Growth of NaFe4P12 Skutterudite Single Crystalline Nanosprings Synthesized through a Hydrothermal−Reduction−Alloying Method

Abstract

NaFe4P12 nanosprings were synthesized using a hydrothermal method at 170 °C for 24 h. The nanosprings are 1000−5000 nm in length and 200−1000 nm in diameter and consist of coiled nanobelts of 80−150 nm in width and 20−50 nm in thickness. With an increase in the annealing time, the nanospring grows as a macrorod with a multilayered helical tubular structure. X-ray diffraction (XRD) patterns indicate that the nanosprings have the skutterudite crystal structure with cell parameter a = 7.782 Å. Electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM) prove that the nanobelts grow along the (111) plane and that their growth direction is not parallel to the [110] direction in the growth plane. A possible growth process for NaFe4P12 nanosprings is suggested.