Abstract
Cross sections of needle-like copper powders reduced from aqueous cupric sulphate solution by glucose were examined. They were exclusively pentagonal.
From these sections and their etch figures, a multiply twinned decahedron structure was suggested.
We demonstrated that the growth of the needle-crystals could be explained on the basis of twinaccelerated growth mechanism and further discussed the growing mechanism of the decahedrons larger than that might be expected from the thermodynamical speculation.
Some observations in favor of these explanations were given.
