THERMOGRAVIMETRIC AND ESR STUDIES OF POLYMER METAL PRECURSORS FOR HIGH-TEMPERATURE SUPERCONDUCTORS/

Bi-Sr-Ca-Cu complexes of poly(methacrylic acid) (PMAA) and cresol novo lac, which are precursors for high-temperature superconductors (HTSC) and Cu complexes of those polymers were investigated by ESR spectrosco py and thermogravimetry. In the PMAA samples three different kinds of Cu2+ species were detected: i) Cu2+ pairs, ii) isolated Cu2+ ions and iii) Cu2+ clusters. While Cu2+ pairs are the main species at low Cu co ncentrations, clusters become dominant at high Cu contents. In the nov olac samples Cu2+ was only detected in isolated sites and clusters. Th e introduction of Cu ions lowered the thermal stability of the polymer s and led to a stepwise decomposition. In the PMAA samples the first d ecomposition step at approximate to 220 degrees C is caused by the Cu2 + pair complexes.