materials chemistry

Pimp My Spin Coater

My research has recently involved the process of spin coating, and being in a nuclear chemistry group we of course don’t have a spin-coater lying around. So, I’ve been hiking up the hill to use the Somorjai group‘s spin-coater. This past week I decided I wanted my own spin-coater and so I set about making my own. The working model is shown below.

Spin-Coater in the Dark: Lights are turned off for more dramatic effect.

If you’re going to start making your own lab equipment you might as well trick out the new hardware. In that spirit, my spin coater has 3 light emitting diodes: a green one, a red one, and a blue one. I can vary the revolution per minute from ~500rpm to ~2500rpm by varying the voltage I supply to the spin coater. The sample is mounted in the center and is stuck to the spin coater by Velcro, this can be more easily seen in the next photo.

Spin Coater Close Up

As can also be seen in the photo, my spin coater is just a regular pc fan I bought at CompUSA this past Wednesday. I monitor the speed of the spin coater with a laser mounted above the spin-coater that shines through the fan’s blades and strikes one of our group’s alpha detectors. The nice thing about the alpha detector is that I don’t even have to supply any power to it. There is enough current generated, I presume by the photoelectric effect, to carry a signal to an oscilloscope which I can use to monitor the fan’s speed. A picture of the laser, which is my boss’s laser pointer he uses for talks, is seen in the next photo at the top of our group’s only non-radioactive chemistry hood.

Spin-Coater in the Hood

It took me 2 days to build my spin coater, Wednesday and Thursday, and one more day to make sure it calibrates properly, Friday. The total amount in extra costs was $20 for the spin-coater(pc fan) all the rest of the equipment we had lying around.

Now what other lab equipment could use some LEDs? Hmmm….

Note 1: Paper that first got me interested in using a pc fan: Spin-Coating of Polystyrene Thin Films as an Advanced Undergraduate Experiment

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Fun with Europium Oxide Films

The research group I work in has been interested in making me make Eu2O3 films for some time now. I can’t go into specifically why the group is interested in it or how we are making the films. But, the overarching goal is to be able to make a thin homogeneous layer of europium oxide and then potentially apply that knowledge to other +3 metals and maybe +4 (hint-hint) too. As with any Lone-Wolf project, there are always major bumps and ditches when you’re test driving a new method that the research group has no prior experience with. After attempting this new method several times I could only make very thin layers, layers so thin that I hesitate to call them layers. At any rate, I purposefully made one massively huge layer of Eu2O3 on my substrate to verify that the new method actually works and to examine what the surface looks like under extreme fatness. See image below

Europium Desert: Image is on the several millimeters range.

The sample shows a blistered desert like surface. A colleague who was passing by thought it was an aerial photo of Nevada at first glance. The sample is definitely not the homogeneous non-cracked surface I was aiming for, but this was an experiment at extremes after all.

Looking closer at the same sample, but now at the several 10s of micrometers scale, I came across very exotic and organic looking structures, like the one shown below. I’ve dubbed it my Europium Coral.

Although, my europium coral is the embodiment of everything I don’t want (I just want a thin homogeneous layer of Eu2O3), it is unexpected and surprising results like this which keeps science fun. Who would of known a layer of europium oxide would look so interesting?


By January 8, 2007 0 comments materials chemistry