UPt3

UPt₃ is an inorganic binary intermetallic crystalline compound of platinum and uranium.^[1]

Uranium platinum

Names
Other names Platinum--uranium (3/1)
Identifiers
CAS Number	12311-92-1
3D model (JSmol)	Interactive image
ChemSpider	57534709
PubChem CID	71354824
CompTox Dashboard (EPA)	DTXSID90779273
InChI InChI=1S/3Pt.U Key: YYBWTXHBZRZQRM-UHFFFAOYSA-N
SMILES [Pt].[Pt].[Pt].[U]
Properties
Chemical formula	UPt3
Molar mass	823.3 g/mol[1]
Density	19.3 g/cm3
Melting point	1700°C[2]
Structure
Crystal structure	see text
Space group	P63/mmc
Thermochemistry
Std molar entropy (S⦵298)	−111 J·mol−1·K−1[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Production

It can be synthesised in the following ways:^[3]

• as an intermetallic compound, by direct fusion of pure components according to stoichiometric calculations:

${\displaystyle {\mathsf {3Pt+U\ {\xrightarrow {1700^{o}C}}\ UPt_{3}}}}$

• by reduction of uranium dioxide with hydrogen in the presence of platinum:

${\displaystyle {\mathsf {UO_{2}+2H_{2}+3Pt\ {\xrightarrow {1700^{o}C}}\ UPt_{3}+2H_{2}O}}}$

Physical properties

UPt₃ forms crystals of hexagonal symmetry (some studies hypothesize a trigonal structure instead^[4]), space group P6₃/mmc,^[5] cell parameters a = 0.5766 nm and c = 0.4898 nm (c should be understood as distance from planes), with a structure similar to nisnite (Ni₃Sn) and MgCd₃.^[6][7]

The compound congruently melts at 1700 °C.^[2] The enthalpy of formation of the compound is -111 kJ/mol.^[3]

At temperatures below 1 K it becomes superconducting, thought to be due to the presence of heavy fermions (the uranium atoms).^[8][9]