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Planar B 4 Rhomboids: The Rare Earth Boride Halides RE 4 X 5 B 4

1997; American Chemical Society; Volume: 101; Issue: 48 Linguagem: Inglês

10.1021/jp971500q

1520-6106

Hj. Mattausch, Arndt Simon, Claudia Felser,

Boron and Carbon Nanomaterials Research

The new compounds RE4X5B4 (RE = La, Ce, Pr, Gd and X = Br, I) and RE4I5B2C (RE = La, Ce) are prepared via the reaction of RE metal, REX3 and B, or B and C at temperatures 1670 ≥ T ≥ 1270 K in welded tantalum ampoules. Chains of interconnected B4 rhomboids are the characteristic features of the crystal structures. According to band structure calculations, the compounds are one-dimensional metals which undergo a gradual metal-to-semiconductor transition at low temperature as experimentally indicated by the steep inrease of electrical resistivity.