The Thermal and Radiation Annealing Reactions of Recoil Damage in Solid Cobalt (III) and Chromium (III) Tris-Acetylacetonates

Abstract:

[en] This paper reports results of an investigation on the influence of defects and of solid state dilution on the radiation, photo and thermal annealing reactions of (n, y) recoil fragments, formed by pile irradiation of solid Co (lII) and Cr (lII) tris-acetylacetonàtes. The introduction of defects in crystals of chromium tris-acetylacetonate and cobalt tris-acetylacetonate has a profound influence, both on the initial retention as well as on the kinetic behaviour of the Cr 51 and Co 60 recoil fragments. In fact the irradiation of the solids investigated with different doses of Co 60 γ rays (0-50 Mrad), as well as their thermal decomposition and/or quenching (50-150 C) after different heating times (20 min-10 h) prior to the neutron irradiation, lead to a lowering of the initial retentions (down to 50% of their''normal''values) and to a slowing-down of the rates of isothermal annealing. Similar effects were found for crystals irradiated with different pile doses (from 15 kWh to 300 kWh) at room temperature. A detailed investigation of this thermal decomposition as well as the radiolysis of the cobalt complex has prompted a reinterpretation of the recoil chemistry of this compound. The anomalies found in another investigation, including the diminishing of the retention by dilution of the Co (III) acetylacetonate in solid matrixes, are now explained by the competition between the defects (generated by different methods) and the recoil fragments for the capture of electrons, which is necessary for the reformation of the target molecule. Although the chromium complex is more stable than the cobalt compound (both towards heat and ionizing radiation) similar effects were found for this …

Año de publicación:

1965

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Fuente:

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