X-ray absorption spectroscopy gives new insights into how DVD works

Scientists at North Carolina State University, USA recently published an interesting report on the significance of the anomalously high concentration of local Ge-Ge bonds in amorphous Ge₂Sb₂Te₅, which is commonly used in data storage technologies such as DVD, DVD-RAM etc. The ability to change phases from a crystalline to a non-crystalline state is what allows the DVD to take and hold data. While the basic properties of this alloy are well known, there are still a lot of unsolved problems: we do not know how the process works on a microscopic level. The paper indicates that the amorphous phase is an ideal network structure in which the average number of constraints per atom equals the network dimensionality. For more information, see the paper, ""Application of Bond Constrain Theory to the Switchable Optical Memory Material Ge₂Sb₂Te₅", D. A. Baker et al., Phys. Rev. Lett. 96, 255501 (2006).