Shaotao Dai

Synthesis, characterization and thermostability of barium β-diketonate with tetraethylenepentamine ligand

The metal-organic chemical vapor deposition (MOCVD) technique is a promising process for high-temperature superconductor YBa2Cu3O7−δ(YBCO) preparation. In this technique, it is a challenge to obtain barium precursors with high volatility. In addition, the purity, evaporation characteristics and thermostability of adopted precursors in the whole process would decide the quality and reproducible results of YBCO film. In the present report, the barium precursor containing 2,2,6,6-tetramethylheptane-3,5-dionate and tetraethylenepentamine ligands (Ba(TMHD)-tetraen) was synthesized and identified by FTIR, 1H NMR, 13C NMR and ESI-MS spectroscopy. Subsequently the thermal property and the kinetics of decomposition were systematically investigated by combining non-isothermal thermogravimetric analysis methods (TGA), Ozawa, Kissinger and Friedman methods. On the basis of the apparent activation energy of the evaporation process, the thermostability and evaporation characteristics of the precursors were discussed. All results show that Ba(TMHD)-tetraen has higher volatility than Ba(TMHD)2, but it is unstable and highly sensitive to the change of temperature during the whole evaporation process. Therefore, it is very important to choose suitable volatilization technology and conditions for avoiding Ba(TMHD)-tetraen breakdown (or thermal aging) during the MOCVD process.

Synthesis, characterization and thermostability of tris（2,2,6,6-tetramethyl-3,5- heptanedionato）yttrium（III）

Abstract The metal-organic chemical vapor deposition (MOCVD) technique is a promising process for high temperature superconductor YBa 2 Cu 3 O 7- d (YBCO) preparation. In this technique, the purity, evaporation characteristics and thermostability of adopted precursors will decide the quality and reproducible results of YBCO film. In the present report, tris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium(III) (Y(TMHD) 3 ) was synthesized by the interaction of yttrium nitrate hydrate with TMHD in methanol solution, and its structure was identified by FTIR, 1 H NMR, 13 C NMR and EI-MS spectroscopy. Subsequently, the thermal property and the kinetics of decomposition were systematically investigated by non-isothermal thermogravimetric analysis methods (TGA) at different heating rates in streams of N 2 , and the average apparent activation energy of evaporation process was evaluated by the Ozawa, Kissinger and Friedman methods. The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 88.9 kJ/mol.