Samarium(III) fluoride

Samarium(III) fluoride (SmF₃) is a slightly hygroscopic solid fluoride. Conditions/substances to avoid are: open flame, moisture, strong acids.

Preparation

Samarium(III) fluoride can be obtained by reacting SmCl₃ or Sm₂(CO₃)₃ with 40% hydrofluoric acid:

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Samarium(III) fluoride can also be produced by hydrothermal reaction of samarium nitrate and sodium fluroborate at 200 °C.

Properties

Chemical

Samarium(III) fluoride reacts with some reducing agents at high temperatures to obtain samarium(II) fluoride:

$\mathsf{4}\mathsf{S}\mathsf{m}{\mathsf{F}}_{\mathsf{3}}\mathsf{+}\mathsf{C}\stackrel{2000^{o}C}{\to }\mathsf{4}\mathsf{S}\mathsf{m}{\mathsf{F}}_{\mathsf{2}}\mathsf{+}\mathsf{C}{\mathsf{F}}_{\mathsf{4}}$

$\mathsf{2}\mathsf{S}\mathsf{m}{\mathsf{F}}_{\mathsf{3}}\mathsf{+}\mathsf{S}\mathsf{m}\stackrel{1800^{o}C}{\to }\mathsf{3}\mathsf{S}\mathsf{m}{\mathsf{F}}_{\mathsf{2}}$

Physical

At room temperature, samarium(III) fluoride has orthorhombic structure with space group Pnma – β-YF₃ type with lattice constants a = 666,9 pm, b = 705,9 pm, c = 440,5 pm. Above 495 °C, it has the rhombohedral LaF₃ structure (space group P3cl) – with lattice constants a = 707, c = 724 pm.