Samarium(III) fluoride ( Sm F₃) is a slightly

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

solid

fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...

. Conditions/substances to avoid are: open

flame A flame () is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction made in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density, they are then considered plasm ...

, moisture, strong

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

Preparation

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

\mathsf

Physical

At room temperature, samarium(III) fluoride has

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

structure with

space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

''Pnma'' – β-YF₃ type with

lattice constant A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has ...

s ''a'' = 666,9 pm, ''b'' = 705,9 pm, ''c'' = 440,5 pm. Above 495 °C, it has the

rhombohedral In geometry, a rhombohedron (also called a rhombic hexahedron or, inaccurately, a rhomboid) is a special case of a parallelepiped in which all six faces are congruent rhombus, rhombi. It can be used to define the rhombohedral lattice system, a Ho ...

LaF₃ structure (space group ''P3cl'') – with lattice constants ''a'' = 707, ''c'' = 724 pm.

References

{{Lanthanide halides Fluorides Lanthanide halides Samarium(III) compounds