A group of researchers at the universities of Jyvaskyla (Finland) and Xiamen (China) have found a novel way to make functional macroscopic crystalline supplies out of nanometer-size 34-atom silver-gold intermetallic clusters.
The cluster materials have a highly anisotropic electrical conductivity, being a semiconductor in one route and an electrical insulator in different directions. Synthesis of the fabric and its electrical properties had been investigated in Xiamen, and the theoretical feature of the material was carried out in Jyvaskyla.
The steel clusters had been synthesized via wet chemistry, including gold and silver salts and ethynyladamantane molecules in a mixture of methanol and both chloroform or dichloromethane.
All syntheses produced the same 34-atom silver-gold clusters with an equivalent atomic structure, however surprisingly, the use of dichloromethane/methanol solvent initiated a polymerization response after cluster formation in resolution and growth of human-hair-thick single crystals consisting of aligned polymeric chains of the clusters.
The crystals behaved as a semiconducting material in the route of the polymer and as an electrical insulator in the cross directions. This behavior arises from metal-metal atomic bonding in the polymer route, while in the cross instructions, the metal clusters are remoted from each other by a layer of the ethynyladamantane.
Theoretical modeling of the cluster material by computer-intensive simulations using the density practical concept predicted that the fabric has an energy hole of 1.3 eV for digital excitations.
This was verified by measurements of optical absorption and electrical conductivity in a layout where single crystals we mounted as a part of a field-effect transistor, which showed a p-type semiconductor property of the fabric.
Electrical conductivity along the polymer route was about 1800-fold as compared to the cross directions.