Thallium doped Cesium idoide is not easy deliquescence in the air and easy to process to the thin tablet. It is widely applied in energy spetrum probe.
Natrim doped Cesium idoide easy deliquesence so should apply hermeticaly.
The common charactors of them are high density, high average atomic number. These make them very efficient on γ ray and x ray detection.
CsI has more than 40% efficiency than NaI and have no delevage plane. It is sofe and can be make various sharpes detetors.