Cerium(III) fluoride (or cerium trifluoride), CeF
3, is an ionic compound of the rare earth metal
cerium
Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 ...
and
fluorine.
It appears as a mineral in the form of
fluocerite-(Ce) - a very rare mineral species related mainly to
pegmatites
A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic co ...
and rarely to
oxidation zones of some
polymetallic
In chemistry or mining, polymetal or polymetallic is a substance composed of a combination of different metals. When the substance contains only two metals the term '' bimetal'' (''bimetallic'') is sometimes preferred. A (or ') is an ore that ...
ore deposits. CeF
3 may be used as a
Faraday rotator
A Faraday rotator is a polarization rotator based on the Faraday effect, a magneto-optic effect involving transmission of light through a material when a longitudinal static magnetic field is present. The state of polarization (such as the axis o ...
material in the visible, near-infrared and mid-infrared spectral range.
Structure
The
crystal structure
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns ...
of cerium(III) fluoride is described as the
or
tysonite structure.
It contains
9-coordinate cerium ions that adopt an approximately
tricapped trigonal prismatic coordination geometry
The term coordination geometry is used in a number of related fields of chemistry and solid state chemistry/physics.
Molecules
The coordination geometry of an atom is the geometrical pattern formed by atoms around the central atom.
Inorganic coo ...
,
although it can be considered 11-coordinate if two more distant fluorides are considered part of the cerium coordination environment.
The three crystallographically independent fluoride ions are 3-coordinate and range in geometry from
trigonal planar to
pyramidal
A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilater ...
.
References
Cerium(III) compounds
Fluorides
Lanthanide halides
{{inorganic-compound-stub