Lanthanide(III) Nitride Bismuthides M₂NBi (M = La–Nd) and Their Potential as Topological Insulators

Abstract

Four lanthanide(III) nitride bismuthides of the new class M 2 NBi (M = La-Nd) have been synthesized by the reaction of the respective lanthanide metal (M) with caesium azide (CsN 3 ), elemental bismuth (Bi), the corresponding lanthanide trichloride (MCl 3 ), and caesium chloride (CsCl) as flux in evacuated silica tubes for 7 days at 900°C. The M 2 NBi compounds crystallize tetragonally in the space group P4/nmm with Z = 2 with the lattice parameters a = 480.61(4) pm, c = 948.34(9) pm (M = La), a = 475.48(4) pm, c = 938.76(9) pm (M = Ce), a = 471.80(4) pm, c = 929.51(9) pm (M = Pr), and a = 468.13(4), c = 921.08(9) pm (M = Nd). As the main structural feature of the crystal structures, ϱ 2 {[NM 2 ] 3+ } layers of condensed nitride-centered square pyramids of M 3+ cations dominate. These pyramids, in which the base is built of [a]

About Lanthanoid Fluoride Selenide Oxoselenotantalates with the Composition Ln3F2Se2TaO4 (Ln = La – Nd)

“…[16] For the oxide-poor tetragonal oxide selenides Ln 10 OSe 14 only the compounds with Ln = La -Nd seem to exist [28][29][30] and only the lanthanoids Ln = La -Nd form the nitride tellurides Ln 13 N 5 Te 12 [31] or the nitride bismuthides Ln 2 NBi. [32] With oxoselenate(IV) anions the Ln 2 O[SeO 3 ] 2 series starts with the samarium compound as the first one of the lanthanoids [33,34] [35] has a unique structure and the rest of the LnCl[SeO 3 ] [35][36][37][38] series starts with Ln = Sm again. So the possibility of building a crystal structure is depending among other things much on the size of the respective Ln 3+ cation.…”

Renaissance of the Stella Quadrangula: The Lanthanoid Nitride Tellurides Ln13N5Te12 (Ln = La–Nd)

“…Ln 2 N X 3 and Ln 3 N X 6 with Ln = La–Nd, Gd; X = Cl, Br), but recent developments revealed further composition possibilities with pnictogenides as third anionic structure‐filler. In the case of nitride bismuthides Ln 2 NBi ( Ln = La–Nd), which crystallize in the anti‐BaNiS 2 ‐type structure with layers 2 ∞ {[N Ln 2 ] 3+ } of condensed nitride‐centered ( Ln 3+ ) 5 square pyramids, could be realized as the first representatives of lanthanoid nitride pnictogenides so far. However, a closer look at the ternary lanthanoid nitride chalcogenides illustrates many different structures, being realized especially for the nitride‐rich examples Ln 4 N 2 Ch 3 ( Ln = La–Nd, Sm, Gd–Dy; Ch = S–Te).…”