Volatile caesium-containing compounds of Cs[Y(β-diketonato)4] type: Thermal behaviour in condensed and gas phases

• The volatile complexes of MI[Y(β-diketonato)4] (MI = Cs, Na, K) were the objects of this investigation.
• Thermal behaviour was studied by TG and DSC, vapour pressures were measured by transpiration and Knudsend’s effusion methods.
• The thermodynamic parameters of phase transitions and equilibriums were calculated.
• The ways of thermodecomposition of one Cs-containing complex’s vapour in vacuum and oxygen presence were proposed.
• Using thermochemical data Cs2O-containing films were obtained by Metal–Organic Chemical Vapour Deposition for the first time.

The present work deals with the investigation of the thermal properties of bimetallic volatile Cs-containing compounds of MI[YL4] type. The influence of ligand (MI = Cs, L = CF3COCHCOR, R = tBu – ptac, CF3 – hfac, Me – tfac, Ph – btfac) and alkali metal (L = ptac, MI = Na, K, Cs) on thermal properties of this type of complexes was investigated using thermogravimetry, differential scanning calorimetry and two independent methods of vapour pressure measurement, viz. flow (transpiration) and Knudsen’s effusion. Thermal decomposition of Cs[Y(ptac)4] was studied in vacuum and in the presence of oxygen by means of in situ high-temperature mass spectrometry. The routes of vapour decomposition on a heated surface are proposed. Complex Cs[Y(ptac)4] was found to be perspective precursor for production of Cs-containing films by Metal–Organic Chemical Vapour Deposition (MOCVD). The low-pressure MOCVD experiments have shown that films containing caesium oxide could be deposited using this precursor.

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