pyrochlore

Structural typepyrochlore
Common namepyrochlore
Definitionfcc lattice of cations
with X anions occupying all A2B2 tetrahedral voids (¾ of all t-voids)
and Y anions occupying all A4 tetrahedral voids (1/8 of all t-voids),
B4 tetrahedral voids are empty
Prototype(NaCa)Nb2O6F
Pearson symbolcF88
Space group227 Fd-3m Oh7
Chemical formulaA2B2X6Y
Bondingionic
Atomic positions  A (16d)  5/8  5/8  5/8  (marked by C)
 B (16c)  1/8  1/8  1/8  (marked by N)
 X (48f)   xi   0    0   (marked by S)
 Y  (8b)  1/2  1/2  1/2  (marked by O)
Coordination
SublatticesAB – fcc
PDB filespyrochlore (in ideal coordination)
Parametersξ≈1/4
Special valuesideal tetrahedral coordination of X anions for ξ=1/4
SubstancesDy2Ti2O7