MgAgAs

As Mg Ag MgAgAs (Zintl phase) F43m LiMgAs, NiZnSb, BAlBe, SiCN... 

There are four molecules in the unit cell, T%, F 43 m. Compounds with the MgAgAs structure are given in Table 6.5. 

Figure 6.13. The zinc blende (ZnS) structure is shown with the Mg atoms in the other T layer. They are combined to give a fluorite-like structure for MgAgAs.

Table 6.5. Compounds with the MgAgAs (3 3PTT) structure.

ScUi-Sb. Early investigations of the ScNiSb compound showed that it had the MgAgAs-type with a = 0.6062 (Dwight, 1974) from an X-ray powder analysis of an alloy... 

Sc-Pt-Sb. ScPtSb belongs to the MgAgAs-type, a = 0.6312 (Dwight, 1974) (X-ray powder analysis). Sample preparation, see ScNiSb. 

Sm-PtSb. SmPtSb crystallizes with the MgAgAs-type structure, a = 0.6554 (Rossi et al 1981 powder X-ray diffraction data). For the experimental details, see the LaPtSb system. 

An early investigation of the TbNiSb compound showed that it had the MgAgAs-type with a = 0.6327 (Dwight, 1974), from an X-ray powder analysis of an alloy arc melted under argon and annealed at 973 K. Pecharsky et al. (1983a) and Hartjes and Jeitschko (1995) confirmed the crystal structure and obtained the lattice parameters as a = 0.6302 and a = 0.6304, respectively, by X-ray powder diffraction. For experimental details, see ScNiSb and LaNiSb respectively. 

TbJ t-Sb. An investigation of the TbPtSb compound by X-ray powder diffraction showed that it had the MgAgAs type structure with a = 0.6540 (Dwight, 1974). For the sample preparation, see ScNiSb. 

Preliminary results on low temperature transport properties in YbPdSb system with MgAgAs type structure are presented by Aliev et al. (1988). Resistivity shows a maximum at T = 50-100 K and the Fermi-liquid decrease of q go + AT2 at helium temperatures. The high value of the A coefficient 5 p 2 cm/K2 indicates the possibility of the heavy fermion behavior with y about 300MOO mJ/molK2. The Seebeck coefficient S is positive and shows a maximum Smax 22 pV/K at T 200 K. 

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