... most materials are the build up of several crystal structures, the material properties are determined
based on the amount of exposed material from each crystal and the individual crystal structure. The
most common crystal structures are body centric cubic (bcc), face centric cubic (fcc), and hexagon ...
1. Show that only four types of rotational symmetry are possible.
2. Why it is not possible to have 5, 7 or higher order symmetry in crystallography?
3. What is point group? How many point-groups are possible?
4. Find out the Hermann-Mauguin symbol for a cube.
5. For a point at xyz write a tran ...
... Next, step back from the single crystal and look at groupings of crystals. A material may
have different levels of crystalline.
a. Single crystal: entire substance formed from one large crystal
... the mineral.
A mineral is a solid because of the close
packing of its ions or atoms and the strong
forces of attraction between them
The hardness of a mineral depends on the
arrangement of its ions or atoms
Carbon forms diamond, the hardest natural
Carbon also forms graphite, a very soft
... Types of Diffusion
Self-diffusion: movement of atoms through their own
Interdiffusion (impurity diffusion): diffusion of species not part of
the crystal structure
Example: movement of Ni through the lattice of Cu
... Programme worth 6 ECTS credits for the second-level degree in physics:
1. From the Drude model to the Sommerfeld theory of metals.
Limits of the free electron model.
2. Structural order and disorder. The crystal lattice. The reciprocal lattice.
Diffraction of x-rays by crystals. Bravais lattices and ...
... the emitted x-rays have the following characteristic wavelengths: Kα = 71.08 pm and Kβ = 63.09 pm. These xrays are collimated into a beam by the collimating slit and the incident beam makes an angle θ with the surface
of the crystal sample. The detector, a Geiger-Müller tube is mounted in such a way ...
... The chemical composition may vary between end members of a mineral system. For example the
plagioclase feldspars comprise a continuous series from sodium-rich albite (NaAlSi3O8) to calcium-rich
anorthite (CaAl2Si2O8) with four recognized intermediate compositions between. Mineral-like substances
... pharmaceuticals are delivered orally and must dissolve in the gastrointestinal fluid to be absorbed by
the body. Drug dissolution rate is proportional to surface area, so a common formulation strategy is to
structure drugs as small as possible to maximize surface area. A simple approach to create ve ...
... discrete steps by a set of basis vectors.
•In 3-D, there are 14 unique Bravais lattices.
All crystalline materials fit in one of these
In 3-D, the translation vector is
r = ha + kb + lc
... 5. What are unit cell, lattice constant and the number of atoms per unit cell? What is the number of
atoms per unit cell for BCC, FCC and HCP?
Answer: Unit cells can be defined as small repeat entities that describe crystal structures. Unit cells are
usually parallelepipeds or prisms that have three ...
In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms, ions or molecules in a crystalline liquid or solid. It describes a highly ordered structure, occurring due to the intrinsic nature of its constituents to form symmetric patterns.The crystal lattice can be thought of as an array of 'small boxes' infinitely repeating in all three spatial directions. Such a unit cell is the smallest unit of volume that contains all of the structural and symmetry information to build-up the macroscopic structure of the lattice by translation.Patterns are located upon the points of a lattice, which is an array of points repeating periodically in three dimensions. The lengths of the edges of a unit cell and the angles between them are called the lattice parameters. The symmetry properties of the crystal are embodied in its space group.A crystal's structure and symmetry play a role in determining many of its physical properties, such as cleavage, electronic band structure, and optical transparency.