For Ce3+-doped scintillators, the Ce4+ model is widely used in the explanation of enhancement effect of M2+ (Ca2+,Mg2+,Zn2+) ions.
https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8364630
If this model is true, then we can expect that Ce4+-doped material is a kind of promising scintillators. Why there is no such 100% Ce4+-doped scintillator reported?
Suggestions welcomed!