A new quaternary layered carbide, (ZrC)3[Al3.56Si0.44]C3, has been synthesized and characterized by x-ray powder diffraction and thermopower and electrical conductivity measurements. The crystal structure was successfully determined using direct methods and further refined by the Rietveld method. The crystal is trigonal (space group R3m*, Z = 3) with lattice dimensions a = 0.331389(7), c = 4.90084(7) nm, and V = 0.46610(1) nm3. The final reliability indices calculated from the Rietveld refinement were Rwp = 9.53% (S = 1.70), Rp = 7.22%, RB = 1.81%, and RF = 0.94%. The crystal structure is composed of the NaCl-type [Zr3C4] slabs separated by the Al4C3-type [Al0.89Si0.11C] layers. This material had thermoelectric properties comparable to the layered carbides (ZrC)2[Al3.56Si0.44]C3 (Zr2[Al3.56Si0.44]C5), (ZrC)2Al3C2, and (ZrC)3Al3C2 in the temperature range of 373–1273 K, with the maximal power-factor value of 6.6 × 10−5 W m−1K−2 at 545 K. The two quaternary carbides have been found to form a homologous series with the general formula of (ZrC)n[Al3.56Si0.44]C3 (n = 2 and 3).
The crystal structure of YAl3C3 was refined from laboratory X‐ray powder diffraction data (CuKα1) using the Rietveld method. The crystal structure is hexagonal (space group P63mc, Z=2) with lattice dimensions a=0.342157(4) nm, c=1.72820(1) nm, and V=0.175217(3) nm3. The final reliability indices were Rwp=9.94% (Rwp/Re=1.18), Rp=7.36%, RB=1.77%, and RF=1.03%. The compound shows an intergrowth structure with electroconductive [YC2] thin slabs separated by Al4C3‐type [AlC] layers. This material had thermoelectric properties superior to those of the layered carbides Zr2[Al3.56Si0.44]C5, Zr2Al3C4, and Zr3Al3C5 in the temperature range of 500– 1073 K, with a maximal power‐factor value of 1.96 × 10−4 W·(m·K2)−1 at 1073 K.
A new layered carbide, [Zr1.97Y0.03]Al4C5, has been synthesized and characterized by X‐ray powder diffraction (XRPD), transmission electron microscopy, and energy‐dispersive X‐ray spectroscopy (EDX). The atom ratios [Zr:Y] were determined by EDX, and the crystal structure was refined from laboratory XRPD data (CuKα1) using the Rietveld method. The crystal is trigonal (space group R3m, Z=3) with lattice dimensions of a=0.331934(4) nm, c=4.09459(3) nm, and V=0.390701(7) nm3. The final reliability indices were Rwp=10.29% (S=1.31), Rp=7.45%, RB=1.63%, and RF=1.04%. The compound shows an intergrowth structure with NaCl‐type [Zr1.97Y0.03C3] thin slabs separated by Al4C3‐type [AlC] layers. This material is isostructural with Zr2[Al3.56Si0.44]C5.
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