Synthesis and Crystal Structure of a New Layered Carbide ZrAl₄C₄

Abstract

A new ternary layered carbide, ZrAl 4 C 4 , has been synthesized and characterized by X-ray powder diffraction. The crystal structure was successfully determined using direct methods and further refined by the Rietveld method. The crystal is trigonal (space group P3m1, Z 5 2) with lattice dimensions a 5 0.332471(3) nm, c 5 2.19717(2) nm, and V 5 0.210330(3) nm 3 . The final reliability indices calculated from the Rietveld refinement were R wp 5 6.56% (S 5 1.58), R p 5 4.92%, R B 5 1.90%, and R F 5 0.98%. The compound shows an intergrowth structure with NaCl-type [Zr 2 C 3 ] thin slabs separated by Al 4 C 3 -type [Al 8 C 7 ] layers.Ã All distances shorter than 0.33 nm (metal-metal) and 0.25 nm (metal-carbon) are given.

[Zr0.72Y0.28]Al4C4: A new member of the homologous series (MC)l(T4C3)m (M=Zr, Y and Hf, T=Al, Si and Ge)

“…The C-C distances of the networks, ranging from 0.3318 to 0.3328 nm, are comparable to those of ZrC and Al 4 C 3 crystals; the former distance is 0.3319 nm ( ¼ a(ZrC)/O2) [4] and that of the latter is 0.3335 nm ( ¼ a(Al 4 C 3 )) [5], where a(ZrC) and a(Al 4 C 3 ) represent the a-axis lengths. Fukuda et al have therefore proposed that the closeness of the C-C distances between ZrC and Al 4 C 3 crystals, being expressed by the equation a(ZrC)/ O2Ea(Al 4 C 3 ), is the principal reason for the formation of these layered carbides [1][2][3]6]. However, attempts to synthesize the new members of the homologous series such as ''(ZrC)Al 4 C 3 (l ¼ 1, m ¼ 1)'' and ''(ZrC) 3 (Al 4 C 3 ) 2 (l ¼ 3, m ¼ 2)'' were unsuccessful.…”

“…Fukuda et al have therefore proposed that the closeness of the C-C distances between ZrC and Al 4 C 3 crystals, being expressed by the equation a(ZrC)/ O2Ea(Al 4 C 3 ), is the principal reason for the formation of these layered carbides [1][2][3]6]. However, attempts to synthesize the new members of the homologous series such as ''(ZrC)Al 4 C 3 (l ¼ 1, m ¼ 1)'' and ''(ZrC) 3 (Al 4 C 3 ) 2 (l ¼ 3, m ¼ 2)'' were unsuccessful. For the NaCl-type compound ZrC, the unit cell content is [Zr 4 C 4 ], indicating that the existence of the homologous phases with lX4 is thermodynamically improbable [6].…”

“…Recent efforts in our laboratory have aimed at defining a new homologous series of phases (ZrC) l (Al 4 C 3 ) m (l, m ¼ integers) [1][2][3]. Members of this series that have been confirmed so far include (ZrC) 2 Al 4 C 3 (l ¼ 2, m ¼ 1), (ZrC) 3 Al 4 C 3 (l ¼ 3, m ¼ 1), (ZrC)(Al 4 C 3 ) 2 (l ¼ 1, m ¼ 2) and (ZrC) 2 (Al 4 C 3 ) 2 (l ¼ 2, m ¼ 2).…”

Thin Film Synthesis of New Nanolaminated Ternary Carbides

“…The incident (primary) ions are commonly 35 Cl, 79 Br, 127 I, 63 Cu and 197 Au with an incident energy from few tens up to few hundreds MeV. ERDA is capable of detecting and quantifying all elements lighter than incident ion species, and is also possible to detect heavier elements with special detectors.…”

Phase Formation of Nanolaminated Transition Metal Carbide Thin Films

“…Moreover, the MAl3C3 phase has only been experimentally discovered when M is a group 3 or f-block transition metal (e.g. ScAl3C3 [169], YAl3C3 [167], UAl3C3 and YbAl3C3 [170]), while the MAl4C4 phase (M = Zr and Hf) was identified in a different space group 3 1 (156) than the other members [171,172]. Interestingly, the tendency of forming nanolaminated phases with Al3C2 or Al4C3 blocks is restricted to group 3 -4 transition metals, except Ti, which compete with the formation of conventional MAX phases, e.g.…”