{TAIL ~ Spinel type MgAl2O4} is substituted into {HEAD ~ a basic spinel structure} for structural stability 
{ TAIL ~ Spinel type MgAl2O4 } is substituted into { HEAD ~ a basic spinel structure } for structural stability
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH