None - Crystal Structure Ashraf Bastawros...

Info icon This preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Material Sciences and Engineering, MatE271 Material Sciences and Engineering MatE271 1 Crystal Structure Ashraf Bastawros \~bastaw\courses\Mate271.html Week 2 Material Sciences and Engineering MatE271 Week 2 2 - Define basic terms in crystallography - Be able to identify 7 crystal systems and 14 Bravais lattices - To compare and contrast the structures of metal, ceramics and polymer materials - Explain the three most important structures for metals - Calculate atomic structure densities Goals for this unit
Image of page 1

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

View Full Document Right Arrow Icon
Material Sciences and Engineering, MatE271 Material Sciences and Engineering MatE271 Week 2 3 Crystal Structure and Periodicity ° Crystalline Materials atoms are in an ordered 3-D periodic array Single crystal or polycrystalline solids ( metals, ceramics, semiconductors, some polymers ) ° Amorphous Materials short range order ( glasses, many polymers ) ° Intermediates Material Sciences and Engineering MatE271 Week 2 4 Crystal Structure and Periodicity Lattice - a 3-D array of positions in space. A geometric framework on which to hang atoms Unit Cell - the smallest repeat unit which defines the crystal structure 2-D 3-D 2-D Note - In these cases, there is one atom centered on each lattice site
Image of page 2
Material Sciences and Engineering, MatE271 Material Sciences and Engineering MatE271 Week 2 5 Simple Cubic (SC) Lattice Crystal Structure Hang 1 atom on each lattice point SC lattice and crystal structure a = 2R Where: R = atomic radius atom a = lattice parameter Material Sciences and Engineering MatE271 Week 2 6 Axes Labels Lattice constant - a, b and c are lengths of edges - α , β , γ are angles ( α is across from a, etc.) a b c α β γ By convention origin - 0,0,0 z y x
Image of page 3

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

View Full Document Right Arrow Icon
Material Sciences and Engineering, MatE271 Material Sciences and Engineering MatE271 Week 2 7 Crystal Systems ( 7-systems ) Tetragonal a=b c α=β=γ=90 Cubic a=b=c α=β=γ=90 Orthorhombic a b c α=β=γ=90
Image of page 4
Image of page 5
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