CHEMICAL-STABILITY OF CVD SOURCE MATERIALS FOR HIGH-T(C) SUPERCONDUCTING FILMS

The stability of chemical vapor deposition (CVD) source materials for high-T(c) superconducting films was examined by H-1-NMR (nuclear magnetic resonance), C-13-NMR, IR (infrared) absorption, and TG-DTA (thermogravimetry and differential thermal analysis) measurements. Highly purified Ca(DPM)2 (DPM: dipyvaloylmethane: (CH3)3CCOCHCOC(CH3)3) and Sr(DPM)2, utilizing recrystallization and sublimation, easily decomposed at room temperature and changed their thermal properties when they were handled and stored in air or even in an Ar atmosphere without removing adsorbed species such as water. The stability increased by removing a trace of adsorbed species and storing in an Ar atmosphere at -30-degrees-C. Bi(C6H5)3 and Y(DPM)3 showed higher chemical stability than Ca(DPM)2 and Sr(DPM)2.