Principle

Polycrystalline powder samples, which crystallize in the three
cubic Bravais types, simple, face-centered and body-centered, are
irradiated with the radiation from a Roentgen tube with a copper
anode. A swivelling Geiger-Mueller counter tube detects the
radiation that is constructively reflected from the various lattice
planes of the crystallites. The Bragg diagrams are automatically
recorded. Their evaluation gives the assignment of the Bragg lines
to the individual lattice planes, their spacings as well as the
lattice constants of the samples, and so also the corresponding
Bravais lattice type.

Tasks


Record the intensity of the Cu X-rays back scattered by the
four cubic crystal powder samples with various Bravais lattice
types as a function of the scattering angle.

Calculate the lattice plane spacings appropriate to the angular
positions of the individual Bragg lines.

Assign the Bragg reflections to the respective lattice planes.
Determine the lattice constants of the samples and their Bravais
lattice types.

Determine the number of atoms in the unit cell.


What you can learn about


Crystal lattices

Crystal systems

Bravais-lattice

Reciprocal lattice

Miller indices

Structure factor

Atomic scattering factor

Bragg scattering

Characteristic X-rays

Monochromatization of X-rays

Bragg Brentano geometry