 | |
| Names | |
|---|---|
| Other names Platinum--uranium (3/1) | |
| Identifiers | |
3D model (JSmol) | |
PubChem CID | |
CompTox Dashboard (EPA) | |
| |
| |
| Properties | |
| UPt3 | |
| Molar mass | 823.3 g/mol [1] |
| Density | 19.3 g/cm3 |
| Melting point | 1700°C [2] |
| Structure | |
| see text | |
| 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). | |
UPt3 is an inorganic binary intermetallic crystalline compound of platinum and uranium. [1]
It can be syntetized in the following ways: [3]
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]
Unconventional superconductors are materials that display superconductivity which does not conform to conventional BCS theory or its extensions.
In physics, the Kondo effect describes the scattering of conduction electrons in a metal due to magnetic impurities, resulting in a characteristic change i.e. a minimum in electrical resistivity with temperature. The cause of the effect was first explained by Jun Kondo, who applied third-order perturbation theory to the problem to account for scattering of s-orbital conduction electrons off d-orbital electrons localized at impurities. Kondo's calculation predicted that the scattering rate and the resulting part of the resistivity should increase logarithmically as the temperature approaches 0 K. Experiments in the 1960s by Myriam Sarachik at Bell Laboratories provided the first data that confirmed the Kondo effect. Extended to a lattice of magnetic impurities, the Kondo effect likely explains the formation of heavy fermions and Kondo insulators in intermetallic compounds, especially those involving rare earth elements such as cerium, praseodymium, and ytterbium, and actinide elements such as uranium. The Kondo effect has also been observed in quantum dot systems.
In Materials Science, heavy fermion materials are a specific type of intermetallic compound, containing elements with 4f or 5f electrons in unfilled electron bands. Electrons are one type of fermion, and when they are found in such materials, they are sometimes referred to as heavy electrons. Heavy fermion materials have a low-temperature specific heat whose linear term is up to 1000 times larger than the value expected from the free electron model. The properties of the heavy fermion compounds often derive from the partly filled f-orbitals of rare-earth or actinide ions, which behave like localized magnetic moments. The name "heavy fermion" comes from the fact that the fermion behaves as if it has an effective mass greater than its rest mass. In the case of electrons, below a characteristic temperature (typically 10 K), the conduction electrons in these metallic compounds behave as if they had an effective mass up to 1000 times the free particle mass. This large effective mass is also reflected in a large contribution to the resistivity from electron-electron scattering via the Kadowaki–Woods ratio. Heavy fermion behavior has been found in a broad variety of states including metallic, superconducting, insulating and magnetic states. Characteristic examples are CeCu6, CeAl3, CeCu2Si2, YbAl3, UBe13 and UPt3.
Organoplatinum chemistry is the chemistry of organometallic compounds containing a carbon to platinum chemical bond, and the study of platinum as a catalyst in organic reactions. Organoplatinum compounds exist in oxidation state 0 to IV, with oxidation state II most abundant. The general order in bond strength is Pt-C (sp) > Pt-O > Pt-N > Pt-C (sp3). Organoplatinum and organopalladium chemistry are similar, but organoplatinum compounds are more stable and therefore less useful as catalysts.
Heavy fermion superconductors are a type of unconventional superconductor.
UPd2Al3 is a heavy-fermion superconductor with a hexagonal crystal structure and critical temperature Tc=2.0K that was discovered in 1991. Furthermore, UPd2Al3 orders antiferromagnetically at TN=14K, and UPd2Al3 thus features the unusual behavior that this material, at temperatures below 2K, is simultaneously superconducting and magnetically ordered. Later experiments demonstrated that superconductivity in UPd2Al3 is magnetically mediated, and UPd2Al3 therefore serves as a prime example for non-phonon-mediated superconductors.
YbBiPt is an intermetallic material which at low temperatures exhibits an extremely high value of specific heat, which is a characteristic of heavy-fermion behavior. YbBiPt has a noncentrosymmetric cubic crystal structure; in particular it belongs to the ternary half-Heusler compounds.
Yttrium oxyfluoride is an inorganic chemical compound with the formula YOF. Under normal conditions, the compound is a colorless solid.
Beryllium oxalate is an inorganic compound, a salt of beryllium metal and oxalic acid with the chemical formula C
2BeO
4. It forms colorless crystals, dissolves in water, and also forms crystalline hydrates. The compound is used to prepare ultra-pure beryllium oxide by thermal decomposition.
Lithium oxalate is an inorganic compound, a salt of lithium metal and oxalic acid with the chemical formula C
2Li
2O
4. Lithium oxalate is soluble in water and converts to the oxide when heated.
Copper oxalate is an inorganic compound, a salt of copper metal and oxalic acid with the chemical formula CuC
2O
4. The compound is practically insoluble in water, alcohol, ether, and acetic acid but soluble in ammonium hydroxide. Copper oxalate forms a hydrate, which forms acid-blue crystals.
Praseodymium(IV) fluoride (also praseodymium tetrafluoride) is a binary inorganic compound, a highly oxidised metal salt of praseodymium and fluoride with the chemical formula PrF4.
Manganese oxalate is a chemical compound, a salt of manganese and oxalic acid with the chemical formula MnC
2O
4. The compound creates light pink crystals, does not dissolve in water, and forms crystalline hydrates. It occurs naturally as the mineral Lindbergite.
Neptunium (IV) oxalate is an inorganic compound, a salt of neptunium and oxalic acid with the chemical formula Np(C2O4)2. The compound is slightly soluble in water, forms crystalline hydrates—green crystals.
Platinum-samarium is a binary inorganic compound of platinum and samarium with the chemical formula PtSm. This intermetallic compound forms crystals.
Plutonium silicide is a binary inorganic compound of plutonium and silicon with the chemical formula PuSi. The compound forms gray crystals.
Lutetium(III) nitrate is an inorganic compound, a salt of lutetium and nitric acid with the chemical formula Lu(NO3)3. The compound forms colorless crystals, dissolves in water, and also forms crystalline hydrates. The compound is poisonous.
Polonium tetranitrate is an inorganic compound, a salt of polonium and nitric acid with the chemical formula Po(NO3)4. The compound is radioactive, forms white crystals.
Protactinium(IV) bromide is an inorganic compound. It is an actinide halide, composed of protactinium and bromine. It is radioactive, and has the chemical formula of PaBr4. It may be due to the brown color of bromine that causes the appearance of protactinium(IV) bromide to be brown crystals. Its crystal structure is tetragonal. Protactinium(IV) bromide is sublimed in a vacuum at 400 °C. The protactinium(IV) halide closest in structure to protactinium(IV) bromide is protactinium(IV) chloride.
Praseodymium antimonide is a binary inorganic compound of praseodymium and antimony with the formula PrSb.
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