Let's Make Diamonds! Let's Make Diamonds!By Cecily Fitzpatrick (Mount Sinai High School), Ninfa Gatha (East Islip High School), Katie Hamilton (Riverhead High School), Laura Kaell (Ward Melville High School), Mariah Martin (Riverhead High School), and Kristie Wright (Port Jefferson High School)
This educational program was was a collaboration between the Center for High Pressure Research and the Project WISE program at the University at Stony Brook. Funding was supplied by the National Science Foundation. The Center for Excellence and Innovation in Education has also supported the Let's Make Diamonds! program.
The outermost layer of the earth, the crust, contains only 1% of the entire earth's mass. The crust extends 60 km below the earth's surface. Beneath the crust is the mantle, which ranges from 60 km to 2900 km. Below the mantle is the outer core which is composed of liquid iron mixed with other elements in smaller quantities. This section occurs between 2900 km and 4980 km. The center of the earth is referred to as the inner core. This semi-solid mass is composed mostly of iron, and exists between 4980 km and 6370 km from the earth's surface.
Layers of the Earth
Pressure equals force/area. The pressure within the earth ranges from 1 atmosphere to 3.5 million atmospheres. One atmosphere equals 101,000 Pascals. As depth within the earth increases, the pressure will also increase.
The temperature ranges from 25 to 4000 degrees Celsius. The maximum temperatures occur in the inner core, while the minimum temperatures are achieved at the crust.
The chemistry of the earth is comprised largely of the elements Mg, Si, Al, Ca, Fe, and O. The crust and mantle are made up of silicates, oxides, and metals. The deepest rocks are from 200 to 300 km in the earth and an example of one of these would be kimberlite, which contains diamond.
After learning the backround material on how diamonds are made, we began the tasks to create our very own diamond! We broke into groups, each having its own component of the project to work on.
Students filing pyrophyllite
One group worked on creating the octahedron. This contained a zirconia cylinder which, in turn, contained a graphite furnace. Within the graphite furnace, there was a sample cup. Inside the cup was a catalyst, tiny seed diamonds, and graphite discs.
While the octahedron was being made, the other group was dressing the eight tungsten carbide cubes. We used balsa wood as spacers between four of the cubes. In addition, pyrophyllite was cut and filed to make six short and six long gaskets which were placed on the other four cubes.
Tungsten carbide cubes with Pyrophyllite
gaskets
The two groups then joined and began working together to work on the cube assembly. The octahedron was placed in between the anvils. The final cube was sealed and ready to be placed in the Kennedy Press where the diamonds would be made.
Kennedy Press
During the analysis of our diamonds we found many important properties. We tested our diamonds by a process called x-ray diffraction. We compared our graph to the graph of a known diamond, to see if the peaks and valleys matched. We also compared our graph to a graph of a known graphite disk, to see whether our diamond contained more properties of the graphite or of the diamond.
X-ray diffractometer
The second test performed was a silicon carbide scratch test. Since scratches we made from the diamond sample were visible, we concluded that the sample contained hardness properties of a diamond.
We also viewed our sample under a binocular optical microscope connected to a television screen. Under the microscope we could see the physical properties of our sample including color and luster. We noticed our diamond sample was colorless and was adamantine, due to its high optical index.
Binocular optical microscope
equipped with video camera