Chemical effects of radiative thermal neutron capture. Part 8.—Retention in solid solutions of chromates

Maddock, A. G.; Vargas, Josimar

doi:10.1039/tf9615700992

Cited by 15 publications

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“…In a classic paper of 1940 [3][4][5][6]. Thus, since 100% annealing is experimentally observed in potassium Chromate [3][4][5]7], these assumptions require that all the recoil 51 Cr atoms maintain the +6 oxidation state (as *Cr0 4 -, *Cr0 3 , *Cr0 2 + 2 , »CrO^ and possibly, i|t Cr+ e ).…”

Section: Introductionmentioning

confidence: 98%

“…Thus, since 100% annealing is experimentally observed in potassium Chromate [3][4][5]7], these assumptions require that all the recoil 51 Cr atoms maintain the +6 oxidation state (as *Cr0 4 -, *Cr0 3 , *Cr0 2 + 2 , »CrO^ and possibly, i|t Cr+ e ). Upon consideration of the aqueous chemistry of these species, the thermal annealing reaction in solid potassium Chromate was proposed to be [2-6] :…”

Section: Introductionmentioning

confidence: 99%

“…*Cr0 2 + 2 appears as Chromate after dissolution. An "activated exchange" mechanism for the annealing reaction of the chromium (VI) species was also considered [3,4,6] and rejected [5].…”

Section: Introductionmentioning

confidence: 99%

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Transfer Annealing in Chromic-Doped Potassium Chromate

Apers

Collins

et al. 1964

Radiochimica Acta

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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.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Transfer Annealing in Chromic-Doped Potassium Chromate

Apers

Collins

et al. 1964

Radiochimica Acta

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“…Table 1 displays the corresponding quadrupole coupling parameters. Considering the complexity of the original molecule, it should be expected that all contributions usually considered to be responsible for the initial retention fraction [9] should be inoperative in the case of Hf(M) 4 . Our results are consistent with this expectation but disagree with the results obtained by BOUSSAHA et al in the same compound [8], This discrepancy may find an explanation in differences of the irradiation conditions, particulary in terms of the reactor temperatures.…”

Section: Resultsmentioning

confidence: 99%

Differential Perturbed Angular Correlation Measurements in Reactor Irradiated and Thermal Annealed Tetrakis-(dl-mandelate) Hafnium(IV)

et al. 1978

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Tetrakis (dl-mande!atej hafniumflV) / y,y angular correlation Summary Retention and thermal annealing effects following (n, 7) reaction were measured in solid tetrakis(dl-mandelate) hafnium(IV) by time differential measurements of the 133-482 keV y, y angular correlation of 181 Ta. The irradiation of the inactive compound with thermal neutrons 3 leads to a large spreading of the quadrupolar interaction parameters Q,(/) = s + V" which does not allow the characterization of a definite radioactive ^0 hafnium atom site. n ~ The thermal treatment permitted the detection of the quadrupolar interaction parameters as they were determined in the labelled compound and the analysis of the data revealed an important proportion of molecular reformation. the Legendre polynomials and τ the mean-life of the intermediate level of angular momentum I. The value of fc max depends on the spins of the levels and on the multipolarities of the gamma transitions. The coefficient s G fc (f) contain all the information on the perturbation. In the case of a spin I = 5/2 of the intermediate level, s kn cos ( u n t ) e -(δ u> n t+ 2 <+>n Τβ)

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“…This phenomenon -a kind of recrystallization from the debris of the disordered lattice -has been designated as "template effect" [20]. Another indication for proper recombination during thermal annealing are the increasing retentions in mixed crystals such as K 2 Cr0 4 -K 2 BeF 4 [20][21][22][23][24][25] and KMn0 4 -KBF 4 [26] in which the matrix component does not contain the proper ligand.…”

Section: Introductionmentioning

confidence: 98%

Chemical Effects of Nuclear Transformations in Mixed Crystals 8. Thermal Annealing of ¹⁸⁶Re in Neutron Irradiated K₂ReBr₆-K₂SnCl₆ Mixed Crystals. I

Müller

1983

Radiochimica Acta

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In Κ, ReBr 6 -K 2 SnCl 6 mixed crystals the nuclear process " 5 Re (n, y) 1,6 Re produces according to the chemical analysis all species 1 " ReBr"Cl^" (n = 0 ... 6) and (from excited or interstitial 1,6 Re recoils) 1 " ReO;. Upon thermal annealing 1 " ReO; decreases and the fractions of all " 6 ReBr"CljI" species increase. Approximately one third of the annealing occurs at 50°C producing merely 1 " ReBrJ ~ which is strong evidence for a proper recombination of 1 " Re with its six originally coordinated Br ligands. The remaining annealing proceeds with increasing temperature and is due to the reaction of 1 " Re recoil atoms with halides, both CI and Br, from the lattice. As there is no preference for a special species no conclusions can be drawn concerning the lattice site where these reacting '"Re recoils come to rest.

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Chemical effects of radiative thermal neutron capture. Part 8.—Retention in solid solutions of chromates

Cited by 15 publications

References 0 publications

Transfer Annealing in Chromic-Doped Potassium Chromate

Transfer Annealing in Chromic-Doped Potassium Chromate

Differential Perturbed Angular Correlation Measurements in Reactor Irradiated and Thermal Annealed Tetrakis-(dl-mandelate) Hafnium(IV)

Chemical Effects of Nuclear Transformations in Mixed Crystals 8. Thermal Annealing of ¹⁸⁶Re in Neutron Irradiated K₂ReBr₆-K₂SnCl₆ Mixed Crystals. I

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Chemical effects of radiative thermal neutron capture. Part 8.—Retention in solid solutions of chromates

Cited by 15 publications

References 0 publications

Transfer Annealing in Chromic-Doped Potassium Chromate

Transfer Annealing in Chromic-Doped Potassium Chromate

Differential Perturbed Angular Correlation Measurements in Reactor Irradiated and Thermal Annealed Tetrakis-(dl-mandelate) Hafnium(IV)

Chemical Effects of Nuclear Transformations in Mixed Crystals 8. Thermal Annealing of 186Re in Neutron Irradiated K2ReBr6-K2SnCl6 Mixed Crystals. I

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Chemical Effects of Nuclear Transformations in Mixed Crystals 8. Thermal Annealing of ¹⁸⁶Re in Neutron Irradiated K₂ReBr₆-K₂SnCl₆ Mixed Crystals. I