in the UK to be realized.