Carbon nanocone

Electron microscopy reveals that the opening angle (apex) of the cones is not arbitrary, but has preferred values of approximately 19°, 39°, 60°, 85° and 113°.

This method is often referred to as Kvaerner Carbon Black & Hydrogen Process (CBH) and it is relatively "emission-free", i.e., produces rather small amount of air pollutants.

Even if not optimized, it yields small amounts of carbon nanocones, which had been directly observed with an electron microscope already in 1994,[3] and their atomic structure was modeled theoretically the same year.

The graphene sheet is composed solely of carbon hexagons, which can not form a continuous cone cap.

Their values deviate from prediction by about 10% due to the limited measurement accuracy and slight variation of the cone thickness along its length.

High-resolution electron microscopy reveals that the ordered phase consists of nearly-parallel layers of graphene.

[1] The remarkable feature of the open carbon nanocones produced by the CBH process is their almost ideal shape, with straight walls and circular bases.

Another anomaly was a cone with the apex extended from a point to a line segment, as in the expanded coffee filter (flat form is shown in the picture).

SEM images of a carbon disk (top left image) and free-standing hollow carbon nanocones produced by pyrolysis of heavy oil in the Kvaerner Carbon Black & Hydrogen Process. Maximum diameter is about 1 micrometer. [ 1 ]
Atomic model of a cone with the 38.9° apex angle. [ 1 ]
Statistical distribution of the apex values measured over 1700 hollow nanocones. [ 6 ]
Image of a coffee filter illustrating one of the anomalous structures in the carbon nanocone growth.
Statistical distribution of the apex values measured over 554 cones grown on natural graphite. [ 7 ]
Sequential electron micrographs showing the process of capping a gold needle with a CBH carbon nanocone (top left) [ 9 ]