Chemistry Nexus
by WebElements: the periodic table on the web
Large Melting-Point Hysteresis of Ge Nanocrystals Embedded in SiO2
Abstract:
The melting behavior of Ge nanocrystals embedded within SiO2 is evaluated using in situ transmission electron microscopy. The observed melting-point hysteresis is large (±17%) and nearly symmetric about the bulk melting point. This hysteresis is modeled successfully using classical nucleation theory without the need to invoke epitaxy.1
References
WebElements December 15th, 2009
Posted In: Chemistry, Materials chemistry
Tags: Germanium
Spanish Post Office honours Mendeleev
Thi
s stamp commemorates the death of Mendeleev (February 1907), one of the lead figures responsible for the periodic table. Absolutely excellent choice of colours if I might say so!
The stamp was sent to me by Prof Gabriel Pinto (Departamento de Ingeniería Química Industrial, ETSI Industriales, UPM, Madrid, Spain) and I quote from his web page: “This stamp was launched on february 2, 2007, by Correos (Spanish Post Office).
WebElements February 2nd, 2007
Posted In: Chemistry
Germanium nanocrystals melt 200°C higher in glass than in bulk
Scientists at the Lawrence Berkeley National Laboratory in California, USA, have discovered that nanocrystals of germanium embedded in silica glass don’t melt until the temperature rises almost 200 degrees Kelvin above the melting temperature of germanium in bulk.1 What’s even more surprising, these melted nanocrystals have to be cooled more than 200 K below the bulk melting point before they resolidify.
WebElements October 9th, 2006
Posted In: Chemistry, Materials chemistry
Tags: Germanium
Conjuring Crystals
This is interesting. NASA scientists are examining a seemingly magical way to produce high-quality crystals.
Perhaps a NASA laboratory is an unlikely setting for a magic show. Nevertheless, this is where Frank Szofran and colleagues are growing high-quality crystals using a method as amazing as any conjuring trick. By carefully cooling a molten germanium-silicon mixture inside a cylindrical container, they coax it into forming a single large and extraordinarily well-ordered crystal.
WebElements December 11th, 2001
Posted In: Chemistry