Polymer Graphite Pencil Lead as a Cheap Alternative for Classic Conductive SPM Probes

Abstract

This paper presents polymer graphite (PG) as a novel material for the scanning tunneling microscopy (STM) probe. Conductive PG is a relatively modern nanocomposite material used for micro-pencil refills containing a polymer-based binding agent and graphite flakes. Its high conductivity and immunity against surface contamination, with a low price, make it seem like a highly suitable material for electrode manufacturing in general. For the tip production, three methods were developed and are further described in the paper. For the production, three commercially available polymer graphite rods were used. Each has been discussed in terms of performance within the tunneling microscope and within other potential applications.

Field Emission Properties of Polymer Graphite Tips Prepared by Membrane Electrochemical Etching

“…The graphite pencil rods have generally two main constituents: graphite itself and various clay minerals or rocks, which are finely ground (small amounts of wax or polymers are also present to serve as a binder) [ 11 , 14 ]. It was reported that polymer graphite contains usually from 30% up to 80% of sp 3 hybridized carbon which may shift its properties more toward those of diamond-like carbon (DLC) structures [ 11 ]. The macroscopic hardness of polymer graphite rod is determined by the graphite–clay ratio.…”

“…Graphite-based materials such as graphene are also capable of replacing conventional capacitors as its electrical characteristics 10–100 times exceed those of the currently used material—silicon (100 times thinner, 20 times more powerful, significantly superior electrical conductivity, etc.). Graphite-related carbon allotropes are also often incorporated as a source of field emission current in vacuum [ 8 , 9 , 10 ] or as a source of tunneling current operating both in vacuum and in atmospheric conditions [ 11 ].…”

“…Polymer graphite (PG) is a relatively young nanocomposite material that was invented mainly for micro-pencil refills containing a polymer-based binding agent and graphite flakes [ 11 ]. The electrochemical method that is used by us to obtain a sharp tip is one of the three previously used methods enabling to form the PG rods [ 11 ]; however, for the PG, the method has not been studied in more detail yet. The PG has high conductivity and immunity against surface contamination, with a low price, which make it seem a highly suitable material for electrode manufacture in general [ 11 , 12 , 13 , 14 ].…”

“…The electrochemical method that is used by us to obtain a sharp tip is one of the three previously used methods enabling to form the PG rods [ 11 ]; however, for the PG, the method has not been studied in more detail yet. The PG has high conductivity and immunity against surface contamination, with a low price, which make it seem a highly suitable material for electrode manufacture in general [ 11 , 12 , 13 , 14 ]. Such pointed graphite rods may find various applications in analytical methods; for example, they can be used as a source of free electrons [ 15 ] or they can operate with a tunneling current in Scanning Probe Microscopy (SPM) conductive modes [ 11 ].…”

“…The PG has high conductivity and immunity against surface contamination, with a low price, which make it seem a highly suitable material for electrode manufacture in general [ 11 , 12 , 13 , 14 ]. Such pointed graphite rods may find various applications in analytical methods; for example, they can be used as a source of free electrons [ 15 ] or they can operate with a tunneling current in Scanning Probe Microscopy (SPM) conductive modes [ 11 ]. To conclude, it should be mentioned that graphite structures attract the attention of researchers from all over the world.…”