Preparation and superconductivity of intercalation compounds of TiNCl with aliphatic amines

A FeSe-based superconductor (C2H8N2)xFeSe with only ethylenediamine intercalated

“…The structural transition from a tetragonal to an orthorhombic phase accompanied the intercalation of EDA, suggesting that the molecule planes were inclined or parallel to FeSe layers. The similar behavior was observed in the system of the EDA intercalated TiNCl [22]. It is noted that the structural phase transition from tetragonal to orthorhombic in EDA intercalated FeSe sample is different from the case of FeSe [24,25] on cooling which finally forms a √ -2 ×√ -2 supercell.…”

“…It is noted that the structural phase transition from tetragonal to orthorhombic in EDA intercalated FeSe sample is different from the case of FeSe [24,25] on cooling which finally forms a √ -2 ×√ -2 supercell. The steric size of EDA is estimated to be~6.4 Å in length and~3.6 Å in thickness [22]. The increase in the interlayer spacing is 5.3133 Å, compared to the starting material Fe 1.01 Se, which is not large enough to accommodate molecules of EDA perpendicular to the FeSe layers, and if the EDA molecules lie in parallel with the FeSe layers, monolayer is too thin while double layer is too thick.…”

“…Aliphatic amines including diamine have been widely used for the intercalation to layered dichalcogenides (e.g., TiS 2 , TaS 2 , NbS 2 [19], SnS 2 [20,21]) and metal nitride halides (e.g., TiNCl [22]) via the solvothermal method, which prompted us to visualize the similar intercalation compounds of FeSe. Herein, we report a new superconductor (C 2 H 8 N 2 ) x FeSe with ethylenediamine (EDA) solely intercalated into FeSe synthesized by the solvothermal method.…”

Unconventional superconductivity in electron-doped layered metal nitride halides MNX (M= Ti, Zr, Hf; X= Cl, Br, I)

“…Recently the α-structured layered TiNCl has been electrondoped by the intercalation of alkali metals as well as organic Lewis bases, which turned out to become superconductors with relatively high T c 's [9,10,76]. As mentioned in the above section, the structures of the two kinds of MNX (α-and β-forms) are very different within the layers, and accordingly they have different types of band structures.…”

“…However, all of the compounds with n-alkyl monoamines were found to be not superconductors down to 2 K [76]. It is interesting that ethylene diamine (NH 2 CH 2 CH 2 NH 2 ) can form a similar intercalation compound with TiNCl with a basal spacing of 11.12 Å, which surprisingly shows superconductivity with T c = 10.5 K [76]. Systematic studies have been done using alkylene diamines with different numbers of carbon atoms, NH 2 C n H 2n NH 2 (2 ≦ n ≦ 12) [76].…”