Lanthanide Contraction in ILn/IF[sub.3] and Its Chemical and Structural Consequences: Part 1: Location of YF[sub.3] in the ILn/IF[sub.3] Series According to Its Chemical and Structural Characteristics

• Published in: International journal of molecular sciences 2023-11, Vol.24 (23)
• Main Authors: Sobolev, Boris P, Sulyanova, Elena A
• Format: Article
• Language: English
• Subjects: Rare earth metals
• ISSN: 1422-0067
• DOI: 10.3390/ijms242317013

A lanthanide contraction(LC) of 14 lanthanides (Ln) from [sub.58]Ce to [sub.71]Lu consists of the interaction of Ln nucleus with 4f-electrons. Rare earth elements (REEs—R) include Sc, Y, La, and 14 Ln. They are located in 4–6th periods of the subgroup of group III. The electronic structure divides R into short (d- Sc, Y, La) and long (14 f-elements Ce-Lu) homologous series. The most important chemical consequence of LC is the creation of a new conglomerate of 16 RF[sub.3] by mixing fluorides of d- (Y, La) and f-elements. This determines the location of YF[sub.3] among LnF[sub.3]. The location of YF[sub.3] depends on the structural (formula volumes—Vform) and thermochemical (temperatures and heats of phase transformations, phase diagrams) properties. The location of YF[sub.3] between HoF[sub.3] and ErF[sub.3] was determined by V[sub.form] at a standard pressure (Pst) and temperature (Tst). The location of YF[sub.3] according to heats of phase transformations ΔHfus and ΔHtrans is in a dimorphic structural subgroup (SSGr) D (Ln = Er-Lu), but without the exact “pseudo Z[sub.Y]”. According to the temperatures of phase transformations (T[sub.trans]) in LnF[sub.3] (Ln = Dy-Lu), YF[sub.3] is located in the SSGr D between ErF[sub.3] and TmF[sub.3]. The ErF[sub.3]-YF[sub.3] and YF[sub.3]-TmF[sub.3] phase diagrams show it to be between ErF[sub.3] and TmF[sub.3]. The crystals of five β-LnF[sub.3] (Ln = Ho-Lu) and β-YF[sub.3] were obtained in identical conditions and their crystal structures were studied. V[sub.form] (at P[sub.st] and T[sub.st]) with “pseudo” atomic numberZ[sub.Y] = 67.42 was calculated from the unit cell parameters, which were defined with ±5 × 10[sup.−4] Å accuracy. It determines the location of YF[sub.3] between HoF[sub.3] and ErF[sub.3].