ZrBeSi structure type

The structure types Caln2, ZrBeSi, NdPtSb, LiGaGe, CaLiSn,... 

If the T3Pb3 layers are planar, e.g. YbHgPb (Merlo et al., 1993), the ZrBeSi type (Nielsen and Baenziger, 1954) occurs. This structure type mostly occurs when the rare earth atoms have a large radius. The stacking sequence of the T3Pb3 hexagons is similar in the three structure types, i.e. AB AB. 

Number 1 corresponds to AIB2 structure type 2 - ZrBeSi 3 - MgAgAs 4 - Caln2 5 - TiNiSi 6 - LiGaGe 7-KHg2 8-CeScSi. 

Structure type ZrBeSi (Nielsen and Baenziger 1954 table 54) has space group Pfis/mmc, a = 0.4248, c = 0.1199 (for CePdP) (Johrendt and Mewis 1990). 

Early investigations of the PrNiSb compound showed that it had the AlB2-type structure with a = 0.4376, c = 0.4053 (Pecharsky et al., 1983a X-ray powder analysis). For experimental procedure, see ScNiSb. At variance with these data, Hartjes and Jeitschko (1995) suggested a ZrBeSi type structure, a = 0.4375, c = 0.8123 from X-ray powder diffraction. For experimental details, see LaNiSb. 

Eu-Cu-Sb. EuCuSb was found to crystallize with the ZrBeSi type structure with lattice parameters of a = 0.4512, c = 0.8542 (Tomuschat and Schuster, 1981 X-ray photographic powder method). 

The only information on the interaction of europium with zinc and germanium is due to the work of Pottgen (1996) who reported the crystal structure of EuZnGe (ZrBeSi type, a = 0.4372, c = 0.8604 X-ray powder diffraction). 

Fig. 3. Trigonal-prism stacking variants (a) ZrBeSi = ordered AIB type (b) hypothetical M3X4 structure (c)3 -MoN (d)fi -WN (e) rhombohedral 8-WN and (f) WC structure.

Fig. 15. Structures of (a) low- (LiGaGe-type) and (b) high-temperature YbCuBi (ZrBeSi-type).

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