Transfer Annealing in Chromic-Doped Potassium Chromate

Abstract

RadiochimicaAct» As E-p can be replaced by its numerical value obtained in (8) and each quantity in the last term of (23) is known from experiments, we obtain : Ε έ ' = 8.5 -3.0 = 5.5 kcal/mol.This value corresponds to the experimentally observed value (5.6 kcal/mol) which is already shown in (9). Thus, such chemical reactions as are shown in (13) and (14) might give a possible explanation for the annealing process of [CO*(NH 3 ) 6 C1] 2 + or Co* 2 +. The above mentioned experimental results and discussion would lead us to the following model for the mechanism of the recoil phenomena of 38 C1 or M Co in the [Co(NH 3 ) e ]Cl 3 crystal. The recoil atoms of 38 C1 or eo Co which are produced by the (η, γ) -reaction in the [Co(NH 3 ) e ]Cl 3 crystal have a recoil energy of the order of 10,000 kcal/mol and can readily break the bond of the complex salt. Thus, local fragmentation occurs and systems consisting of unstable fragments are produced in the neighborhood of the recoil atoms. These fragments are immediately rearranged in the hot-zone yielding a group of such chemical species as [CO(NH 3 ) 6 ] 3 +, [CO(NH 3 ) 5 C1] 2 +, CO 2 + and/or Co 3 +, NH 3 ,Cl~, etc. These chemical species are considered to be rather stable, but there are still some physical defects and instabilities in the crystal lattice as well as some local disturbances in its composition. In these unstable systems, chemical reactions occur between the above mentioned species which lead to more stable systems. These processes are to be observed as the thermal annealing shown in Fig. 2, 3, or 4. We consider them to be of an essentially chemical nature, and the backreaction of (11), or the reactions of (13), (14) may well occur among them. By this model, the formation of 38 C1 or ®°Co in the form of [CO(NH 3 ) 5 C1] 2 + can also be explained. SummaryThermal treatment on chromic ( sl Cr)-doped potassium Chromate results in the incorporation of 51 Cr activity into the Chromate form. Measurements of the isothermal kinetics of this incorporation give "annealing" curves similar to those obtained in Szilard-Chalmers studies on potassium Chromate. It is concluded that transfer annealing may play an important role in Szilard-Chalmers annealing processes in potassium Chromate.

Radiation Effects on 51Cr(III)-Doped Chromates and Other Oxy-Salts

“…This method was found not to be suitable for analysis of the 61 Cr(III)-doped sulphate salts. In this case an alumina column separation [3,6] was used for determining the 61 Cr(VI) yield. The dissolution of samples irradiated at liquid nitrogen temperature took place at ~ 2 °C by rapid stirring.…”

Comment on "Phenomena Involving Neutron Capture by Selected Cobalt Complexes“

“…Our transfer annealing experiments [4][5][6] seem to show that the recoil cobalt does finally stabilize as Co++. Similar experiments with various oxyanions [7][8][9] show that in these matrices also, the recoil atom stabilizes in a low charge state.…”

Chemical Recovery of (n, γ) Recoil Co(II) in Nitratopentamminocobalt(III) Nitrate

“…Plausibly a small part of the recombination process is taking place by solid state isotopie exchange reaction as in the case of hydrated Cr 3 + ion embeded in a Chromate matrix [19] or iodide in an iodate matrix [20]. This view is supported by the fact that the recovery data in the pseudo-plateau region are not fitting the correlated reaction kinetics indicating the occurrence of different mechanisms.…”