Erbium antimonide
Chemical compound
From Wikipedia, the free encyclopedia
Erbium antimonide is an inorganic compound of erbium and antimony with the chemical formula ErSb. It is a rare-earth monoantimonide that crystallizes in the cubic rock salt structure and is a semimetal. At low temperature it orders antiferromagnetically.[1]
| Names | |
|---|---|
| Other names
Erbium monoantimonide | |
| Identifiers | |
| EC Number |
|
PubChem CID |
|
| Properties | |
| ErSb | |
| Molar mass | 289.02 g/mol |
| Density | 8.432 g/cm3 (calculated) |
| Structure | |
| Cubic, rock-salt type | |
| Fm3m, No. 225 | |
a = 0.6106 nm | |
Formula units (Z) |
4 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Preparation
Bulk ErSb can be prepared by direct reaction of erbium and antimony:
- Er + Sb → ErSb
Erbium–antimony alloys have been synthesized by reacting the elements in evacuated silica tubes at about 600 °C for several days, followed by high-temperature homogenization.[2]
More recently, single-phase ErSb has been prepared by induction melting high-purity erbium and antimony, followed by annealing at 800 °C for five days.[1]
Properties
Crystal structure
ErSb crystallizes in the cubic crystal system with the rock-salt structure, space group Fm3m (No. 225), with four formula units per unit cell,[3] with a lattice parameter of a = 6.106 Å. Er occupies the (0,0,0) position and Sb the (1⁄2,1⁄2,1⁄2) position. The calculated density from this cell is 8.432 g/cm3.[3]
The compound melts congruently at about 2040 °C.[2]
Electronic properties
ErSb is a semimetal. Its electronic structure contains both electron and hole pockets at the Fermi level, with strongly localized Er 4f states and more dispersive Er 5d- and Sb 5p-derived bands.[4]
Calculations place hole pockets near the Γ point and an electron pocket near X, producing the semimetallic band overlap.[4]
Scanning-tunnelling spectroscopy on nanoscale ErSb inclusions likewise finds no discernible band gap, even for small nanoparticles for which quantum-confinement models had predicted a semiconductor transition.[5]
Magnetic properties
ErSb is antiferromagnetic at low temperature. Recent magnetic measurements give a Néel temperature of approximately 3.7 K.[1]
Older pressure-dependent measurements also identified ErSb as an antiferromagnetic member of the rare-earth monoantimonide series.[6]
The magnetic ordering is coupled to the crystal lattice. Elastic and thermal-expansion measurements show a structural anomaly accompanying the magnetic transition, indicating substantial magnetoelastic coupling.[7]
Applied magnetic fields produce first-order field-induced magnetic transitions. ErSb consequently exhibits both conventional and inverse magnetocaloric effects at temperatures close to its antiferromagnetic transition.[1] For a field change of 0–7 T, a maximum magnetic entropy change of about 20.8 J kg−1 K−1 and a refrigerant capacity of about 214 J kg−1 were reported.[1]
Nanostructures
ErSb can be grown by molecular-beam epitaxy as nanostructures embedded in gallium antimonide. Depending on erbium concentration and growth conditions, the inclusions can form approximately spherical nanoparticles, elongated nanorods or nanowires.[8]
The morphology evolves systematically with Er concentration, while the nanostructures retain semimetallic electrical behavior.[5][8] Their shape-dependent response from terahertz through optical frequencies has also led to investigation of ErSb/GaSb composites as plasmonic materials.[8]