ChemInform Abstract: The Crystal Structural Features of τ Borides as Derived from the Prototype Co21Ta2B6.

Abstract

The structure of Co21‐xTa2+xB6 (x = 0.18) is refined on the basis of single crystal XRD data and described in detail.

Phase transitions in some nickel-rich nickel–boron–titanium hard alloys

“…3b) performed on these alloys, the chemical formula Ni 21 Ti 3 B 6 is proposed for this ternary cubic phase in this work. This result is in good agreement with that of Finch et al [22,23] and Stadelmaier et al [24]. For the quenched alloy E, the primary phase TiB 2 is surrounded by the eutectic structure TiB 2 -as shown in Fig.…”

Stability, Crystal Chemistry, and Magnetism of U2+xNi21–xB6 and Nb3–yNi20+yB6 and the Role of Uranium in the Formation of the Quaternary U2–zNbzNi21B6 and UδNb3−δNi20B6 Systems

“…Similar results have been found for all phases reported to crystallize in either the W 2 Cr 21 C 6 - or Mg 3 Ni 20 B 6 -type for which the structure had been refined from single-crystal XRD data. − An analysis of such data shows that the M 2 T 21 B 6 compounds adopting the W 2 Cr 21 C 6 -type [formed between a IIIA or IVA group element (M = Ga, In, Sn), a transition element (M = Ta, Zr), or a rare-earth element (M = Sc, Er, Yb, Lu) with Co and Ni] are those where the 4 a site is always occupied by the transition element Co­(Ni), while the M 3 T 20 B 6 compounds crystallizing in the Mg 3 Ni 20 B 6 -type [formed between a IIIA and IVA group element (M = Al, Ga, In, Sn) and Co or Ni] are those where the 4 a and 8 c sites always show mixed M/Co­(Ni) occupancy. For all of these phases, the 48 h and 32 f sites always remain fully occupied by Co (Ni) atoms and the 24 e site by B atoms.…”

“…For several of the M 2 T 21 X 6 and M 3 T 20 X 6 compounds, the crystal structure has been refined from single-crystal XRD data. By looking at the previous reports for the W 2 Cr 21 C 6 -type compounds (Ga 1.1 Co 21.9 B 6 , Sn 1.6 Co 21.4 B 6 , Ta 2 Co 21 B 6 , Er 1.82 Ni 21 B 6 , Yb 1.70 Ni 21 B 6 , Yb 1.86 Ni 21 B 6 , Lu 1.65 Ni 21 B 6 , In 2 Ni 21 B 6 , Sc 2 Ni 21 B 6 , Zr 2 Ni 21 B 6 , In 2 Ni 21 P 6 , and Sn 2 Ni 21 P 6 ) and the Mg 3 Ni 20 B 6 -type compounds (Al 2.1 Co 20.9 B 6 , Al 3 Ni 20 B 6 , Al 2.49 Ni 20.51 B 6 , Zn 1.6 Ni 21.4 B 6 , Ga 3 Ni 20 B 6 , In 0.8 Ni 22.2 B 6 , InNi 22 B 6 , In 1.4 Ni 21.6 B 6 , Sn 1.9 Ni 21.1 B 6 , Ce 3 Pd 20 Ge 6 , Mg 3 Ni 20 P 6 , Mn 3 Ni 20 P 6 , and Ir 9.20 Fe 13.8 B 6 ), it becomes evident that for most of them only the nominal composition is reported (thus appearing as stoichiometric line compounds) . Moreover, because of the lack of structural refinement, it remains unclear if a given compound adopts the M 2 T 21 X 6 - or M 3 T 20 X 6 -type structure.…”