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<p>Spontaneously cooled samples of the systems (LiF–CaF<sub>2</sub>)<sub>eut</sub>–<i>n</i>LnF<sub>3</sub> (Ln = Nd, Sm, Gd; <i>n</i> = 0.01–0.4 for Nd and Sm, and 0.01–0.3 for Gd) have been reexamined using X-ray powder diffraction to clarify the composition of previously unidentified phases. For these systems, apart from the crystallisation of LiF, NdF<sub>3</sub> (Ln = Nd; <i>n</i> &gt; 0.01), Ca<sub><i>y</i></sub>Sm<sub>1−<i>y</i></sub>F<sub>3−<i>y</i></sub> (Ln = Sm; <i>n</i> &gt; 0.01), or LiGdF<sub>4</sub> (Ln = Gd; <i>n</i> ≥ 0.03), the formation of cubic phases Ca<sub>1−<i>x</i></sub>Ln<sub><i>x</i></sub>F<sub>2+<i>x</i></sub> (<i>x</i> ≈ 0.2–0.35 for Nd, 0.16–0.39 for Sm, and 0.17–0.32 for Gd) with a fluorite-related structure is observed. Initial compositions of these cubic phases were calculated based on the determined cell parameters and refined using the CeH<sub>3</sub> crystal structure model. Phases Ca<sub>1−<i>x</i></sub>Ln<sub><i>x</i></sub>F<sub>2+<i>x</i></sub> (fluorite-related structure) and Ca<sub><i>y</i></sub>Sm<sub>1−<i>y</i></sub>F<sub>3−<i>y</i></sub> (tysonite-type structure) are forming due to the isomorphous heterovalent substitution and known to be characterised by numerous defects in their crystal structures. Assuming that the formation of nonstoichiometric phases Ca<sub>1−<i>x</i></sub>Ln<sub><i>x</i></sub>F<sub>2+<i>x</i></sub> and Ca<sub><i>y</i></sub>Sm<sub>1−<i>y</i></sub>F<sub>3−<i>y</i></sub> leads to enhanced conductivity, <i>ac</i> conductivity measurements were performed at room temperature for (LiF–CaF<sub>2</sub>)<sub>eut</sub>–<i>n</i>LnF<sub>3</sub> samples (<i>n</i> = 0.15, 0.3) in the frequency range of 1&#xa0;kHz–1&#xa0;MHz to evaluate their presence and effect.</p> Graphical abstract <p></p>

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Components interaction in the systems (LiF–CaF2)eut–nLnF3 (Ln = Nd, Sm, Gd)

  • 期刊论文

  • 发表日期：

    2026年3月18日

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  • Oksana Matselko,
  • Zuzana Netriová,
  • Jarmila Mlynáriková,
  • Blanka Kubíková,
  • Jaroslav Rusnák,
  • Miroslav Boča

摘要

Spontaneously cooled samples of the systems (LiF–CaF2)eut–nLnF3 (Ln = Nd, Sm, Gd; n = 0.01–0.4 for Nd and Sm, and 0.01–0.3 for Gd) have been reexamined using X-ray powder diffraction to clarify the composition of previously unidentified phases. For these systems, apart from the crystallisation of LiF, NdF3 (Ln = Nd; n > 0.01), CaySm1−yF3−y (Ln = Sm; n > 0.01), or LiGdF4 (Ln = Gd; n ≥ 0.03), the formation of cubic phases Ca1−xLnxF2+x (x ≈ 0.2–0.35 for Nd, 0.16–0.39 for Sm, and 0.17–0.32 for Gd) with a fluorite-related structure is observed. Initial compositions of these cubic phases were calculated based on the determined cell parameters and refined using the CeH3 crystal structure model. Phases Ca1−xLnxF2+x (fluorite-related structure) and CaySm1−yF3−y (tysonite-type structure) are forming due to the isomorphous heterovalent substitution and known to be characterised by numerous defects in their crystal structures. Assuming that the formation of nonstoichiometric phases Ca1−xLnxF2+x and CaySm1−yF3−y leads to enhanced conductivity, ac conductivity measurements were performed at room temperature for (LiF–CaF2)eut–nLnF3 samples (n = 0.15, 0.3) in the frequency range of 1 kHz–1 MHz to evaluate their presence and effect.

Graphical abstract