Materials Science and Engineering/Doctoral review questions/Crystallography

From Wikiversity
Jump to: navigation, search

Contents

Tensor 1[edit]

Propagation of Waves Along One-Dimensional Crystal with Two Kinds of Atoms[edit]

  • Force-balance equations
  • Trial solution
  • With a given value of k, there are two different waves of angular frequency that may be propagated

Interpretation of the Solutions[edit]

Solutions of Small k[edit]
Solutions with positive sign at k = 0[edit]
Solutions with negative sign at k = 0[edit]

Acoustic and optic branch

Solutions with k = kmax[edit]
Displacements at kmx[edit]

Correspondence to the Identical-Atom Problem[edit]

The optical mode is not present in the case with one kind of atom.

Tensor 2[edit]

Wave Propagation in a Continuous One-Dimensional Medium[edit]

The wave velocity is independent of \lambda

 v = \sqrt{\frac{c}{\rho}} = \sqrt{ \frac{\beta a^2}{M}}

Wave Motion on a Row of Identical Atoms[edit]

Total Number of Vibrational Modes that May be Supported by the Crystal[edit]

The number of vibration modes that can be supported is equal to the number of atoms in the crystal

Tensor 3[edit]

Propagation of Elastic Waves in Crystals[edit]

Relation of stress and strain in a cubic crystal

Tensor 4[edit]

Tensor 5[edit]

Conventions of Relabeling Stress, Strain, Stiffness, and Compliance in Matrix Notation[edit]

Condensation of Tensor to Matrix Notation[edit]

Strain in Terms of Stress[edit]

Stress in Terms of Strain[edit]

Tensor 6[edit]

Property Tensors[edit]

Triclinic[edit]

Monoclinic[edit]

Orthorhombic[edit]

Tetragonal[edit]

Tetragonal[edit]

Cubic[edit]

Isotropic[edit]

Cauchy Relation[edit]

  1. Central Forces
  2. Each atom at center of symmetry
  3. No initial stress

Tensor 7[edit]

Some Basic Relations in Electromagnetism[edit]