Anti-Th3P4 structure

Hulliger and Ott (1977) reported the anti-Th3P4 structure type for Eu4TeSb2, a = 0.9814 from X-ray powder diffraction. The sample was placed in tantalum or molybdenum crucible and heated in quartz tube below 1273 K. 

U3X4 (X = P, As, Sb, Bi, Se, Te), Sr4Bi3, Ba4Bi3, Ba4As 2.6 are isostructural and crystallize as anti-Th3P4-type structure. 

Fig. 33,5. The anti-Th3P4 or Gd Bis structure. Large spheres Bi, small spheres Gd. The coordination polyhedra [GdBij] and [BiGde] are emphasized on the right part. On the left the additional Gd-3Gd contacts are indicated by dotted lines for each of the two distinguishable Gd sublattices.

These compounds were prepared with divalent rare earths (R = Sm, Eu, Yb) by reaction of elements or binaries (Hulliger, 1979b). They adopt the anti-Th3P4-type structure (Pearson symbol c/28, space group I4M (No. 220), Z = 4) and are assumed to be semiconducting. Eu4Bi2Te orders antiferromagnetically at Tn = 36 K. 

Structure type anti-Th3P4 (Meisel 1939 fig. 7, table 5) has space group 143d, o=0.9026 (for EU3P2) (Hulliger and Vogt 1970). 

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