14 DAY TRIAL // One would be tempted to think that if we use a technology, then we must understand how it works. This is sadly not true all of the time, as evidenced by the fact that we have been using DVDs for years, without knowing how exactly the storage mechanism functions. A new study finally clears that up.
Putting your favorite music, movies and photos on DVD has become standard practice, and everyone knows that the bits of 1s and 0s are inscribed in a special layer at the bottom of a plastic disc.
But the physical basis of this storage mechanism have never been fully understood in detail, researchers say, and this has always bugged some. Such a team published more details on how data are stored on DVDs in the January 9 issue of the esteemed scientific journal Nature Materials.
The Jülich, Finland-based study team cooperated closely with colleagues from Japan, in order to understand how DVDs work, and learn how to construct better, more advanced storage materials.
Experts say that this investigation kicked off like any other, from studying the polycrystalline alloy that makes up the disc layer on which information is stored. Every bit of data is less than 100 nanometers in diameter, physicists add.
There are multiple chemical elements in this particular alloy, which allows the material to take either an amorphous (disordered) or crystalline (ordered) form. The transition between the two can be triggered via the use of a laser pulse, and lasts only nanoseconds.
Germanium (Ge), antimony (Sb) and tellurium (Te), in a combination called GST, are the most commonly-used alloy chemicals for DVD-RAMs and Blu-ray Discs.
AIST alloys – silver (Ag), indium (In), antimony (Sb) and tellurium (Te) – are used to create DVD-RW.
“Both alloy families contain antimony and tellurium and appear to have much in common, but the phase change mechanisms are quite different,” says Forschungszentrum Jülich expert Dr. Robert Jones.
Using the facility's JUGENE supercomputer, the international team analyzed experimental data obtained by most advanced X-ray source in the world, the Japanese synchrotron Spring-8.
Through this approach, the group was able to determine the structures of both phases for the first time ever. With the newly-obtained data, they also developed a model that explains the rapid phase change.
In the future, the team plans to use this knowledge to create better alloys, that would be able to store even more data than Blu-ray discs, Science Blog reports.