Search for indium and thallium based high density scintillators

We have studied a set of 8 double oxide compounds of indium and 2 double oxides of thallium. Of these, most indium compounds have density over 6 g/cm/sup 3/ and most of thallium compounds have densities over 7 g/cm/sup 3/. We have doped them with cerium and terbium. None of them scintillates except for InTaO/sub 4/:Ce and InTaO/sub 4/:Tb that scintillate with roughly 4% and 8% of BGO light output respectively. In this paper we report on the reason for choosing indium and thallium compounds, method of their synthesis and examine the reasons for the lack of scintillation in these compound.