Thermal study of CVD metal–organic precursors
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The pressure of the saturated and unsaturated vapors of Zr(thd)4 and Y(thd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) has been measured by the static method with a membrane-gauge manometer in a wide interval of temperatures: 473–623 K for Zr(thd)4 and 424–605 K for Y(thd)3. As a result of this study, the thermal stability of compounds under study was reliably established. From the unsaturated vapor data, it was concluded that Zr(thd)4 passes into a gas phase as a monomer up to its decomposition while gas phase over Y(thd)3(cond) contains some polymers. Equations approximating the dependences of saturated vapor pressure on temperature and also the enthalpies and entropies of sublimation [Zr(thd)4, Y(thd)3] and vaporization [Y(thd)3] were obtained. The thermal behavior of the complexes was also investigated by differential scanning calorimetry, and the thermodynamic parameters of phase transitions (Ttr, ΔtrH Ttr ° ) were determined. Obtained information was compared with previous published data.
KeywordsZirconium and yttrium beta-diketonates Static method with a membrane-gauge manometer Scanning calorimetry Enthalpy Entropy
This work was partially funded by Russian Scientific Foundation according to the research Project No. 16-19-10325. We also thank Federal Agency for Scientific Organizations for funding.
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