P1254156745irbEa

1
Systematics in Polar Intermetallic Structures
Compounds with 2, 3 Cations Tightly
Encapsulated in Polyatomic Anionic Networks
Coulombic Effects
Tetragonal 1. BaIn4 a good fit
2. SrIn4
Sr
Ba
In
lower symmetry, smaller cavities
In layer and In dimers define tight cavities.
Smaller Sr 2 would rattle in same cavities
6-rings
note 5-rings
Network substitutions restore the fit of a
BaIn4-type structure
3. SrAuIn3, a good fit again
4. SrMg1.5In2.5 a good fit too.
In layer
5050 AuIn, shorter bonds (relativistic effect)
7525 MgIn in yellow layer decreases bond
distances in and around the layer.