Simulation der Nanostrukturbildung in Alkali-dotierten Fullerenschichten

This work presents theoretical background for the investigation of nanostructure formation in alkali-metal doped fullerene layers. A number of computational methods are used to describe structural transformation in the fullerene layer. They include tight-binding molecular dynamics, empirical molecular dynamics, Monte-Carlo calculations as well as other methods. The doped fullerene layers show the highest superconducting critical temperature among organic superconductors. A new electrochemical method of synthesis of potassium and rubidium fullerides has been recently developed by Professor Dunsch and coworkers in the department of electrochemistry and conductive polymers at IFW Dresden. The process of electrochemical doping is accompanied by several side effects, and one of them is nanostructure formation at the surface of the fullerene layer. In the present work an explanation is given for the nanostructure formation observed recently by scanning tunnel microscopy. The corresponding model is based on the concept of spontaneous phase separation that has been realized by kinetic Monte Carlo calculations. These calculations predict instability of initially homogeneous alkali-doped fullerene layers. Due to the significant gap in the Madelung energy formation of an alkali-poor and an alkali-reach phase is expected. The results of the Monte Carlo simulations point out that the particle size of the corresponding phases remains in the nanometer range. Interpretation of experimental data for metal deposition on fullerene substrates can be easily given in the framework of the phase separation concept as well. Metal clusters of the size order 50 to 100 nm emerge in course of electrochemical copper deposition on alkali-doped fullerene layers. The electrically conductive paths through the insulating fullerene layer are probably responsible for the inhomogeneous copper deposition under electrochemical conditions. A novel computer program has been developed in course of this work, which is designed as a distributed application. It can be used for diverse conventional and kinetic Monte Carlo calculations.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Technische Universität Dresden

Year

2004

Author dc:creator

• Touzik, Andrei

Contributors dc:contributor

• Wetzig, K.
• Seifert, G.
• Schmickler, W.

• Alkalimetall-Fulleriden
• C60
• Fullerenen
• Kalium-Fullerid
• Kohlenstoff-Nanostrukturen
• Molekulardynamik
• Monte-Carlo
• Phasenentmischung
• Rubidium-Fullerid
• kinetische Monte-Carlo-Simulationen
• Carbon nanostructures
• alkali-metall fullerides
• fullerens
• kinetic Monte-Carlo
• molecular dynamics
• phase separation
• potassium fulleride
• rubidium fulleride