New ternary niobium tellurides AxNb6Te8 (A = Ca, Sr, Ba, La, and Nd; x = 0.22-0.32) have been prepared by molten salt ion exchange reactions of TlxNb6Te8 with rare earth/alkaline earth iodides AI3/AI2 at relatively low temperatures, 535-795°C. Most of the niobium tellurides show metallic behavior followed by superconductivity at low temperatures, 4-6 K. Polycrystalline La0.32Nb6Te8 and Nd0.24Nb6Te8 show a resistivity anomaly at 46 and 43 K, respectively, while polycrystalline Tl0.91Nb6Te8 shows a broad resistivity anomaly at 160-220 K. The resistivity anomaly observed in Tl0.91Nb6Te8 appears to be accompanied by a minor structural distortion evidenced in differential scanning calorimetry. The resistivity anomalies observed in La0.32Nb6Te8 and Nd0.24Nb6Te8 are similar to those observed at ∼40 K for Nb3Te4 and may be related to the onset of a charge density wave type instability.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Ceramics and Composites
- Materials Chemistry
- Inorganic Chemistry
- Physical and Theoretical Chemistry