Scandium fluoride

Names
IUPAC name

Scandium(III) fluoride

Other names

Scandium trifluoride

Identifiers

CAS Number

* 13709-47-2 N

3D model (JSmol)

* Interactive image

EC Number |

* 237-555-4

PubChem CID

* 83678

RTECS number |

* VQ8930000

InChI

* InChI=1S/3FH.Sc/h3*1H;/q;;;+3/p-3

SMILES

* F[Sc](F)F

Properties

Chemical formula

| ScF3
Molar mass | 101.95112 g/mol
Appearance  | bright white powder
Density | 2.53 g/cm3
Melting point |  1,552 °C (2,826 °F; 1,825 K)[2]
Boiling point |  1,607 °C (2,925 °F; 1,880 K)[2]

Solubility product (Ksp)

| 5.81×10−24[1]
Structure

Crystal structure

| Cubic, Pm3m

Space group

| Pm3m, No. 221
Hazards
NFPA 704 (fire diamond)  |

Related compounds

Other anions

| Scandium(III) chloride
Scandium(III) bromide
Scandium(III) iodide

Other cations

| Yttrium(III) fluoride
Lutetium(III) fluoride

Related compounds

| Scandium(III) nitrate

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is YN ?)
Infobox references

Scandium(III) fluoride, ScF3, is an ionic compound. This salt is slightly soluble in water but dissolves in the presence of excess fluoride to form the ScF63− anion.[2]

## Production

ScF3 can be produced by reacting scandium and fluorine.[3] It is also formed during the extraction from the ore thortveitite by the reaction of Sc2O3 with ammonium bifluoride at high temperature:[4]

Sc2O3 \+ 6 NH4HF2 → 2 ScF3 \+ 6 NH4F + 3 H2O

The resulting mixture contains a number of metal fluorides and this is reduced by reaction with calcium metal at high temperature.[4] Further purification steps are required to produce usable metallic scandium.[4]

## Properties

Scandium trifluoride exhibits the unusual property of negative thermal expansion, meaning it shrinks when heated. This phenomenon is explained by the quartic oscillation of the fluoride ions. The energy stored in the bending strain of the fluoride ion is proportional to the fourth power of the displacement angle, unlike most other materials where it is proportional to the square of the displacement. A fluorine atom is bound to two scandium atoms, and as temperature increases the fluorine oscillates more perpendicularly to its bonds. This motion draws the scandium atoms together throughout the bulk material, which contracts.[5] ScF3 exhibits this property from at least 10 K to 1100 K above which it shows the normal positive thermal expansion; furthermore, the material has cubic symmetry over this entire temperature range, and up to at least 1600 K at ambient pressure. The negative thermal expansion at very low temperatures is quite strong (coefficient of thermal expansion around -14 ppm/K between 60 and 110 K).[6]

At ambient pressures scandium trifluoride adopts the cubic crystal system, using the perovskite structure with one metal position vacant.[7] The unit cell dimension is 4.01 Å.[7] Under pressure scandium trifluoride also forms different crystal structures with rhombohedral, and above 3 GPa tetrahedral.[7]

## References

1. ↑ John Rumble (June 18, 2018) (in English). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–189. ISBN 978-1138561632.
2. ↑ 2.0 2.1 2.2 Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier, ISBN 0-12-352651-5.
3. ↑ S.A.Cotton, Scandium, Yttrium and the Lanthanides: Inorganic and Coordination Chemistry, Encyclopedia of Inorganic Chemistry, 1994, John Wiley & Sons, ISBN 0-471-93620-0.
4. ↑ 4.0 4.1 4.2 Pradyot Patnaik, 2003, Handbook of Inorganic Chemicals, McGraw-Hill Professional, ISBN 0-07-049439-8.
5. ↑ Woo, Marcus (7 November 2011). "An incredible shrinking material: Engineers reveal how scandium trifluoride contracts with heat". Physorg. http://www.physorg.com/news/2011-11-incredible-material-reveal-scandium-trifluoride.html.
6. ↑ Greve, Benjamin K.; Kenneth L. Martin; Peter L. Lee; Peter J. Chupas; Karena W. Chapman; Angus P. Wilkinson (19 October 2010). "Pronounced Negative Thermal Expansion from a Simple Structure: Cubic ScF3". Journal of the American Chemical Society 132 (44): 15496–15498. doi:10.1021/ja106711v. PMID 20958035.
7. ↑ 7.0 7.1 7.2 Aleksandrov, K. S.; V. N. Voronov; A. N. Vtyurin; A. S. Krylov; M. S. Molokeev; M. S. Pavlovskiĭ; S. V. Goryaĭnov; A. Yu. Likhacheva et al. (2009). "Pressure-induced phase transition in the cubic ScF3 crystal". Physics of the Solid State 51 (4): 810–816. doi:10.1134/S1063783409040295. ISSN 1063-7834. Bibcode: 2009PhSS...51..810A.

