Family of Mo₄Ga₂₁-Based Superconductors

Abstract

Endohedral cluster superconductors are an emerging field, where simple electron counting rules govern the phase stability and transition temperature. Nontrivial microscopic properties of the superconducting state, including strong electron–phonon coupling and multigap superconductivity, raise fundamental interest in studying these materials. Herein, Mo4Ga20.38(1)S0.62(1), Mo4Ga20Se, Mo4Ga20Te, and Mo4Ga20Sb endohedral cluster compounds were synthesized in the form of bulk polycrystalline samples and single crystals. Together with the recently reported Mo4Ga21–x–δSn x , these compounds belong to the new Mo4Ga21 structure type with notable functionality: all the discovered representatives show superconducting properties. The observed critical temperatures of 5.1, 3.3, 4.6, and 6.6 K for the S-, Se-, Te-, and Sb-containing compounds, respectively, correlate well with the experimental values of the Sommerfeld coefficient. An emerging role of the electron–phonon coupling may be responsible for the enhancement of critical temperature in the case of Mo4Ga20Sb.

Superconductivity in the Endohedral Ga Cluster Compound PdGa5

“…4.6 Å; thus, direct Pd–Pd bonding is negligible. Such a situation is also found in other endohedral Ga cluster superconductors, such as Mo 8 Ga 41 , ,,, Mo 6 Ga 31 , , Mo 4 Ga 21 , , and TM 2 Ga 9 families. However in ReGa 5 , the Re–Re distance is clearly within the direct bonding range.…”

“…A number of endohedral Ga superconductors were reported since Xie et al . have suggested the relationship between T c and VEC per TM atom. ,,, Inclusion of these recently reported phases provides further support for that correlation (see Figure a). However, most of the known superconducting Ga endohedral cluster compounds have only up to 22.5 electrons per TM atom, limiting the possibility to extend the conclusions to PdGa 5 with VEC/TM atom = 25.…”

“…Endohedral Ga cluster compounds constitute a family of superconductors that recently gained increased attention. − While crystal structures found in the TM x Ga y (TM, transition metal) compounds are diverse and rather complex, they can be conveniently described as networks of interconnected endohedral Ga clusters. Xie et al .…”

Group-9 Transition Metal Suboxides Adopting the Filled-Ti$_2$Ni Structure: A Class of Superconductors Exhibiting Exceptionally High Upper Critical Fields

“…2,3 Hence, for the search of new and improved superconducting materials one has to rely on utilizing chemical and physical design principles, such as looking for new materials with structural features from known superconductors and electron counting. [4][5][6][7][8][9] One chemical approach to this has been the exploration of materials in which the electronic properties can be tuned precisely by the addition of dopants between layers or into voids positions. [10][11][12][13] For this purpose, electron-donor atoms, or cations, are most commonly incorporated into the structure, as e.g.…”

Synthesis and study the crystal structure of polycrystalline a novel type phase in Zn- Pb- Zr intermetallic alloy by ab initio method via powder XRD system

“…Large volume change in metallic Zn-anodes during charge reaction limits them from practical applications despite the advantages. Intermetallic alloy anodes can successfully lower the volume change upon alkali-ion interaction [6][7][8][9]. Therefore, a variety of binary and ternary Zn-based intermetallic anodes have been explored so far.…”