Strukturelle und kinetische Aspekte der kombinatorischen Materialsynthese am Beispiel der Phasenwechselmedien
type: CreativeWork
description: Nowadays different competing techniques for reversible storage of huge amounts of data are used. One approach that has found extensive application is phase change recording, whereby data are encoded by using amorphous or crystalline states. Consequently the reading, writing and erasure of information is based on an optical approach whereby laser light is used to induce the corresponding reflectivity levels. In order to satisfy the rising demand for the design of new and superior phase change materials, an absolute experimentally Trial-and-Error-Method has been employed in the past. Efforts have been undertaken in this work to steer away from the trial and error approach by pursuing two systematic approaches to the design of phase change materials: On the one hand, the density functional theory has been utilized to predict the energetically favored crystal structure of an alloy. The influence of the crystal structure on the kinetics of the phase transformation and of the coordination number and the band gap on the optical properties was discussed. To this end, AgInTe and AgSbTe alloys were theoretically investigated for this purpose. The predicted structure for the Indium-based alloy is the chalcopyrite structure and it was also confirmed experimentally. The low coordination number of 4 leads to a weak overlap of the energy bands resulting in an energy gap of 1 eV. Compared to other phase change materials, the low change of density and therefore of the local atomic configuration leads to a weak optical contrast, which disqualifies this material for phase change recording applications. The exchange of the Indium fraction by an Antimony component led to a preference of the rocksalt structure, which was theoretically predicted and experimentally verified. The coordination number of 6 leads to a pronounced change of the optical properties, which accompanies the transformation from the amorphous to the crystalline state. These suitable optical properties of AgSbTe rendere…
abstract: Nowadays different competing techniques for reversible storage of huge amounts of data are used. One approach that has found extensive application is phase change recording, whereby data are encoded by using amorphous or crystalline states. Consequently the reading, writing and erasure of information is based on an optical approach whereby laser light is used to induce the corresponding reflectivity levels. In order to satisfy the rising demand for the design of new and superior phase change materials, an absolute experimentally Trial-and-Error-Method has been employed in the past. Efforts have been undertaken in this work to steer away from the trial and error approach by pursuing two systematic approaches to the design of phase change materials: On the one hand, the density functional theory has been utilized to predict the energetically favored crystal structure of an alloy. The influence of the crystal structure on the kinetics of the phase transformation and of the coordination number and the band gap on the optical properties was discussed. To this end, AgInTe and AgSbTe alloys were theoretically investigated for this purpose. The predicted structure for the Indium-based alloy is the chalcopyrite structure and it was also confirmed experimentally. The low coordination number of 4 leads to a weak overlap of the energy bands resulting in an energy gap of 1 eV. Compared to other phase change materials, the low change of density and therefore of the local atomic configuration leads to a weak optical contrast, which disqualifies this material for phase change recording applications. The exchange of the Indium fraction by an Antimony component led to a preference of the rocksalt structure, which was theoretically predicted and experimentally verified. The coordination number of 6 leads to a pronounced change of the optical properties, which accompanies the transformation from the amorphous to the crystalline state. These suitable optical properties of AgSbTe rendere…
author: Detemple, Ralf
language: ger
keywords: info:eu-repo/classification/ddc/530, Optischer Speicher, Strukturelle Phasenumwandlung, Antimontelluride, Dotierung, Sekundärneutralteilchen-Massenspektrometrie, Physik, Massendatenspeicher, kombinatorische Materialsynthese, Phasenwechselmedien, Dichtefunktionaltheorie
date published: 2003
date modified: 2026-07-30T19:42:39Z
provider: RWTH Aachen University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Publikationsserver der RWTH Aachen University