Zachariasen's Rules

Question 1

Describe how likely it is than an oxide material will form a glass
[on regular cooling of a melt

Answer 1

Zachariasen’s Rules

Question 2

Rule 1

Answer 2

Anion coordination [wrt network-forming cations] is low

Question 3

Rule 2

Answer 3

Network-forming cation coordination is low (3 or 4)

Question 4

Rule 4

Answer 4

At least three corners of network-forming polyhedral should be shared with other network formers.

Glass =>3D=> min. 3 corners shared=>Si:O ratio is at least 0.4 (2:5)

Question 5

Rule 3

Answer 5

Network-forming cation polyhedral share CORNERS ONLY

Question 6

Rule 5

Answer 6

Modifier cations (if present) will be large with low charge [bottom left]