Cesium-containing layers preparation by chemical vapor depositon or related methods is very scarce, despite strong interest of application of cesium-containing materials (such as  cesium tellurides and antimonides) as photocathodes with much lower work function and efficiency. Cs-containing K and Na niobates and tantalates are promising materials for electrooptic applications.

            The main reason of presence of such a “white spot” in CVD research is the lack of volatile compounds of cesium that can be easily applied for the preparation of cesium-containing materials from vapor phase. As cesium is the most electropositive element in periodic table (electronegativity 0.79 by Pauling), it has tendency to form ionic or polymeric compounds that are difficult to vaporise. Also, because of large radius of cesium atom (atomic radius 260pm (ionic radius 167pm), the largest of all stable elements) it is difficult to saturate its coordination sphere (coordination sphere saturates at CN = 8) and prepare a monomeric compound with low molecular mass that is essential for achieving good volatility.

In Table is presented comparison of known vapor pressures of cesium CVD precursors.