Lu₈Te and Lu₇Te. Novel Substitutional Derivatives of Lutetium Metal

Abstract

Monocrystals of Lu8Te are synthesized by disproportionation of Lu7Te at 1000-1200 degrees C or by direct reaction of Lu plus Lu2Te3 at 1000 degrees C for 2 weeks. Lu7Te is produced by arc-melting of a suitable Lu-Lu2Te3 mixture, with good crystals being formed by subsequent annealing at 1300 degrees C. The structures of Lu8Te (P2m, Z = 1) and Lu7Te (Cmcm, Z = 4) exhibit simple AB... packing of distorted, not close-packed, layers along one short axis (, , respectively). Puckered Lu, Te layers are stacked normal to (010) or (001) in six- or eight-layer repeat sequences, with Te substituting for every third or every other Lu in every third or fourth layer, respectively. Strong Lu-Te bonding is indicated. Both Te substitutions decrease the volume per atom from that in hcp. Lu and also decrease the coordination number of all atoms from 12 to 9-11.

Lu2@C2n (2n = 82, 84, 86): Crystallographic Evidence of Direct Lu–Lu Bonding between Two Divalent Lutetium Ions Inside Fullerene Cages

“…Figures 3a−d S4). These values are all comparable to a Lu−Lu single bond length (3.28−3.81 Å), 37,38 confirming crystallographically the direct Lu−Lu bonding to result in a divalent state for each lutetium ion in these cages. Theoretical calculations were conducted to rationalize the formation of the Lu−Lu bond in these compounds.…”

Exploratory synthesis of reduced rare-earth-metal halides, chalcogenides, intermetallics

“…20illustrates these structures in projections down the short ∼3.7Å axes, (a) hexagonal Lu 8 Te and (b) orthorhombic Lu 7 Te[107]. Both exhibit simple hexagonal close-packed (AB.…”

A Bismuth‐Stabilized Metal‐Rich Telluride Lu9Bi≈1.0Te≈1.0 – Synthesis and Characterization

“…All attempts to synthesize the hypothetical limiting Lu 9 Te 2 and Lu 9 Bi 2 failed. Arc-melting the composition Lu 9 Te 2 yielded mainly Lu 7 Te [15] (along with some unidentified product), and these produced a mixture of Lu 8 Te [15] and LuTe on annealing at 1100°C. A Lu 9 Bi 2 reaction at 1300°C incorporated some Mo from the foil used to protect the pellet from the Ta and yielded Lu 6 MoBi 2 , a new congener of Lu 6 MoSb 2 [21] [Zr 6 CoAs 2 -type, P62m, a = 8.030(1) Å, c = 4.3052(9) Å] as identified from single crystal analysis.…”

“…Similar characteristics have been seen in recent studies of rare-earth-metal tellurides in other structures as well [7,8] and may be inferred from earlier extended Hückel results as well. [15,21] The considerable numbers of independent distances between Lu atoms in this large and relatively low symmetry structure are difficult to sort out in detail. Extensive delocalization in the bonding is evident from the band results, so that reasons for all of the two-atom separations become quite opaque beyond some minimal matrix (size or packing) effects.…”

“…Intriguingly, only a few R-metals have been as productive as Sc and Y, the heavier Er and Lu, and a few examples with Gd, Dy and Ho. [9,14] Lutetium appears to be exceptional in this regard, including a few remarkable binaries such as Lu 7 Te, Lu 8 Te [15] with simple and elegant hexagonal packing of distorted Lu and Te layers, and Lu 11 Te 4 [16] with two independent condensed puckered Lu sheets separated by individual Te atoms, the metal sublattices being distinctively different from that in Sc 8 We here report on our investigations in metal-rich phase space of the Lu-Bi-Te system, motivated by a general interest in the analogous pnictogen (Sb, Bi) systems. Particularly noteworthy are the absences of any Bi or Sb analogs of the binary R-rich tellurides; rather, the heavier R elements GdLu only form one of the common structure types with 5:3 stoichiometries.…”