Abstract
An investigation was made into the nature of paramagnetic centers in a Tc/Al2O3 system under varying conditions as to heat treatment and technetium content, and in O2 and CO adsorption environments. It was found that in the case of reduction at 573 K Tc2+ ions and, conceivably, other ionic forms developed and stabilized on the carrier surface. After reduction at 973 K two types of electron center appeared, whose concentration increased as reduction was prolonged. Signals were observed in the low fields (3–20 mT) of the ESR spectra having g1 ≈ 13.5 and g2>30, which could be assigned to free charge carriers in a cluster of metal atoms or ions. Adsorption of O2 at 300 K caused O −2 ion radicals to form on the surface of the reduced Tc/Al2O3 samples, both electron centers and technetium ions constituting the electron donors. In the case of CO adsorption paramagnetic (CO) −2 particles appeared on the Tc/Al2O3 samples after prolonged exposure. On reaction with O2 two types of O −2 ion-radical with differing thermal stability were formed.
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Institute of Physical Chemistry, Russian Academy of Sciences, Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 1972–1978, September, 1992.
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Yurik, T.K., Rymar', N.N., Barsova, L.I. et al. ESR study of electron interaction in a Tc/Al2O3 system. Russ Chem Bull 41, 1531–1536 (1992). https://doi.org/10.1007/BF00863566
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DOI: https://doi.org/10.1007/BF00863566