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Scandium compounds

* ScB12
* ScBr3
* ScCl3
* ScF3
* ScH3
* ScI3
* ScN
* Sc(NO3)3
* Sc2O3
* ScS
* Sc2S3
* Sc2(SO4)3
* Sc(SO3CF3)3
* ScB2
* Sc(ClO4)3
* ScSb
* Sc2Te3
* Sc(C5H5)3
* Sc(C9H13)3
* Sc(OH)3
* Sc(OCH(CH3)2)3

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Salts and covalent derivatives of the fluoride ion

HF |  |  |  | He

|
|
|
|

LiF | BeF2 | BF
BF3
B2F4 | CF4
other compounds | NF3
FN3
N2F2
N2F4
NF5§  | F2O
F2O2
other compounds | F2 | Ne
NaF | MgF2 | AlF
AlF3 | SiF4 | P2F4
PF3
PF5 | S2F2
SF2
SF4
SF6 | ClF
ClF3
ClF5 | Ar
KF | CaF
CaF2 | ScF3 | TiF2
TiF3
TiF4 | VF2
VF3
VF4
VF5 | CrF2
CrF3
CrF4
CrF5
CrF6§  | MnF2 | FeF2
FeF3 | CoF2
CoF3 | NiF2 | CuF
CuF2 | ZnF2 | GaF2
GaF3 | GeF2
GeF4 | AsF3
AsF5 | Se2F2
SeF4
SeF6 | BrF
BrF3
BrF5 | KrF2
RbF | SrF
SrF2 | YF3 | ZrF3
ZrF4 | NbF4
NbF5 | MoF2
MoF3
MoF4
MoF5
MoF6 | TcF4
TcF6 | RuF3
RuF5
RuF6 | RhF3
RhF5
RhF6 | PdF2 | AgF | CdF2 | InF
InF2
InF3 | SnF2
SnF4 | SbF3
SbF5 | Te3F2
TeF4
TeF6 | IF
IF3</br>IF5</br>IF7 | XeF2
XeF4
XeF6
CsF | BaF2 |  | HfF4 | TaF5 | WF2
WF3
WF4
WF5
WF6 | Re3F9
ReF4
ReF5
ReF6
ReF7 | OsF4
OsF5
OsF6 | IrF2
IrF3
IrF4
IrF5
IrF6 | PtF2
PtF4
PtF5
PtF6 | AuF
AuF3
Au2F10
AuF5•F2 | Hg2F2
HgF2
HgF4 | TlF | PbF2
PbF4 | BiF3
BiF5 | PoF2
PoF4
PoF6 | AtF  | RnF2
FrF | RaF2 |  | Rf  | Db  | Sg  | Bh  | Hs  | Mt  | Ds  | Rg  | Cn  | Nh  | Fl  | Mc  | Lv  | Ts  | Og
| ↓  |  |
LaF3 | CeF3
CeF4 | PrF3 | NdF2,
NdF3 | PmF3 | SmF2,
SmF3 | EuF2,
EuF3 | GdF3 | TbF3 | DyF2,
DyF3 | HoF3 | ErF3 | TmF2
TmF3 | YbF2
YbF3 | LuF3
AcF3 | ThF4 | PaF5 | UF3
UF4
UF5
UF6 | NpF4
NpF6 | PuF3
PuF6 | AmF2
AmF3 | CmF3 | BkF3 | CfF3 | EsF3 | Fm  | Md  | No  | LrF3

§ means the substance has not been made.

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