Abstract

Lanthanide contraction of lanthanum and 14 lanthanides (Ln), leading to a decrease in R³⁺ ionic radii by ~15% (with respect to the smallest one) with an increase in the element atomic number Z, is a way to implement a close packing of F^1– ions in trifluorides of heavy 4f elements of the periodic table of elements. The efficiency of lanthanide (Ln) and actinide (An) contraction in the formation of inorganic fluoride crystals with a minimum unit-cell volume per fluorine ion (V_F) is estimated. For AnF₃ (An = Ac–Am), the V_F value decreases from ~20 to ~17.4 ų with an increase in Z from 89 to 95. The unavailability of heavy An makes this value final. The close packing of the fluorine ion in fluorides could not be obtained using the effects of lanthanide and actinide contraction and increase in the cation valence. Fluorides LnF₃ (structure type β-YF₃) from the end of the series from ErF₃ (15.86 ų) to LuF₃ (15.48 ų) are nearest to the anion close packing. The latter V_F value is minimum among all studied LnF₃ compounds and actinide fluorides (both simple and complex) and close to the saturation value. It corresponds to the estimated fluorine ionic radius of 1.246 Å.

中文翻译：

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镧和三氟化镧：镧系元素的收缩和氟离子的体积

摘要

镧和14镧系元素（Ln）的镧系元素收缩会导致R ³⁺离子半径随元素原子序数Z的增加而降低〜15％（相对于最小的），这是实现封闭的一种方法在元素周期表的重4 f元素的三氟化物中填充F ^1–离子。估计镧系元素（Ln）和act系元素（An）在形成无机氟化物晶体（每氟离子的单位晶胞体积最小）（V _F）时的收缩效率。对于一个˚F ₃（一种= AC-AM），所述V _˚F值从〜20到〜17.4埃降低³与增加Ž从89至95重的不可用性的使这个值最后。利用镧系元素和act系元素的收缩以及阳离子化合价的增加，无法获得氟离子在氟离子中的紧密堆积。氟化物LN ˚F ₃（结构型β-YF ₃）从系列从ERF的端部₃（15.86埃³至LUF）₃（15.48埃³）是最接近于阴离子紧密堆积。在所有研究的Ln F中，后一个V _F值最小_3种化合物和act系元素氟化物（简单和复杂）并接近饱和值。它对应于1.246Å的估计氟离子半径。