Lecture #18, Friday, May 8th

Today I outlined the overview of the REEL research projects. There are two main themes present in the project. #1 In REEL 4 we saw that cations with an ns² cation or a Ag⁺ can effectively reduce the band gap. We want to investigate what will happen when we form a solid solution between end members containing these cations. More importantly, we want to see how the band gap changes as we change the4 composition of x. Does the band gap consistently change as we go from x = 0.1 to x = 0.9, does it lie very close to end member A, or does it lie close to end member B? There might be rare cases where the band gap of a solid solution falls outside the band gap of the end members. This could be a consequence of forming a two phase mixture or a compound with impurities, or it could be because there is a rare case. What you will have to do is prove to us if you have a two phase mixture or a solid solution based upon your XRD pattern.

We also want to look at various effects of putting a transition metal with valence d electrons in a solid solution. Do the absorption bands resulting from the d to d transitions stay at the exact same absorbance, or do they move to the left or to the right?

Next, we started with the Thermodynamics unit and will continue with that later next week. I hope everyone has a great mother's day weekend. Don't forget to tell your mom how much you care about her. You never know when your last opportunity to do that will be.

See you in class on Monday, Dr. Fus