Two novel N$\wedge $O-type Schiff base ligands and the corresponding Co(II) complexes are reported. Thermogravimetric analysis indicated that the complexes are potential molecular precursors for the fabrication of cobalt and cobalt-containing nanomaterials. The significant difference in the thermal decomposition profiles is recognized as an influence of structural differences on the complexes. Thus, the complexes were thermally decomposed using the melt and hot injection methods to examine the properties of the obtained cobalt and cobalt sulfide nanoparticles, respectively. The reaction parameters employed during the fabrication processes, in addition to structural differences, influenced the morphological and crystallographic phases and magnetic properties of the synthesized nanoparticles. We have investigated the morphological properties and the crystallographic phase compositions of the nanoparticles by various electron microscopy and diffraction techniques, as well as energy-dispersive X-ray spectroscopy. The melt reactions produced phase-pure cobalt nanoparticles, which exhibit ferromagnetic behavior. The hot injection method utilized 1-dodecanethiol (DDT) as both sulfur source and capping agent. We indexed the DDT-capped cobalt sulfide nanoparticles to cubic Co$_9}$S$_8}$ and Co$_3}$S$_4}$ phases using powder X-ray diffraction, high-resolution transmission electron microscopy imaging, and selected area electron diffraction. The crystallite sizes for Co$_9}$S$_8}$ and Co$_3}$S$_4}$ nanoparticles, based on the Scherrer equation, were 12.4 nm and 14.1 nm, respectively. We find significant differences in the magnetic properties, attributed to nonmagnetic inclusions and vacancies due to the presence of S atoms.
报道了两种新型的N$\wedge $O型Schiff碱
配体及其对应的Co(II)复合物。热重分析表明,这些复合物是制造
钴及
钴基纳米材料的潜在分子前驱体。热分解特征的显著差异被认为是复合物结构差异的影响。因此,采用熔融法和热注射法对复合物进行热分解,以分别考察获得的
钴和
钴硫化物纳米颗粒的性质。在制造过程中使用的反应参数,以及结构差异,影响了合成纳米颗粒的形态特征、晶体相和磁性。我们通过多种电子显微镜和衍射技术及能量色散X射线光谱法研究了纳米颗粒的形态特征和晶体相组成。熔融反应生成的
钴纳米颗粒具有相纯性,并展示了
铁磁行为。热注射法则使用1-
十二烷硫醇(DDT)作为
硫源和包覆剂。我们利用粉末X射线衍射、高分辨率透射电子显微镜成像和选区电子衍射,对DDT包覆的
钴硫化物纳米颗粒进行了立方相Co$_9}$S$_8}$和Co$_3}$S$_4}$的索引。根据Scherrer方程,Co$_9}$S$_8}$和Co$_3}$S$_4}$纳米颗粒的晶粒尺寸分别为12.4 nm和14.1 nm。我们发现磁性特性存在显著差异,归因于由于S原子的存在而产生的非磁性夹杂物和空位。