Concepts

Crystal structures

Overview

This is a set of lattice models belonging to the hexagonal crystal family.

Details

Equipment

• [1] Magnesium model
• [1] Zinc model
• [1] Graphite model
• [1] Wurtzite model
• [1] Cadmium chloride model
• [1] Cadmium iodide model
• [1] Molybdenum disulphide model
  

Script

This is a show-and-tell demo. You choose which models you want to highlight. Details of the models follow.

• Magnesium
  HCP lattice
  Space group 194
  
• Zinc
  HCP lattice, 15 atoms, showing conventional cell and coordination
  Scale 2.5 cm = 1 Å
  Space group 194
  
• Graphite (alpha phase)
  Honeycomb lattice
  C-C in-layer distance: 1.42 Å
  Space group 194
  
• Wurtzite
  Forms two interlocking lattices of HCP ions
  Space group 186
  
• Cadmium chloride
  Chloride ions form CCP arrangement with cadmium ions filling octahedral holes
  Scale 2.5 cm = 1 Å
  Space group 166
  
• Cadmium iodide
  Iodide ions form HCP arrangement with cadmium ions filling octahedral holes
  Scale 2.5 cm = 1 Å
  Space group 164
  
• Molybdenum disulphide
  Probably to scale 2.5 cm = 1 Å
  Space group 194
  
• Calcite
  Lattice looks like a distorted cubic arrangement, like a rhombohedral sodium chloride, with alternating calcium and carbonate groups
  Space group 167

Additional Resources