L17 - SUMMARY FROM LAST CLASS Crystalline lattices The unit...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Dr. P. Lucas U of A MSE 110 Crystalline lattices SUMMARY FROM LAST CLASS The unit cell is the smallest repeatable building block that is replicated in three dimensions to generate the periodic crystalline structure. The space lattice is as a three dimensional net of straight line dividing all space into equal size parallelepiped corresponding to the crystal unit cell. All crystals can be described using one of 7 different unit cell geometry (7 crystalline systems). The unit cell edges defines a coordinate system with its origin at the cell corner. This coordinate system specifies the atoms position in the cell. When stating the position of an atom that has several equivalent positions, the coordinates that involve zero rather than ones are chosen. Specifying the unit cell and the atoms coordinates fully defines the crystal structure. Some crystals are conveniently described using a unit cells with repeatable lattice positions in the center of the cell or in the middle of faces. These lattice positions will have the exact same surrounding in the cell and everywhere else in the crystal. They are therefore indistinguishable. There are only 14 ways to arrange such indistinguishable lattice sites. These correspond to the 14 Bravais lattices. In a cell with n lattice sites an atom must therefore be repeated n times to produce the same atomic surrounding around each site. Example NaCl: 4 sites, 4 Na, 4 Cl.
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Dr. P. Lucas U of A MSE 110 Lattice planes: MILLER INDICES Each different crystalline structure generate different planes in different directions. Each crystalline structure will actually generate a unique set of planes with specific orientations. Because of the periodic nature of crystalline structures, many planes of atoms can be identified in different directions in the crystal lattice.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern