(gramatical errors on page will be corrected before publication, I wanted to get thoughts down) An atom in some classical definitions is : the smallest particle of matter that still retains the properies of the larger "bulk" of that material. However, as we learn more and more about particles on the nanoscale (4-10 nm) we find that the properties can be ratically different. For example, gold on the macro scale has a melting point of 1064 C, however, in small clusters, ranging in size from 4 to 10 nm, golds melting point significanltly changes to around 700 C (depending on cluster size). In addition, we find that the familair glod luster changes to redish hues. These striking differences arise because of something called surface properties. It turns out that as aggregates of particles are made smaller and smaller, a higher percentage of particles end up on the surface. This effects the stability of the metal bonds and leads to not only a closer packing structure than seen in the "bulk" but it also effects the electrical and electronic properties as well. Esentailly the electron arrangment actually changes as a function of size and as we know from basic chemistry -- it is the electrons that define many of an elements properties.
Alloys
Why is this of such great interest around the world? It turns out that nanoparticle clusters have many possible applications for use as catalysts, especially in the development of fuel cells. However, one of the most problematic changes that occurs, aside form the "curiosties" mentioned above is that the electrical potential of the clusters dramatically changes. What this means is that as the particles get smaller they are more likely to react with oxygen and convertfrom Ag to Ag +2 immediatly upon exposure to oxygen.
Why is this a problem?
Silver ions are soluable! That means that the nanoclusters you so carefully formed will disolve in a shorter time span than it took you to make them!
Enter the alloy.
Just as with alloys of metals on the bulk level tend to cause a blending of favorable properties, the blending of metals at the nanoscale may help to stabalize otherwise very unstable particles.
Our role
Our role, two other teachers (on a seperate grant) and myself will be experimenting with the concentrations of the ragents that make the alloy possible. To date the group, prior to my arrival has already formed aggragates of copper and silver independently. What we will be doing is varying the concentrations of the reagents and observing specrographic data to predict our results. These results can then be confirmed and the structure of the alloys can be analysed using x-ray defraction and electron microscopy.
Misbehaving clusters
(gramatical errors on page will be corrected before publication, I wanted to get thoughts down)An atom in some classical definitions is : the smallest particle of matter that still retains the properies of the larger "bulk" of that material. However, as we learn more and more about particles on the nanoscale (4-10 nm) we find that the properties can be ratically different. For example, gold on the macro scale has a melting point of 1064 C, however, in small clusters, ranging in size from 4 to 10 nm, golds melting point significanltly changes to around 700 C (depending on cluster size). In addition, we find that the familair glod luster changes to redish hues. These striking differences arise because of something called surface properties. It turns out that as aggregates of particles are made smaller and smaller, a higher percentage of particles end up on the surface. This effects the stability of the metal bonds and leads to not only a closer packing structure than seen in the "bulk" but it also effects the electrical and electronic properties as well. Esentailly the electron arrangment actually changes as a function of size and as we know from basic chemistry -- it is the electrons that define many of an elements properties.
Alloys
Why is this of such great interest around the world? It turns out that nanoparticle clusters have many possible applications for use as catalysts, especially in the development of fuel cells. However, one of the most problematic changes that occurs, aside form the "curiosties" mentioned above is that the electrical potential of the clusters dramatically changes. What this means is that as the particles get smaller they are more likely to react with oxygen and convertfrom Ag to Ag +2 immediatly upon exposure to oxygen.Why is this a problem?
Silver ions are soluable! That means that the nanoclusters you so carefully formed will disolve in a shorter time span than it took you to make them!
Enter the alloy.
Just as with alloys of metals on the bulk level tend to cause a blending of favorable properties, the blending of metals at the nanoscale may help to stabalize otherwise very unstable particles.
Our role
Our role, two other teachers (on a seperate grant) and myself will be experimenting with the concentrations of the ragents that make the alloy possible. To date the group, prior to my arrival has already formed aggragates of copper and silver independently. What we will be doing is varying the concentrations of the reagents and observing specrographic data to predict our results. These results can then be confirmed and the structure of the alloys can be analysed using x-ray defraction and electron microscopy.