ρ = Z M / (Nₐ Vmaille)ρ: g/cm³ if M is in g/mol and Vmail is in cm³; Z: number d of entities per mesh.
Use when: The definition of Z and M must correspond to the same chemical entity.
Interpreting crystal structures
Connect mesh, periodic network and atomic organization.
What is happening?
A crystal has a periodic organization described by a network and a pattern. Crystal systems classify lattice geometries; Bravez networks describe the possible translations.
The same composition can present several structures depending on the conditions. The crystal system alone therefore does not make it possible to identify a material or predict all its mechanical properties.
The formulas, with their conditions.
2 d sin θ = n λd and λ: lengths in the same unit; θ: Bragg angle; n: integer.
Use when: Bragg diffraction condition; the instrument often displays 2θ.
Where is this principle used?
Diffraction laboratory
Identify crystalline phases.
Metallurgy and ceramics industry
Understand structural transformations and material properties.
What to observe in the experiment
Compare a cubic mesh and a tetragonal mesh: note the lengths and angles that differ, then distinguish mesh and atom.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian