Solid State Chemistry Final Project
This was a class project in Solid State Chemistry course: Synthesizing AlNi and AlNi3 intermetallic compounds.
Key Points
- Al and Ni have face-centered cubic (fcc) structures. Synthesized AlNi and AlNi(3) alloys have simple cubic (sc) structures, given powder X-ray diffraction (XRD) measurements, within 0.5% difference compared to literature values.
- Homogeneously powdered samples have low-noise XRD measurements, compared to heterogeneously powered samples.
Synthesizing AlNi Alloy
AlNi was synthesized on Monday, Nov. 23, 2015. Below is a video we filmed.
Solid Chemistry course was instructed by Professor George Lisensky at Beloit College, Wisconsin, U.S. The experiment followed the instructions in the paper "X-ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment" published in Journal of Chemical Education (2015), vol. 92, p. 1095–1097. Thanks to Thomas D. Varberg and Kacper Skakuj from Macalester College for designing the experiment.
Pressured AlNi pellet by hydraulic press at 6000 psi.
Heating the AlNi pellet using a Bunsen burner in a fumehood (Photo credit: G. Lisensky).
Due to the high temperature of the reaction (~4000° C?), the stainless steel screen was partially melted. A hole of the size of the AlNi pellet was created (Photo credit: G. Lisensky).
Final product AlNi alloy, probably with a little bit iron from the melted stainless steel screen that was supporting the pellet (Photo credit: G. Lisensky).
Professor George Lisensky is documenting the experiment.
Video: Exothermic Reaction of Synthesizing AlNi Alloy
Synthesizing AlNi(3) Alloy
Both AlNi(3) pellets (black cylinders) are strongly attracted to the magnet (white block). The magnetic force can support the weights of both alloy pellets.
AlNi(3) (1:3 ratio) pellet is glowing after less than 7 seconds being placed in a muffle furnace at 1100°C.
AlNi(3) (1:3 ratio) pellet after being baked at 1100°C in a muffle furnace for 10 minutes. The green finish is due to NiO (Varberg and Skakuj, 2015).
After being placed in the muffle furnace, both AlNi(3) alloy pellets (green cylinders) are significantly less magnetic than before. Even at close proximity between the synthesized alloys and the magnet (white block), the alloys are not attracted to the magnet, since the magnetic force attraction could not overcome friction. Door kys serve as a scale bar.
XRD Measurements, Calculations, and Conclusions
The X-ray Diffractometer used in this experiment: Rikaku Miniflex II.
All six samples were examined by XRD except for pure nickel.
- The first AlNi and second AlNi have the same composition. But the first AlNi sample was not homogeneous in size when the XRD measurement was taken. Scroll down to compare the difference in their XRD measurements.
- Two AlNi(3) samples have slightly different starting compositional ratios of Al and Ni. AlNi(3) (1:3 ratio) has a Al-to-Ni ratio of 1:3 in mole. AlNi(3) (1:2.5) has a Al-to-Ni ratio of 1:2.5 in mole. Suggested by the original designers of the experiment, The amount of Ni was scaled down in order to reduce the amount of unreacted Ni (Varberg and Skakuj, 2015).
Pure nickel powder.
Pure aluminum powder.
The first AlNi alloy is on the left and the second AlNi alloy on the right. Most of the prominent peaks match up. In the first AlNi alloy, the tremendous noise and intensity may be due to the inhomogeneous power. The second AlNi alloy power was much finer and homogeneous.
AlNi(3) with 1:3 Al-Ni ratio in mole.
AlNi(3) with 1:2.5 Al-Ni ratio in mole. The reduced Ni attempted to eliminate unreacted Ni. However, in my experiment, there is not much difference between two AlNi(3) samples.
The measured results have less than 0.5% difference than literature values!
Thanks to Professor Lisensky, we can easily visualize the structures of AlNi and AlNi(3).
This page was updated on Dec. 7, 2015.