Purification and UV-VIS Light Absorption Property of Source Materials for CVD of High-Tc Superconducting Films

Abstract
Purification and spectral properties of source materials for CVD of high-T c superconducting films have been investigated quantitatively. Based on elemental analysis, TG, IR spectroscopy, and 1H-NMR spectroscopy, sublimation was verified to be satisfactory for the purification of Bi(C6H5)3, Ca(DPM)2, and Cu(DPM)2 (DPM: dipyvaloylmethane). Sr(DPM)2 was not sufficiently purified by the sublimation alone, but recrystallization from an ethanol solution in advance improved the purity of the sublimate, as verified by a significant decrease in the sublimation temperature. The UV-VIS spectra revealed that Bi(C6H5)3, Sr(DPM)2, Ca(DPM)2 and Cu(DPM)2 had high absorption coefficients at wavelengths around 254 nm, suggesting high possibilities of their photochemical decomposition by light irradiation from a low-pressure mercury lamp.