Ion specific effects on the structure of molten AF-ZrF systems (A = Li, Na, and K)

溶融AF-ZrF(A=Li, Na and K)系の構造におけるイオン種の効果

Pauvert, O.*; Salanne, M.*; Zanghi, D.*; Simon, C.*; Reguer, S.*; Thiaudire, D.*; 岡本 芳浩  ; 松浦 治明*; Bessada, C.*

Pauvert, O.*; Salanne, M.*; Zanghi, D.*; Simon, C.*; Reguer, S.*; Thiaudire, D.*; Okamoto, Yoshihiro; Matsuura, Haruaki*; Bessada, C.*

AF-ZrF system (A=Li, Na, K)混合系融体の構造を、EXAFS分光法と分子動力学(MD)計算法の組合せによって調べた。EXAFSの結果は、MD計算によって良好に再現された。計算では、融体中の7配位や6配位の構造の安定化の促進具合を評価した。Li, Na及びKの間の違いと、組成による違いを、系統的に調べた。MD計算からラマン分光スペクトルの導出も行った。また、配位構造がどの程度の時間保たれるかの評価も実施した。配位構造同士の相関については、Zr-Zr対の部分相関関数から評価した。

The structure of molten AF-ZrF system (A=Li, Na, K) is studied using EXAFS spectroscopy with molecular dynamics simulations. From the Zr solvation shell point of view, we observe a progressive stabilization of the 7-fold and then of the 6-fold coordinated complexes when passing from Li to Na and K as a "counterion". Particular attention is given to the systems consisting of 35 mol% of ZrF. At that particular composition, the ZrF complex predominates largely whatever the nature of the alkali. The calculated vibrational properties of this complex are in excellent agreement with a previous Raman spectroscopy experiment on molten KF-ZrF. The most important differences are observed for the lifetime of these octahedral units. On a larger scale, an intense first sharp diffraction peak is observed for the Zr-Zr partial structure factor, which can be attributed to the correlations between the octahedral units formed.