FIG. 2 is a scanning electron microscopic picture (a) and a transmission electron microscopic picture FIG. 2(a) is a scanning electron microscopic image (.times.2500), from which it is observed that carbon nanotubes (CNTs) are carried on the surface of catalyst coated Wollastonite in such state as being grown in parallel with one another in the approximately vertical direction to the surface. Further, the carbon nanotubes grew in symmetric directions while sandwiching the Wollastonite, and the whole construction was planar.
FIG. 2(b) is a transmission electron microscopic image (.times.300,000), from which it is understood that carbon nanotubes having a hollow construction are generated and carried on the surface of the Wollastonite. As the result of the observation with a scanning electron microscope, lengths of carbon nanotubes on the measured Wollastonite surface in the approximately vertical direction relative to the Wollastonite surface was from 5 to 25 .mu.m.
FIG. 10 is a scanning electron microscopic picture showing a granular carbon nanotube, Wollastonites carrying carbon nanotubes agglomerate to form a granule.
Methods for allowing the surface of the metal oxide particle to carry the carbon nanotube catalyst, include sputtering, vacuum evaporation, CVD, plating and the like, but, the simplest and most practical technique is a method of immersing the metal oxide particles in a solution of a catalyst metal compound. For example, Wollastonite is immersed in an aqueous solution of nickel nitrate and ammonium molybdate to carry a nickel and molybdenum catalyst.
The crystalline metal oxide particle used by Goto and Tani is a fibrous or tabular crystalline metal oxide particle, including, for example, particles of alkali earth metal silicate, alkali earth metal titanate, alkali titanate, and the like. Examples of fibrous or tabular alkali earth metal silicates include calcium silicate, magnesium silicate, aluminum magnesium silicate, strontium silicate, barium silicate, and the like. Examples of fibrous or tabular alkali earth metal titanates include magnesium titanate, calcium titanate, strontium titanate, barium titanate, and the like. .
