Physical properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">Yb</mml:mi><mml:mi>X</mml:mi><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cu</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>(</mml:mo><mml:mi>X</mml:mi><mml:mo>=</mml:mo><mml:mi mathvariant="normal">Ag</mml:mi><mml:mo>,</mml:mo></mml:math>Au, Cd,

Sarrao, J. L.; Immer, C. D.; Fisk, Z.; Booth, C. H.; Figueroa, E.; Lawrence, J. M.; Modler, R.; Cornelius, Andrew; Hundley, M. F.; Kwei, G. H.; Thompson, J. D.; Bridges, F.

doi:10.1103/physrevb.59.6855

Cited by 152 publications

(116 citation statements)

References 46 publications

(56 reference statements)

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“…1 4 Evolution of technetium speciation determined by XANES spectroscopy. The speciation of technetium in the grout samples was determined by least squares fitting of the XANES spectra using the 24,37 The evolution of technetium speciation in the unsealed and sealed samples is addressed separately.…”

Section: Exafs Studies Of Initial Technetium Speciationmentioning

confidence: 99%

Evolution of Technetium Speciation in Reducing Grout

Lukens

Bucher

Shuh

et al. 2005

Environ. Sci. Technol.

114

182

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Cementitious waste forms (CWFs) are an important component of the strategy to immobilize high-level nuclear waste resulting from plutonium production by the U.S. Department of Energy (DOE).Technetium ( 9 9 Tc) is an abundant fission product of particular concern in CWFs due to the high solubility and mobility of pertechnetate, TcO 4 -, the stable form of technetium in aerobic environments. CWFs can more effectively immobilize 9 9 Tc if they contain additives that reduce mobile TcO 4 -to immobile Tc(IV) species. Leaching of 9 9 Tc from reducing CWFs that contain Tc(IV) is much slower than for CWFs containing TcO 4 -. Previous X-ray absorption fine structure (XAFS) studies showed that he Tc(IV) species were oxidized to TcO 4 -in reducing grout samples prepared on a laboratory scale. Whether the oxidizer was atmospheric O 2 or NO 3 -in the waste simulant was not determined. In actual CWFs, rapid oxidation of Tc(IV) by NO 3 -would be a concern, whereas oxidation by atmospheric O 2 would be of less concern due to the slow diffusion and reaction of O 2 with the reducing CWF. To address this uncertainty, two series of reducing grouts were prepared using TcO 4 -containing waste simulants with and without NO 3 -. In the first series of samples, the TcO 4 -was completely reduced using Na 2 S, and the samples were placed in containers that permitted O 2 diffusion. In these samples, all of the technetium was initially present as a Tc(IV) sulfide compound, TcS x , which was characterized using extended X-ray absorption fine structure (EXAFS) 2 spectroscopy, and is likely Tc 2 S 7 . The TcS x initially present in the grout samples was steadily oxidized over 4 years. In the second series of samples, all of the TcO 4 -was not initially reduced, and the grout samples were placed in airtight containers. In these samples, the remaining TcO 4 -continued to be reduced as the samples aged, presumably due to the presence of reducing blast furnace slag. When samples in the second series were exposed to atmosphere, the lower-valent technetium species were rapidly oxidized to TcO 4 -.KEYWORDS technetium, cement, grout, nuclear waste BRIEFS The speciation of technetium in reducing grout samples was followed using X-ray absorption fine structure spectroscopy. The reduced technetium species were susceptible to oxidation by oxygen, but nitrate had no observable effect over the duration of the experiment. MANUSCRIPT TEXTIntroduction Immobilization of the high-level nuclear waste created during plutonium production by

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Section: Exafs Studies Of Initial Technetium Speciationmentioning

confidence: 99%

Evolution of Technetium Speciation in Reducing Grout

Lukens

Bucher

Shuh

et al. 2005

Environ. Sci. Technol.

114

182

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“…1), the susceptibility χ(T ) (Fig. 2) and the linear coefficient of specific heat γ = C/T (Table 1) are taken from Sarrao et al 14 As explained in that paper, the samples were small, high quality single crystals grown in XCu flux. The specific heat was measured using a thermal relaxation technique.…”

Section: Methodsmentioning

confidence: 99%

“…The temperature of the measurement was 10K, which is considerably smaller than T K in each case. The samples utilized in these experiments were powders, typically of 50g mass, grown from the melt inside evacuated tantalum tubes for X = Ag, Mg and Zn; for X = In and Tl, a large number of single crystals grown as described in Sarrao et al 14 were powdered to form the sample. The susceptibilities of these samples were identical to those shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Slow crossover inYbXCu4(X=Ag, Cd, In, Mg, Tl, Zn) intermediate-valence compounds

Lawrence

Riseborough²,

Booth³

et al. 2001

Phys. Rev. B

Self Cite

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We compare the results of measurements of the magnetic susceptibility χ(T ), the linear coefficient of specific heat γ(T ) = C(T )/T and 4f occupation number n f (T ) for the intermediate valence compounds YbXCu 4 (X = Ag, Cd, In, Mg, Tl, Zn) to the predictions of the Anderson impurity model, calculated in the non-crossing approximation (NCA). The crossover from the low temperature Fermi liquid state to the high temperature local moment state is substantially slower in the compounds than predicted by the NCA; this corresponds to the "protracted screening" recently predicted for the Anderson Lattice. We present results for the dynamic susceptibility, measured through neutron scattering experiments, to show that the deviations between theory and experiment are not due to crystal field effects, and we present x-ray-absorption fine-structure (XAFS) results that show the local crystal structure around the X atoms is well ordered, so that the deviations probably do not arise from Kondo Disorder. The deviations may correlate with the background conduction electron density, as predicted for protracted screening.

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“…As in the case of Ce compounds, [9] the Yb-based intermetallic compounds exhibit a rich diversity of physical properties that are not completely understood. [10] The low-temperature ground states of f -electron compounds, and the quantum phase transitions between them, often generate striking quantum phenomena and phases. Quantum phase transitions, or quantum critical points (QCPs), and their effect on the physical properties at finite temperatures have attracted considerable attention since the 1990's.…”

Section: Introductionmentioning

confidence: 99%

Crossover between Fermi liquid and non-Fermi liquid behavior in the non-centrosymmetric compound Yb₂Ni₁₂P₇

Jang¹,

Bd²,

Ho³

et al. 2014

J. Phys.: Condens. Matter

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Abstract.A crossover from a non-Fermi liquid to a Fermi liquid phase in Yb 2 Ni 12 P 7 is observed by analyzing electrical resistivity ρ(T ), magnetic susceptibility χ(T ), specific heat C(T ), and thermoelectric power S(T ) measurements. The electronic contribution to specific heat, C e (T ), behaves as C e (T )/T ∼ − ln(T ) for 5 K < T < 15 K, which is consistent with non-Fermi liquid behavior. Below T ∼ 4 K, the upturn in C e (T )/T begins to saturate, suggesting that the system crosses over into a Fermi-liquid ground state. This is consistent with robust ρ(T )−ρ 0 = AT 2 behavior below T ∼ 4 K, with the power-law exponent becoming sub-quadratic for T > 4 K. A crossover between Fermiliquid and non-Fermi liquid behavior suggests that Yb 2 Ni 12 P 7 is in close proximity to a quantum critical point, in agreement with results from recent measurements of this compound under applied pressure.

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Physical properties ofYbXCu4(X=Ag,Au, Cd,

Cited by 152 publications

References 46 publications

Evolution of Technetium Speciation in Reducing Grout

Evolution of Technetium Speciation in Reducing Grout

Slow crossover inYbXCu4(X=Ag, Cd, In, Mg, Tl, Zn) intermediate-valence compounds

Crossover between Fermi liquid and non-Fermi liquid behavior in the non-centrosymmetric compound Yb₂Ni₁₂P₇

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Physical properties ofYbXCu4(X=Ag,Au, Cd,

Cited by 152 publications

References 46 publications

Evolution of Technetium Speciation in Reducing Grout

Evolution of Technetium Speciation in Reducing Grout

Slow crossover inYbXCu4(X=Ag, Cd, In, Mg, Tl, Zn) intermediate-valence compounds

Crossover between Fermi liquid and non-Fermi liquid behavior in the non-centrosymmetric compound Yb2Ni12P7

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Product

Resources

About

Crossover between Fermi liquid and non-Fermi liquid behavior in the non-centrosymmetric compound Yb₂Ni₁₂P₇