Phase diagram and local environment of Sn and Te: SnTe-Bi and SnTe-Bi2Te3 systems

From thermal analyses and X-ray diffraction the phase diagram of the Bi-SnT e and SnTe-Bi2Te3 sections was determined. The local environment of Sn and Te atoms was studied by Sn-119 and Te-125 Mossbauer spectroscopy. The Bi-Sn Te section showed a eutectic reaction at 267 degrees C and 20 % mole SnTe-8 0 % mole Bi. No intermediate compound was detected. The SnTe-Bi2Te3 section is characterized by a eutectic reaction at 585 degrees C and 40 % mole SnT e-60% mole Bi2Te3 and a peritectic reaction at 600 degrees C and 50 % mole SnTe-50% mole Bi2Te3. It corresponds to the compound SnBi2Te4, which has a rhombohedral layered structure with unit cell parameters a = 4.3954(4) Angs trom and c = 41.606(1) Angstrom. (C) 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.