Preferred compounds include Bi oxide, Co oxide, Cu oxide, {TAIL ~ Fe oxide}, Mn oxide, and {HEAD ~ Pr oxide}, and optionally Ag oxide 
Preferred compounds include Bi oxide , Co oxide , Cu oxide , { TAIL ~ Fe oxide } , Mn oxide , and { HEAD ~ Pr oxide } , and optionally Ag oxide
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH