These compounds may be in a crystalline state having {HEAD ~ metallic cations} of two different valences, or {TAIL ~ electronic states}, in the inorganic crystal 
These compounds may be in a crystalline state having { HEAD ~ metallic cations } of two different valences , or { TAIL ~ electronic states } , in the inorganic crystal
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH