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Journal Articles

A Thermodynamic model for the solubility of HfO$$_{2}$$(am) in the aqueous K$$^{+}$$ - HCO$$_{3}$$$$^{-}$$ - CO$$_{3}$$$$^{2-}$$ - OH$$^{-}$$ - H$$_{2}$$O system

Rai, D.*; Kitamura, Akira; Rosso, K.*

Radiochimica Acta, 105(8), p.637 - 647, 2017/08

 Times Cited Count:1 Percentile:15.39(Chemistry, Inorganic & Nuclear)

Solubility of HfO$$_{2}$$(am) was determined as a function of KHCO$$_{3}$$ concentrations ranging from 0.001 mol.kg$$^{-1}$$ to 0.1 mol.kg$$^{-1}$$. The solubility of HfO$$_{2}$$(am) increased dramatically with the increase in KHCO$$_{3}$$ concentrations, indicating that Hf(IV) makes strong complexes with carbonate. Thermodynamic equilibrium constants for the formation of Hf-carbonate complexes were determined using both the Pitzer and SIT models. The dramatic increase in Hf concentrations with the increase in KHCO$$_{3}$$ concentrations can best be described by the formation of Hf(OH-)$$_{2}$$(CO$$_{3}$$)$$_{2}$$$$^{2-}$$ and Hf(CO$$_{3}$$)$$_{5}$$$$^{6-}$$. The log$$_{10}$$ K$$^{0}$$ values for the reactions [Hf$$^{4+}$$ + 2 CO$$_{3}$$$$^{2-}$$ +2 OH$$^{-}$$ $$leftrightarrow $$ Hf(OH)$$_{2}$$(CO$$_{3}$$)$$_{2}$$$$^{2-}$$] and [Hf$$^{4+}$$ + 5 CO$$_{3}$$$$^{2-}$$ $$leftrightarrow $$ Hf(CO$$_{3}$$)$$_{5}$$$$^{6-}$$], based on the SIT model, were determined to be 44.53 $$pm$$ 0.46 and 41.53 $$pm$$ 0.46, respectively.

Journal Articles

Issues concerning the determination of solubility products of sparingly soluble crystalline solids; Solubility of HfO$$_{2}$$(cr)

Rai, D.*; Kitamura, Akira; Rosso, K. M.*; Sasaki, Takayuki*; Kobayashi, Taishi*

Radiochimica Acta, 104(8), p.583 - 592, 2016/08

 Times Cited Count:4 Percentile:45.9(Chemistry, Inorganic & Nuclear)

Solubility studies were conducted with HfO$$_{2}$$(cr) solid as a function of acid concentrations. These studies involved (1) using two different amounts of the solid phase, (2) acid washing the bulk solid phase, (3) preheating the solid phase to 1400 $$^{circ}$$C, and (4) heating amorphous HfO$$_{2}$$(am) suspensions to 90 $$^{circ}$$C to ascertain whether the HfO$$_{2}$$(am) converts to HfO$$_{2}$$(cr) and to determine the solubility from the oversaturation direction. Based on the results of these treatments it is concluded that the HfO$$_{2}$$(cr) contains a small fraction of less crystalline, but not amorphous, material [HfO$$_{2}$$(lcr)] and this, rather than the HfO$$_{2}$$(cr), is the solubility-controlling phase in the range of experimental variables investigated in this study. The solubility data are interpreted using both the Pitzer and SIT models. The log$$_{10}$$ of the solubility product of HfO$$_{2}$$(cr) is estimated. The observation of a small fraction of less crystalline higher solubility material is consistent with the general picture that mineral surfaces are often structurally and/or imperfect leading to a higher solubility than the bulk crystalline solid. This study stresses the urgent need, during interpretation of solubility data, of taking precautions to make certain that the observed solubility behavior for sparingly-soluble solids is assigned to the proper solid phase.

Journal Articles

Equilibrium pressures of hydrogen and deuterium dissolved in titanium,zirconium and hafnium at low concentrations

Journal of Nuclear Materials, 136, p.1 - 5, 1985/00

 Times Cited Count:29 Percentile:93.65(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Determination of hafnium in zirconium and its alloys by a stable isotope dilution; Neutron activation analysis

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Anal. Chem., 55(13), p.2059 - 2062, 1983/00

 Times Cited Count:13 Percentile:62.47(Chemistry, Analytical)

no abstracts in English

Journal Articles

The Separation of zirconium and hafnium by tributyl phosphate-celite reversed-phase partition chromatography

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Bulletin of the Chemical Society of Japan, 39(10), p.2183 - 2187, 1966/00

 Times Cited Count:11

no abstracts in English

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