ABSTRACT
(Bi1-xSbx)2S3solid solution nanowires (0≤x≤0.73) are grown on fluorine-doped tin oxide (FTO) glass via physical vapor transport. The compositions were controlled by varying the Sb2S3source temperature (300 °C-453 °C) by changing the upstream locations of the Sb2S3source in the furnace while keeping the Bi2S3source at the center of the furnace (497 °C). Defect-free nanowires with phase-pure orthorhombic and quasi-1 dimensional crystal structures were grown under a modified vapor-solid mechanism affected by FTO at initial growth stage. The aspect ratios of the nanowires reached the minimum at compositionxâ¼0.6.As the Sb2S3source approached the Bi2S3source,xincreased owing to the increase in the Sb2S3source temperature.x/(1-x), which is proportional to the evaporation flux of the Sb2S3source, could be well-fitted with a thermally activated equation with an apparent activation energy (105kJmol-1). However, at the distance between the Sb2S3and Bi2S3sources, with the Sb2S3source at temperatures higher than 410 °C, the compositions reduced despite the increased Sb2S3evaporation flux. Such retrograde behavior was confirmed by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Raman studies. This retrograde behavior is ascribed to the loss due to the reaction of gaseous Sb species with the Bi2S3source.
