Effects of Fe3+ on electron spin echo signals in zeolites

Abstract

The presence of paramagnetic Fe³⁺ impurities in zeolites can interfere with electron spin echo studies to decrease echo intensity. To study these effects Fe³⁺ as iron oxide and as structural Fe³⁺ was extracted from zeolites with an extraction procedure using ethylenediaminetetraacetic acid in the presence of aluminium nitrate. Comparison of electron spin echo signals of exchanged Cu²⁺ before and after iron extraction in X, Y and mordenite zeolites is reported. Commonly occurring quantities of Fe³⁺ influence both three-pulse and two-pulse echo signals by decreasing the echo intensity and by increasing the echo decay rate.