73% spinel (MgAl 2 O 4 (ss)) and 27% MgO(ss). At 72 wt% Al 2 O 3 , there is a distinct compound (spinel) up to 1400 ° C and a nonstoichiometric solid solution or liquid above that T. At 50:50 wt% and 1900 ° C, what is the equilibrium concentration? Note there is a difference between mol% and wt% . 1) Identify T and phases 10% 65% 50%
What happens if we anneal to 460 ° C a Si device with Cu lines fabricated on top?
Upon cooling from above 802 ° C?
Imagine the interface composition is 50/50 wt%. What if we now heat up beyond 802 °C?
Si Cu Cu Cu Si Cu Cu Cu η ” Si Cu Cu Cu L and Si Si Cu η η ’ η ” Cu η η ’ η ” Cu η η ’ η ”
SiO 2 -Al 2 O 3 Adding alumina leads to mullite (ss). Mullite is 3Al 2 O 3 .2SiO 2 (60 mol % Al2O3 and is an important constituent in porcelain. Clays with <60 % Al 2 O 3 convert to mullite, or porcelainite ,
A Chalcogenide glass is a glass containing a sulphur, selenium or tellurium as a substantial constituent.
The crystalline and amorphous states of chalcogenide glass have dramatically different electrical resistivity values, and this forms the basis by which data is stored. The amorphous, high resistance state is used to represent a binary 0, and the crystalline, low resistance state represents a 1.
Chalcogenide is the same material utilized in re-writable optical media (such as CD-RW and DVD-RW). In those instances, the material's optical properties are manipulated, rather than its electrical resistivity, as chalcogenide's refractive index also changes with the state of the material.
Although PRAM has not yet reached the commercialization stage for consumer electronic devices, nearly all prototype devices make use of a chalcogenide alloy of germanium, antimony and tellurium (GeSbTe) called GST. It is heated to a high temperature (over 600°C), at which point the chalcogenide becomes a liquid. Once cooled, it is frozen into an amorphous glass-like state and its electrical resistance is high. By heating the chalcogenide to a temperature above its crystallization point, but below the melting point, it will transform into a crystalline state with a much lower resistance. This phase transition process can be completed in as quickly as five nanoseconds (modern DRAM cells have a switching time on the order of two ns).