Undergrad What factors influence the crystal structure of metals?

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SUMMARY

The crystal structure of metals is influenced by factors such as electronic structure, coordination number, and packing fraction. For instance, Strontium (Sr) exhibits a Face-Centered Cubic (FCC) structure, while Barium (Ba) adopts a Body-Centered Cubic (BCC) structure despite having a lower packing fraction. The discussion highlights that metals like iron can change their crystal structure in response to temperature and pressure variations. Ultimately, the determination of bond geometry in metals is a complex interplay of electronic structure, entropy, and density under applied pressure.

PREREQUISITES
  • Understanding of crystal structures, specifically FCC and BCC configurations.
  • Knowledge of electronic structure and its impact on bonding.
  • Familiarity with concepts of coordination number and packing fraction.
  • Basic principles of thermodynamics related to temperature and pressure effects on materials.
NEXT STEPS
  • Research the impact of temperature and pressure on the crystal structure of metals, focusing on iron.
  • Explore the relationship between electronic structure and bond geometry in metals.
  • Study the concept of entropy in relation to phase transitions in metallic materials.
  • Investigate the differences in packing efficiency between FCC and BCC structures.
USEFUL FOR

Materials scientists, metallurgists, and students studying solid-state physics or chemistry will benefit from this discussion, particularly those interested in the factors influencing the crystal structures of metals.

sghan
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What determines the crystal structure taken by metals? For example Sr has FCC and Ba BCC. The packing fraction is greater for FCC. However, due apparently to coordination number and number of "next nearest" neighbors, BCC is favored in the case of Barium despite its lower packing fraction. The introductory texts I am reading claim metal bonds are mostly isotropic. Sr and Ba have the same valence shells. Nevertheless, is electron structure the key to determining bond geometry?
Thanks,
Simi
 
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There is no simple answer to this. Some metals, e.g. iron, even change their crystal structure as function of temperature and pressure. In the end it comes down to a balance between electronic structure, entropy and density (in case of externally applied pressure).
 
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