Abstract
Present-day multimedia strongly relies on re-writable phase-change optical memory. We have found that Ge2Sb2Te5 (GST), the material of choice in DVD-RAM, does not possess the conventional rock-salt structure as previously believed but that Ge and Sb atoms are displaced from the ideal rocksalt positions. Amorphization of both GeTe and GST results in a significant shortening of covalent bonds and a decrease in the mean-square relative displacement concomitant with a drastic change in short-range order. The order-disorder transition in GeTe and GST is primarily due to a flip of Ge atoms from octahedral positions into tetrahedral positions without rupture of strong covalent bonds. The driving force for the flip are strained Ge-Te bonds in the crystalline phase. It is this nature of the transformation that ensures large changes in reflectivity, fast disk performance and repeatable switching over millions of cycles.
Original language | English |
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Pages (from-to) | 1612-1615 |
Number of pages | 4 |
Journal | Journal of Non-Crystalline Solids |
Volume | 352 |
Issue number | 9-20 SPEC. ISS. |
DOIs | |
Publication status | Published - 2006 Jun 15 |
Externally published | Yes |
Keywords
- Chalcogenides
- Short-range order
- X-ray absorption
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry