TY - JOUR
T1 - The Ionic Strength Dependence of Rare Earth and Yttrium Fluoride Complexation at 25°C
AU - Luo, Yu-Ran
AU - Byrne, Robert H.
PY - 2000/1/1
Y1 - 2000/1/1
N2 - Formation constants for the complexation of yttrium and rare earth elements(YREE) by fluoride ions have been measured at 25°C. The ionic strength (μ)dependence of YREE formation constants in perchlorate solution for ionicstrengths between 0 and 6 molar can be expressed aslog F β 1 (M, μ) =log F β 1 o (M) −3.066 μ 0.5 /(1 + 1.769 μ 0.5 )+ 0.1645 μwhere log F β 1 o (M) represents MF 2+ formation constants at zero ionic strength.The log F β 1 o (M) results obtained inthis work are: Y(4.46), La(3.62), Ce(3.86),Pr(3.84), Nd(3.82), Sm(4.15), Eu(4.27), Gd(4.24), Tb(4.37), Dy(4.39), Ho(4.28),Er(4.27), Tm(4.29), Yb(4.39), and Lu(4.25). The relative magnitudes of YREEformation constants are independent of ionic strength. The pattern oflog F β 1 (M,μ),formation constants obtained in this work [relative magnitudes oflog F β 1 o (M)],exhibits a shallow minimum between Dy and Yb. In contrast to the smoothpattern of stability constants expected if fluoride were to interact with bare ions(with monotonically decreasing crystal radii between La and Lu), theinteractionof F − with YREEs, which have extensive hydration spheres[M(H 2 O) 8–9 3+ ] resultsin a relatively complex pattern of lanthanide stability constants. The fluoridecomplexation behavior of yttrium differs distinctly from the behavior of any rareearth. Although the crystal radius of Y3;pl is approximately equalto that of Ho 3+ ,differences in the covalence/ionicity of Y 3+ relative to therare earths leads to aYF 2+ stability constant that exceeds that of any rare earthelement (REE).
AB - Formation constants for the complexation of yttrium and rare earth elements(YREE) by fluoride ions have been measured at 25°C. The ionic strength (μ)dependence of YREE formation constants in perchlorate solution for ionicstrengths between 0 and 6 molar can be expressed aslog F β 1 (M, μ) =log F β 1 o (M) −3.066 μ 0.5 /(1 + 1.769 μ 0.5 )+ 0.1645 μwhere log F β 1 o (M) represents MF 2+ formation constants at zero ionic strength.The log F β 1 o (M) results obtained inthis work are: Y(4.46), La(3.62), Ce(3.86),Pr(3.84), Nd(3.82), Sm(4.15), Eu(4.27), Gd(4.24), Tb(4.37), Dy(4.39), Ho(4.28),Er(4.27), Tm(4.29), Yb(4.39), and Lu(4.25). The relative magnitudes of YREEformation constants are independent of ionic strength. The pattern oflog F β 1 (M,μ),formation constants obtained in this work [relative magnitudes oflog F β 1 o (M)],exhibits a shallow minimum between Dy and Yb. In contrast to the smoothpattern of stability constants expected if fluoride were to interact with bare ions(with monotonically decreasing crystal radii between La and Lu), theinteractionof F − with YREEs, which have extensive hydration spheres[M(H 2 O) 8–9 3+ ] resultsin a relatively complex pattern of lanthanide stability constants. The fluoridecomplexation behavior of yttrium differs distinctly from the behavior of any rareearth. Although the crystal radius of Y3;pl is approximately equalto that of Ho 3+ ,differences in the covalence/ionicity of Y 3+ relative to therare earths leads to aYF 2+ stability constant that exceeds that of any rare earthelement (REE).
KW - Rare earth elements
KW - fluoride complexation
KW - stability constants
KW - sodium perchlorate
KW - ionic strength
KW - lanthanide
KW - yttrium
UR - https://digitalcommons.usf.edu/msc_facpub/1727
UR - https://doi.org/10.1023/A:1005186932126
U2 - 10.1023/A:1005186932126
DO - 10.1023/A:1005186932126
M3 - Article
VL - 29
JO - Journal of Solution Chemistry
JF - Journal of Solution Chemistry
ER -